diff --git a/subprojects/libcr51sign/src/libcr51sign.c b/subprojects/libcr51sign/src/libcr51sign.c
index fff1826..75d8b70 100644
--- a/subprojects/libcr51sign/src/libcr51sign.c
+++ b/subprojects/libcr51sign/src/libcr51sign.c
@@ -53,943 +53,923 @@
 #define BUILD_ASSERT(cond) ((void)sizeof(char[1 - 2 * !(cond)]))
 #endif
 
-    typedef enum libcr51sign_validation_failure_reason failure_reason;
+typedef enum libcr51sign_validation_failure_reason failure_reason;
 
-    // Returns the bytes size of keys used in the given signature_scheme.
-    // Return error if signature_scheme is invalid.
-    //
-    static failure_reason get_key_size(enum signature_scheme signature_scheme,
-                                       uint16_t* key_size)
+// Returns the bytes size of keys used in the given signature_scheme.
+// Return error if signature_scheme is invalid.
+//
+static failure_reason get_key_size(enum signature_scheme signature_scheme,
+                                   uint16_t* key_size)
+{
+    switch (signature_scheme)
     {
-        switch (signature_scheme)
-        {
-            case SIGNATURE_RSA2048_PKCS15:
-                *key_size = 256;
-                return LIBCR51SIGN_SUCCESS;
-            case SIGNATURE_RSA3072_PKCS15:
-                *key_size = 384;
-                return LIBCR51SIGN_SUCCESS;
-            case SIGNATURE_RSA4096_PKCS15:
-            case SIGNATURE_RSA4096_PKCS15_SHA512:
-                *key_size = 512;
-                return LIBCR51SIGN_SUCCESS;
-            default:
-                return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
-        }
+        case SIGNATURE_RSA2048_PKCS15:
+            *key_size = 256;
+            return LIBCR51SIGN_SUCCESS;
+        case SIGNATURE_RSA3072_PKCS15:
+            *key_size = 384;
+            return LIBCR51SIGN_SUCCESS;
+        case SIGNATURE_RSA4096_PKCS15:
+        case SIGNATURE_RSA4096_PKCS15_SHA512:
+            *key_size = 512;
+            return LIBCR51SIGN_SUCCESS;
+        default:
+            return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
+    }
+}
+
+// Returns the hash_type for a given signature scheme
+// Returns error if scheme is invalid.
+failure_reason get_hash_type_from_signature(enum signature_scheme scheme,
+                                            enum hash_type* type)
+{
+    switch (scheme)
+    {
+        case SIGNATURE_RSA2048_PKCS15:
+        case SIGNATURE_RSA3072_PKCS15:
+        case SIGNATURE_RSA4096_PKCS15:
+            *type = HASH_SHA2_256;
+            return LIBCR51SIGN_SUCCESS;
+        case SIGNATURE_RSA4096_PKCS15_SHA512:
+            *type = HASH_SHA2_512;
+            return LIBCR51SIGN_SUCCESS;
+        default:
+            return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
+    }
+}
+
+// Check if the given hash_type is supported.
+// Returns error if hash_type is not supported.
+static failure_reason is_hash_type_supported(enum hash_type type)
+{
+    switch (type)
+    {
+        case HASH_SHA2_256:
+        case HASH_SHA2_512:
+            return LIBCR51SIGN_SUCCESS;
+        default:
+            return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE;
+    }
+}
+
+// Determines digest size for a given hash_type.
+// Returns error if hash_type is not supported.
+static failure_reason get_hash_digest_size(enum hash_type type, uint32_t* size)
+{
+    switch (type)
+    {
+        case HASH_SHA2_256:
+            *size = LIBCR51SIGN_SHA256_DIGEST_SIZE;
+            return LIBCR51SIGN_SUCCESS;
+        case HASH_SHA2_512:
+            *size = LIBCR51SIGN_SHA512_DIGEST_SIZE;
+            return LIBCR51SIGN_SUCCESS;
+        default:
+            return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE;
+    }
+}
+
+// Determines hash struct size for a given hash_type.
+// Returns error if hash_type is not supported.
+static failure_reason get_hash_struct_size(enum hash_type type, uint32_t* size)
+{
+    switch (type)
+    {
+        case HASH_SHA2_256:
+            *size = sizeof(struct hash_sha256);
+            return LIBCR51SIGN_SUCCESS;
+        case HASH_SHA2_512:
+            *size = sizeof(struct hash_sha256);
+            return LIBCR51SIGN_SUCCESS;
+        default:
+            return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE;
+    }
+}
+
+// Checks that:
+//  - The signing key is trusted
+//  - The target version is not denylisted
+// If validating a staged update, also checks that:
+//  - The target image family matches the current image family
+//  - The image type transition is legal (i.e. dev -> *|| prod -> prod) or
+//    alternatively that the hardware ID is allowlisted
+// Assuming the caller has performed following:
+// board_get_base_key_index();
+// board_get_key_array
+// Possible return codes:
+// LIBCR51SIGN_SUCCESS = 0,
+// LIBCR51SIGN_ERROR_RUNTIME_FAILURE = 1,
+// LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR = 3,
+// LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY = 4,
+// LIBCR51SIGN_ERROR_IMAGE_TYPE_DISALLOWED = 5,
+
+static failure_reason validate_transition(const struct libcr51sign_ctx* ctx,
+                                          const struct libcr51sign_intf* intf,
+                                          uint32_t signature_struct_offset)
+{
+    BUILD_ASSERT((offsetof(struct signature_rsa2048_pkcs15, modulus) ==
+                      SIGNATURE_OFFSET &&
+                  offsetof(struct signature_rsa3072_pkcs15, modulus) ==
+                      SIGNATURE_OFFSET &&
+                  offsetof(struct signature_rsa4096_pkcs15, modulus) ==
+                      SIGNATURE_OFFSET));
+
+    // Read up to the modulus.
+    enum
+    {
+        read_len = SIGNATURE_OFFSET
+    };
+    uint8_t buffer[read_len];
+    int rv;
+    rv = intf->read(ctx, signature_struct_offset, read_len, buffer);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_transition: failed to read signature struct\n");
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+    }
+    if (*(uint32_t*)buffer != SIGNATURE_MAGIC)
+    {
+        CPRINTS(ctx, "validate_transition: bad signature magic\n");
+        return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
     }
 
-    // Returns the hash_type for a given signature scheme
-    // Returns error if scheme is invalid.
-    failure_reason get_hash_type_from_signature(enum signature_scheme scheme,
-                                                enum hash_type* type)
+    if (ctx->descriptor.image_family != ctx->current_image_family &&
+        ctx->descriptor.image_family != IMAGE_FAMILY_ALL &&
+        ctx->current_image_family != IMAGE_FAMILY_ALL)
     {
-        switch (scheme)
-        {
-            case SIGNATURE_RSA2048_PKCS15:
-            case SIGNATURE_RSA3072_PKCS15:
-            case SIGNATURE_RSA4096_PKCS15:
-                *type = HASH_SHA2_256;
-                return LIBCR51SIGN_SUCCESS;
-            case SIGNATURE_RSA4096_PKCS15_SHA512:
-                *type = HASH_SHA2_512;
-                return LIBCR51SIGN_SUCCESS;
-            default:
-                return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
-        }
+        CPRINTS(ctx, "validate_transition: invalid image family\n");
+        return LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY;
     }
 
-    // Check if the given hash_type is supported.
-    // Returns error if hash_type is not supported.
-    static failure_reason is_hash_type_supported(enum hash_type type)
+    if (intf->is_production_mode == NULL)
     {
-        switch (type)
+        CPRINTS(ctx, "validate_transition: missing is_production_mode\n");
+        return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
+    }
+    if (intf->is_production_mode() && (ctx->descriptor.image_type == IMAGE_DEV))
+    {
+        CPRINTS(ctx, "validate_transition: checking exemption allowlist\n");
+
+        // If function is NULL or if the function call return false, return
+        // error
+        if (intf->prod_to_dev_downgrade_allowed == NULL ||
+            !intf->prod_to_dev_downgrade_allowed())
         {
-            case HASH_SHA2_256:
-            case HASH_SHA2_512:
-                return LIBCR51SIGN_SUCCESS;
-            default:
-                return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE;
+            CPRINTS(ctx, "validate_transition: illegal image type\n");
+            return LIBCR51SIGN_ERROR_DEV_DOWNGRADE_DISALLOWED;
         }
     }
+    return LIBCR51SIGN_SUCCESS;
+}
 
-    // Determines digest size for a given hash_type.
-    // Returns error if hash_type is not supported.
-    static failure_reason get_hash_digest_size(enum hash_type type,
-                                               uint32_t* size)
+// If caller had provided read_and_hash_update call that, otherwise call
+// read and then update.
+
+static failure_reason read_and_hash_update(const struct libcr51sign_ctx* ctx,
+                                           const struct libcr51sign_intf* intf,
+                                           uint32_t offset, uint32_t size)
+{
+    uint8_t read_buffer[MAX_READ_SIZE];
+    int rv;
+    int read_size;
+
+    if (intf->read_and_hash_update)
     {
-        switch (type)
-        {
-            case HASH_SHA2_256:
-                *size = LIBCR51SIGN_SHA256_DIGEST_SIZE;
-                return LIBCR51SIGN_SUCCESS;
-            case HASH_SHA2_512:
-                *size = LIBCR51SIGN_SHA512_DIGEST_SIZE;
-                return LIBCR51SIGN_SUCCESS;
-            default:
-                return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE;
-        }
+        rv = intf->read_and_hash_update((void*)ctx, offset, size);
     }
-
-    // Determines hash struct size for a given hash_type.
-    // Returns error if hash_type is not supported.
-    static failure_reason get_hash_struct_size(enum hash_type type,
-                                               uint32_t* size)
+    else
     {
-        switch (type)
+        if (!intf->hash_update)
         {
-            case HASH_SHA2_256:
-                *size = sizeof(struct hash_sha256);
-                return LIBCR51SIGN_SUCCESS;
-            case HASH_SHA2_512:
-                *size = sizeof(struct hash_sha256);
-                return LIBCR51SIGN_SUCCESS;
-            default:
-                return LIBCR51SIGN_ERROR_INVALID_HASH_TYPE;
-        }
-    }
-
-    // Checks that:
-    //  - The signing key is trusted
-    //  - The target version is not denylisted
-    // If validating a staged update, also checks that:
-    //  - The target image family matches the current image family
-    //  - The image type transition is legal (i.e. dev -> *|| prod -> prod) or
-    //    alternatively that the hardware ID is allowlisted
-    // Assuming the caller has performed following:
-    // board_get_base_key_index();
-    // board_get_key_array
-    // Possible return codes:
-    // LIBCR51SIGN_SUCCESS = 0,
-    // LIBCR51SIGN_ERROR_RUNTIME_FAILURE = 1,
-    // LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR = 3,
-    // LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY = 4,
-    // LIBCR51SIGN_ERROR_IMAGE_TYPE_DISALLOWED = 5,
-
-    static failure_reason
-        validate_transition(const struct libcr51sign_ctx* ctx,
-                            const struct libcr51sign_intf* intf,
-                            uint32_t signature_struct_offset)
-    {
-        BUILD_ASSERT((offsetof(struct signature_rsa2048_pkcs15, modulus) ==
-                          SIGNATURE_OFFSET &&
-                      offsetof(struct signature_rsa3072_pkcs15, modulus) ==
-                          SIGNATURE_OFFSET &&
-                      offsetof(struct signature_rsa4096_pkcs15, modulus) ==
-                          SIGNATURE_OFFSET));
-
-        // Read up to the modulus.
-        enum
-        {
-            read_len = SIGNATURE_OFFSET
-        };
-        uint8_t buffer[read_len];
-        int rv;
-        rv = intf->read(ctx, signature_struct_offset, read_len, buffer);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx,
-                    "validate_transition: failed to read signature struct\n");
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-        if (*(uint32_t*)buffer != SIGNATURE_MAGIC)
-        {
-            CPRINTS(ctx, "validate_transition: bad signature magic\n");
-            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-        }
-
-        if (ctx->descriptor.image_family != ctx->current_image_family &&
-            ctx->descriptor.image_family != IMAGE_FAMILY_ALL &&
-            ctx->current_image_family != IMAGE_FAMILY_ALL)
-        {
-            CPRINTS(ctx, "validate_transition: invalid image family\n");
-            return LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY;
-        }
-
-        if (intf->is_production_mode == NULL)
-        {
-            CPRINTS(ctx, "validate_transition: missing is_production_mode\n");
+            CPRINTS(ctx, "read_and_hash_update: missing hash_update\n");
             return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
         }
-        if (intf->is_production_mode() &&
-            (ctx->descriptor.image_type == IMAGE_DEV))
+        do
         {
-            CPRINTS(ctx, "validate_transition: checking exemption allowlist\n");
-
-            // If function is NULL or if the function call return false, return
-            // error
-            if (intf->prod_to_dev_downgrade_allowed == NULL ||
-                !intf->prod_to_dev_downgrade_allowed())
+            read_size = size < MAX_READ_SIZE ? size : MAX_READ_SIZE;
+            rv = intf->read((void*)ctx, offset, read_size, read_buffer);
+            if (rv != LIBCR51SIGN_SUCCESS)
             {
-                CPRINTS(ctx, "validate_transition: illegal image type\n");
-                return LIBCR51SIGN_ERROR_DEV_DOWNGRADE_DISALLOWED;
+                return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
             }
-        }
-        return LIBCR51SIGN_SUCCESS;
+            rv = intf->hash_update((void*)ctx, read_buffer, read_size);
+            if (rv != LIBCR51SIGN_SUCCESS)
+            {
+                return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+            }
+            offset += read_size;
+            size -= read_size;
+        } while (size > 0);
+    }
+    return rv;
+}
+
+// Validates the image_region array, namely that:
+//  - The regions are aligned, contiguous & exhaustive
+//  - That the image descriptor resides in a static region
+//
+// If the array is consistent, proceeds to hash the static regions and
+// validates the hash. d_offset is the absolute image descriptor offset
+
+static failure_reason validate_payload_regions(
+    const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf,
+    uint32_t d_offset, struct libcr51sign_validated_regions* image_regions)
+{
+    // Allocate buffer to accomodate largest supported hash-type(SHA512)
+    uint8_t magic_and_digest[MEMBER_SIZE(struct hash_sha512, hash_magic) +
+                             LIBCR51SIGN_SHA512_DIGEST_SIZE];
+    uint8_t dcrypto_digest[LIBCR51SIGN_SHA512_DIGEST_SIZE];
+    uint32_t byte_count, region_count, image_size, hash_offset, digest_size;
+    uint32_t i;
+    uint8_t d_region_num = 0;
+    int rv;
+    const struct image_region* region;
+
+    if (image_regions == NULL)
+    {
+        CPRINTS(ctx, "Missing image region input\n");
+        return LIBCR51SIGN_ERROR_INVALID_REGION_INPUT;
     }
 
-    // If caller had provided read_and_hash_update call that, otherwise call
-    // read and then update.
+    BUILD_ASSERT((MEMBER_SIZE(struct hash_sha256, hash_magic) ==
+                  MEMBER_SIZE(struct hash_sha512, hash_magic)));
+    image_size = ctx->descriptor.image_size;
+    region_count = ctx->descriptor.region_count;
+    hash_offset = d_offset + sizeof(struct image_descriptor) +
+                  region_count * sizeof(struct image_region);
+    // Read the image_region array.
 
-    static failure_reason
-        read_and_hash_update(const struct libcr51sign_ctx* ctx,
-                             const struct libcr51sign_intf* intf,
-                             uint32_t offset, uint32_t size)
+    if (region_count > ARRAY_SIZE(image_regions->image_regions))
     {
-        uint8_t read_buffer[MAX_READ_SIZE];
-        int rv;
-        int read_size;
+        CPRINTS(ctx, "validate_payload_regions: "
+                     "ctx->descriptor.region_count is greater "
+                     "than LIBCR51SIGN_MAX_REGION_COUNT\n");
+        return LIBCR51SIGN_ERROR_INVALID_REGION_SIZE;
+    }
 
-        if (intf->read_and_hash_update)
+    rv = intf->read(ctx, d_offset + sizeof(struct image_descriptor),
+                    region_count * sizeof(struct image_region),
+                    (uint8_t*)&image_regions->image_regions);
+
+    image_regions->region_count = region_count;
+
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_payload_regions: failed to read region array\n");
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+    }
+
+    // Validate that the regions are contiguous & exhaustive.
+    for (i = 0, byte_count = 0; i < region_count; i++)
+    {
+        region = image_regions->image_regions + i;
+
+        CPRINTS(ctx, "validate_payload_regions: region #%d \"%s\" (%x - %x)\n",
+                i, (const char*)region->region_name, region->region_offset,
+                region->region_offset + region->region_size);
+        if ((region->region_offset % IMAGE_REGION_ALIGNMENT) != 0 ||
+            (region->region_size % IMAGE_REGION_ALIGNMENT) != 0)
         {
-            rv = intf->read_and_hash_update((void*)ctx, offset, size);
+            CPRINTS(ctx, "validate_payload_regions: regions must be sector "
+                         "aligned\n");
+            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
         }
-        else
+        if (region->region_offset != byte_count ||
+            region->region_size > image_size - byte_count)
         {
-            if (!intf->hash_update)
+            CPRINTS(ctx, "validate_payload_regions: invalid region array\n");
+            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+        }
+        byte_count += region->region_size;
+        // The image descriptor must be part of a static region.
+        if (d_offset >= region->region_offset && d_offset < byte_count)
+        {
+            d_region_num = i;
+            CPRINTS(ctx,
+                    "validate_payload_regions: image descriptor in region %d\n",
+                    i);
+            // The descriptor can't span regions.
+            if (ctx->descriptor.descriptor_area_size > byte_count ||
+                !(region->region_attributes & IMAGE_REGION_STATIC))
             {
-                CPRINTS(ctx, "read_and_hash_update: missing hash_update\n");
-                return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
+                CPRINTS(ctx,
+                        "validate_payload_regions: descriptor must reside in "
+                        "static region\n");
+                return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
             }
-            do
-            {
-                read_size = size < MAX_READ_SIZE ? size : MAX_READ_SIZE;
-                rv = intf->read((void*)ctx, offset, read_size, read_buffer);
-                if (rv != LIBCR51SIGN_SUCCESS)
-                {
-                    return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-                }
-                rv = intf->hash_update((void*)ctx, read_buffer, read_size);
-                if (rv != LIBCR51SIGN_SUCCESS)
-                {
-                    return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-                }
-                offset += read_size;
-                size -= read_size;
-            } while (size > 0);
         }
+    }
+    if (byte_count != image_size)
+    {
+        CPRINTS(ctx, "validate_payload_regions: invalid image size\n");
+        return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+    }
+
+    rv = get_hash_digest_size(ctx->descriptor.hash_type, &digest_size);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
         return rv;
     }
 
-    // Validates the image_region array, namely that:
-    //  - The regions are aligned, contiguous & exhaustive
-    //  - That the image descriptor resides in a static region
-    //
-    // If the array is consistent, proceeds to hash the static regions and
-    // validates the hash. d_offset is the absolute image descriptor offset
-
-    static failure_reason validate_payload_regions(
-        const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf,
-        uint32_t d_offset, struct libcr51sign_validated_regions* image_regions)
+    rv = intf->read(ctx, hash_offset,
+                    MEMBER_SIZE(struct hash_sha256, hash_magic) + digest_size,
+                    magic_and_digest);
+    if (rv != LIBCR51SIGN_SUCCESS)
     {
-        // Allocate buffer to accomodate largest supported hash-type(SHA512)
-        uint8_t magic_and_digest[MEMBER_SIZE(struct hash_sha512, hash_magic) +
-                                 LIBCR51SIGN_SHA512_DIGEST_SIZE];
-        uint8_t dcrypto_digest[LIBCR51SIGN_SHA512_DIGEST_SIZE];
-        uint32_t byte_count, region_count, image_size, hash_offset, digest_size;
-        uint32_t i;
-        uint8_t d_region_num = 0;
-        int rv;
-        const struct image_region* region;
-
-        if (image_regions == NULL)
-        {
-            CPRINTS(ctx, "Missing image region input\n");
-            return LIBCR51SIGN_ERROR_INVALID_REGION_INPUT;
-        }
-
-        BUILD_ASSERT((MEMBER_SIZE(struct hash_sha256, hash_magic) ==
-                      MEMBER_SIZE(struct hash_sha512, hash_magic)));
-        image_size = ctx->descriptor.image_size;
-        region_count = ctx->descriptor.region_count;
-        hash_offset = d_offset + sizeof(struct image_descriptor) +
-                      region_count * sizeof(struct image_region);
-        // Read the image_region array.
-
-        if (region_count > ARRAY_SIZE(image_regions->image_regions))
-        {
-            CPRINTS(ctx, "validate_payload_regions: "
-                         "ctx->descriptor.region_count is greater "
-                         "than LIBCR51SIGN_MAX_REGION_COUNT\n");
-            return LIBCR51SIGN_ERROR_INVALID_REGION_SIZE;
-        }
-
-        rv = intf->read(ctx, d_offset + sizeof(struct image_descriptor),
-                        region_count * sizeof(struct image_region),
-                        (uint8_t*)&image_regions->image_regions);
-
-        image_regions->region_count = region_count;
-
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx,
-                    "validate_payload_regions: failed to read region array\n");
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-
-        // Validate that the regions are contiguous & exhaustive.
-        for (i = 0, byte_count = 0; i < region_count; i++)
-        {
-            region = image_regions->image_regions + i;
-
-            CPRINTS(ctx,
-                    "validate_payload_regions: region #%d \"%s\" (%x - %x)\n",
-                    i, (const char*)region->region_name, region->region_offset,
-                    region->region_offset + region->region_size);
-            if ((region->region_offset % IMAGE_REGION_ALIGNMENT) != 0 ||
-                (region->region_size % IMAGE_REGION_ALIGNMENT) != 0)
-            {
-                CPRINTS(ctx, "validate_payload_regions: regions must be sector "
-                             "aligned\n");
-                return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-            }
-            if (region->region_offset != byte_count ||
-                region->region_size > image_size - byte_count)
-            {
-                CPRINTS(ctx,
-                        "validate_payload_regions: invalid region array\n");
-                return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-            }
-            byte_count += region->region_size;
-            // The image descriptor must be part of a static region.
-            if (d_offset >= region->region_offset && d_offset < byte_count)
-            {
-                d_region_num = i;
-                CPRINTS(
-                    ctx,
-                    "validate_payload_regions: image descriptor in region %d\n",
-                    i);
-                // The descriptor can't span regions.
-                if (ctx->descriptor.descriptor_area_size > byte_count ||
-                    !(region->region_attributes & IMAGE_REGION_STATIC))
-                {
-                    CPRINTS(
-                        ctx,
-                        "validate_payload_regions: descriptor must reside in "
-                        "static region\n");
-                    return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-                }
-            }
-        }
-        if (byte_count != image_size)
-        {
-            CPRINTS(ctx, "validate_payload_regions: invalid image size\n");
-            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-        }
-
-        rv = get_hash_digest_size(ctx->descriptor.hash_type, &digest_size);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return rv;
-        }
-
-        rv = intf->read(ctx, hash_offset,
-                        MEMBER_SIZE(struct hash_sha256, hash_magic) +
-                            digest_size,
-                        magic_and_digest);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(
-                ctx,
+        CPRINTS(ctx,
                 "validate_payload_regions: failed to read hash from flash\n");
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-        if (*(uint32_t*)magic_and_digest != HASH_MAGIC)
-        {
-            CPRINTS(ctx, "validate_payload_regions: bad hash magic\n");
-            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-        }
-        rv = intf->hash_init(ctx, ctx->descriptor.hash_type);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx, "validate_payload_regions: hash_init failed\n");
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-        for (i = 0; i < region_count; i++)
-        {
-            uint32_t hash_start, hash_size;
-            region = image_regions->image_regions + i;
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+    }
+    if (*(uint32_t*)magic_and_digest != HASH_MAGIC)
+    {
+        CPRINTS(ctx, "validate_payload_regions: bad hash magic\n");
+        return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+    }
+    rv = intf->hash_init(ctx, ctx->descriptor.hash_type);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_payload_regions: hash_init failed\n");
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+    }
+    for (i = 0; i < region_count; i++)
+    {
+        uint32_t hash_start, hash_size;
+        region = image_regions->image_regions + i;
 
-            if (!(region->region_attributes & IMAGE_REGION_STATIC))
+        if (!(region->region_attributes & IMAGE_REGION_STATIC))
+        {
+            continue;
+        }
+        hash_start = region->region_offset;
+        hash_size = region->region_size;
+
+        // Skip the descriptor.
+        do
+        {
+            if (i == d_region_num)
             {
-                continue;
+                hash_size = d_offset - hash_start;
             }
-            hash_start = region->region_offset;
-            hash_size = region->region_size;
 
-            // Skip the descriptor.
-            do
+            if (!hash_size)
             {
-                if (i == d_region_num)
-                {
-                    hash_size = d_offset - hash_start;
-                }
-
-                if (!hash_size)
-                {
-                    hash_start += ctx->descriptor.descriptor_area_size;
-                    hash_size = (region->region_offset + region->region_size -
-                                 hash_start);
-                }
-                CPRINTS("validate_payload_regions: hashing %s (%x - %x)\n",
-                        (const char*)region->region_name, hash_start,
-                        hash_start + hash_size);
-                // Read the image_region array.
-                rv = read_and_hash_update(ctx, intf, hash_start, hash_size);
-                if (rv != LIBCR51SIGN_SUCCESS)
-                {
-                    return rv;
-                }
-                hash_start += hash_size;
-            } while (hash_start != region->region_offset + region->region_size);
-        }
-        rv = intf->hash_final((void*)ctx, (uint8_t*)dcrypto_digest);
-
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-
-        if (memcmp(magic_and_digest +
-                       MEMBER_SIZE(struct hash_sha256, hash_magic),
-                   dcrypto_digest, digest_size))
-        {
-            CPRINTS(ctx, "validate_payload_regions: invalid hash\n");
-            return LIBCR51SIGN_ERROR_INVALID_HASH;
-        }
-        // Image is valid.
-        return LIBCR51SIGN_SUCCESS;
-    }
-
-    // Create empty image_regions to pass to validate_payload_regions
-    // Support validate_payload_regions_helper to remove image_regions as a
-    // required input.
-
-    static failure_reason
-        allocate_and_validate_payload_regions(const struct libcr51sign_ctx* ctx,
-                                              struct libcr51sign_intf* intf,
-                                              uint32_t d_offset)
-    {
-        struct libcr51sign_validated_regions image_regions;
-        return validate_payload_regions(ctx, intf, d_offset, &image_regions);
-    }
-
-    // Wrapper around validate_payload_regions to allow nullptr for
-    // image_regions. Calls allocate_and_validate_payload_regions when
-    // image_regions is nullptr to create placer holder image_regions.
-
-    static failure_reason validate_payload_regions_helper(
-        const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf,
-        uint32_t d_offset, struct libcr51sign_validated_regions* image_regions)
-    {
-        if (image_regions)
-        {
-            return validate_payload_regions(ctx, intf, d_offset, image_regions);
-        }
-
-        return allocate_and_validate_payload_regions(ctx, intf, d_offset);
-    }
-
-    // Check if the given signature_scheme is supported.
-    // Returns nonzero on error, zero on success
-
-    static failure_reason
-        is_signature_scheme_supported(enum signature_scheme scheme)
-    {
-        switch (scheme)
-        {
-            case SIGNATURE_RSA2048_PKCS15:
-            case SIGNATURE_RSA3072_PKCS15:
-            case SIGNATURE_RSA4096_PKCS15:
-            case SIGNATURE_RSA4096_PKCS15_SHA512:
-                return LIBCR51SIGN_SUCCESS;
-            default:
-                return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
-        }
-    }
-
-    // Returns size of signature struct size in |size|
-    // Returns nonzero on error, zero on success
-
-    static failure_reason
-        get_signature_struct_size(enum signature_scheme scheme, uint32_t* size)
-    {
-        switch (scheme)
-        {
-            case SIGNATURE_RSA2048_PKCS15:
-                *size = sizeof(struct signature_rsa2048_pkcs15);
-                return LIBCR51SIGN_SUCCESS;
-            case SIGNATURE_RSA3072_PKCS15:
-                *size = sizeof(struct signature_rsa3072_pkcs15);
-                return LIBCR51SIGN_SUCCESS;
-            case SIGNATURE_RSA4096_PKCS15:
-            case SIGNATURE_RSA4096_PKCS15_SHA512:
-                *size = sizeof(struct signature_rsa4096_pkcs15);
-                return LIBCR51SIGN_SUCCESS;
-            default:
-                return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
-        }
-    }
-
-    static failure_reason
-        get_signature_field_offset(enum signature_scheme scheme,
-                                   uint32_t* offset)
-    {
-        switch (scheme)
-        {
-            case SIGNATURE_RSA2048_PKCS15:
-                *offset = offsetof(struct signature_rsa2048_pkcs15, signature);
-                return LIBCR51SIGN_SUCCESS;
-            case SIGNATURE_RSA3072_PKCS15:
-                *offset = offsetof(struct signature_rsa3072_pkcs15, signature);
-                return LIBCR51SIGN_SUCCESS;
-            case SIGNATURE_RSA4096_PKCS15:
-            case SIGNATURE_RSA4096_PKCS15_SHA512:
-                *offset = offsetof(struct signature_rsa4096_pkcs15, signature);
-                return LIBCR51SIGN_SUCCESS;
-            default:
-                return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
-        }
-    }
-
-    // Validates the signature (of type scheme) read from "device" at
-    //"raw_signature_offset" with "public_key" over a SHA256/SHA512 digest of
-    // EEPROM area "data_offset:data_size".
-
-    static failure_reason validate_signature(
-        const struct libcr51sign_ctx* ctx, const struct libcr51sign_intf* intf,
-        uint32_t data_offset, uint32_t data_size, enum signature_scheme scheme,
-        uint32_t raw_signature_offset)
-    {
-        uint8_t signature[LIBCR51SIGN_MAX_SIGNATURE_SIZE];
-        uint16_t key_size;
-        uint32_t digest_size;
-        uint8_t dcrypto_digest[LIBCR51SIGN_SHA512_DIGEST_SIZE];
-        int rv;
-        enum hash_type hash_type;
-
-        if (!intf->hash_init)
-        {
-            CPRINTS(ctx, "validate_signature: missing hash_init\n");
-            return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
-        }
-        rv = get_hash_type_from_signature(scheme, &hash_type);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(
-                ctx,
-                "validate_payload_regions: hash_type from signature failed\n");
-            return rv;
-        }
-        rv = intf->hash_init(ctx, hash_type);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx, "validate_payload_regions: hash_init failed\n");
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-        rv = read_and_hash_update(ctx, intf, data_offset, data_size);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx, "validate_signature: hash_update failed\n");
-            return rv;
-        }
-        if (!intf->hash_final)
-        {
-            CPRINTS(ctx, "validate_signature: missing hash_final\n");
-            return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
-        }
-        rv = intf->hash_final((void*)ctx, dcrypto_digest);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx,
-                    "validate_signature: hash_final failed (status = %d)\n",
-                    rv);
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-        rv = get_key_size(scheme, &key_size);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return rv;
-        }
-
-        rv = intf->read(ctx, raw_signature_offset, key_size, signature);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(
-                ctx,
-                "validate_signature: failed to read signature (status = %d)\n",
-                rv);
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-        if (!intf->verify_signature)
-        {
-            CPRINTS(ctx, "validate_signature: missing verify_signature\n");
-            return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
-        }
-        rv = get_hash_digest_size(hash_type, &digest_size);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return rv;
-        }
-        rv = intf->verify_signature(ctx, scheme, signature, key_size,
-                                    dcrypto_digest, digest_size);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx,
-                    "validate_signature: verification failed (status = %d)\n",
-                    rv);
-            return LIBCR51SIGN_ERROR_INVALID_SIGNATURE;
-        }
-        CPRINTS(ctx, "validate_signature: verification succeeded\n");
-        return LIBCR51SIGN_SUCCESS;
-    }
-
-    // Sanity checks the image descriptor & validates its signature.
-    // This function does not validate the image_region array or image hash.
-    //
-    //@param[in] ctx  context which describes the image and holds opaque private
-    //                 data for the user of the library
-    //@param[in] intf  function pointers which interface to the current system
-    // and environment
-    //@param offset  Absolute image descriptor flash offset.
-    //@param relative_offset  Image descriptor offset relative to image start.
-    //@param max_size Maximum size of the flash space in bytes.
-    //@param descriptor  Output pointer to an image_descriptor struct
-
-    static failure_reason validate_descriptor(
-        const struct libcr51sign_ctx* ctx, const struct libcr51sign_intf* intf,
-        uint32_t offset, uint32_t relative_offset, uint32_t max_size)
-    {
-        uint32_t max_descriptor_size, signed_size, signature_scheme,
-            signature_offset;
-        uint32_t signature_struct_offset, signature_struct_size,
-            hash_struct_size;
-        int rv;
-
-        max_descriptor_size = max_size - relative_offset;
-        if (max_size < relative_offset ||
-            max_descriptor_size < sizeof(struct image_descriptor))
-        {
-            CPRINTS(ctx, "validate_descriptor: invalid arguments\n");
-            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-        }
-
-        rv = intf->read(ctx, offset, sizeof(ctx->descriptor),
-                        (uint8_t*)&ctx->descriptor);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx, "validate_descriptor: failed to read descriptor\n");
-            return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
-        }
-        if (ctx->descriptor.descriptor_magic != DESCRIPTOR_MAGIC ||
-            ctx->descriptor.descriptor_offset != relative_offset ||
-            ctx->descriptor.region_count == 0 ||
-            ctx->descriptor.descriptor_area_size > max_descriptor_size ||
-            ctx->descriptor.image_size > max_size)
-        {
-            CPRINTS(ctx, "validate_descriptor: invalid descriptor\n");
-            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-        }
-        if (intf->image_size_valid == NULL)
-        {
-            // Preserve original behavior of requiring exact image_size match if
-            // no operator is provided.
-            if (ctx->descriptor.image_size != max_size)
-            {
-                CPRINTS(ctx, "validate_descriptor: invalid image size\n");
-                return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+                hash_start += ctx->descriptor.descriptor_area_size;
+                hash_size =
+                    (region->region_offset + region->region_size - hash_start);
             }
-        }
-        else if (!intf->image_size_valid(ctx->descriptor.image_size))
-        {
-            CPRINTS(ctx, "validate_descriptor: invalid image size\n");
-            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-        }
-        if (ctx->descriptor.image_type != IMAGE_DEV &&
-            ctx->descriptor.image_type != IMAGE_PROD &&
-            ctx->descriptor.image_type != IMAGE_BREAKOUT &&
-            ctx->descriptor.image_type != IMAGE_TEST &&
-            ctx->descriptor.image_type != IMAGE_UNSIGNED_INTEGRITY)
-        {
-            CPRINTS(ctx, "validate_descriptor: bad image type\n");
-            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-        }
-        // Although the image_descriptor struct supports unauthenticated
-        // images, Haven will not allow it.
-        // Haven only supports SHA256 + RSA2048/RSA3072_PKCS15 currently.
-
-        signature_scheme = ctx->descriptor.signature_scheme;
-
-        rv = is_signature_scheme_supported(signature_scheme);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return rv;
-        }
-        rv = is_hash_type_supported(ctx->descriptor.hash_type);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            CPRINTS(ctx, "validate_payload_regions: invalid hash type\n");
-            return rv;
-        }
-        if (ctx->descriptor.descriptor_major > MAX_MAJOR_VERSION ||
-            ctx->descriptor.region_count > LIBCR51SIGN_MAX_REGION_COUNT)
-        {
-            CPRINTS(ctx, "validate_descriptor: unsupported descriptor\n");
-            return LIBCR51SIGN_ERROR_UNSUPPORTED_DESCRIPTOR;
-        }
-        rv = get_signature_struct_size(signature_scheme,
-                                       &signature_struct_size);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return rv;
-        }
-
-        // Compute the size of the signed portion of the image descriptor.
-        signed_size = sizeof(struct image_descriptor) +
-                      ctx->descriptor.region_count *
-                          sizeof(struct image_region);
-        rv = get_hash_struct_size(ctx->descriptor.hash_type, &hash_struct_size);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return rv;
-        }
-        signed_size += hash_struct_size;
-        if (ctx->descriptor.denylist_size)
-        {
-            signed_size += sizeof(struct denylist);
-            signed_size += ctx->descriptor.denylist_size *
-                           sizeof(struct denylist_record);
-        }
-        if (ctx->descriptor.blob_size)
-        {
-            signed_size += sizeof(struct blob);
-            // Previous additions are guaranteed not to overflow.
-            if (ctx->descriptor.blob_size >
-                ctx->descriptor.descriptor_area_size - signed_size)
-            {
-                CPRINTS(ctx, "validate_descriptor: invalid blob size (0x%x)\n",
-                        ctx->descriptor.blob_size);
-                return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-            }
-            signed_size += ctx->descriptor.blob_size;
-        }
-        if (signature_struct_size >
-            ctx->descriptor.descriptor_area_size - signed_size)
-        {
-            CPRINTS(ctx,
-                    "validate_descriptor: invalid descriptor area size "
-                    "(expected = 0x%x, actual = 0x%x)\n",
-                    ctx->descriptor.descriptor_area_size,
-                    signed_size + signature_struct_size);
-            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
-        }
-        signature_struct_offset = signed_size;
-        // Omit the actual signature.
-        rv = get_signature_field_offset(signature_scheme, &signature_offset);
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return rv;
-        }
-        signed_size += signature_offset;
-
-        // Lookup key & validate transition.
-        rv = validate_transition(ctx, intf, offset + signature_struct_offset);
-
-        if (rv != LIBCR51SIGN_SUCCESS)
-        {
-            return rv;
-        }
-        return validate_signature(ctx, intf, offset, signed_size,
-                                  signature_scheme, offset + signed_size);
-    }
-
-    // Scans the external EEPROM for a magic value at "alignment" boundaries.
-    //
-    //@param device  Handle to the external EEPROM.
-    //@param magic   8-byte pattern to search for.
-    //@param start_offset  Offset to begin searching at.
-    //@param limit   Exclusive address (e.g. EEPROM size).
-    //@param alignment   Alignment boundaries (POW2) to search on.
-    //@param header_offset   Location to place the new header offset.
-    //@return LIBCR51SIGN_SUCCESS (or non-zero on error).
-
-    int scan_for_magic_8(const struct libcr51sign_ctx* ctx,
-                         const struct libcr51sign_intf* intf, uint64_t magic,
-                         uint32_t start_offset, uint32_t limit,
-                         uint32_t alignment, uint32_t* header_offset)
-    {
-        uint64_t read_data;
-        uint32_t offset;
-        int rv;
-
-        if (limit <= start_offset || limit > ctx->end_offset ||
-            limit < sizeof(magic) || !POWER_OF_TWO(alignment))
-        {
-            return LIBCR51SIGN_ERROR_INVALID_ARGUMENT;
-        }
-
-        if (!intf->read)
-        {
-            CPRINTS(ctx, "scan_for_magic_8: missing intf->read\n");
-            return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
-        }
-        // Align start_offset to the next valid boundary.
-        start_offset = ((start_offset - 1) & ~(alignment - 1)) + alignment;
-        for (offset = start_offset; offset < limit - sizeof(magic);
-             offset += alignment)
-        {
-            rv = intf->read((void*)ctx, offset, sizeof(read_data),
-                            (uint8_t*)&read_data);
+            CPRINTS("validate_payload_regions: hashing %s (%x - %x)\n",
+                    (const char*)region->region_name, hash_start,
+                    hash_start + hash_size);
+            // Read the image_region array.
+            rv = read_and_hash_update(ctx, intf, hash_start, hash_size);
             if (rv != LIBCR51SIGN_SUCCESS)
             {
                 return rv;
             }
-            if (read_data == magic)
-            {
-                if (header_offset)
-                {
-                    *header_offset = offset;
-                }
-                return LIBCR51SIGN_SUCCESS;
-            }
-        }
-        // Failed to locate magic.
-        return LIBCR51SIGN_ERROR_FAILED_TO_LOCATE_MAGIC;
+            hash_start += hash_size;
+        } while (hash_start != region->region_offset + region->region_size);
+    }
+    rv = intf->hash_final((void*)ctx, (uint8_t*)dcrypto_digest);
+
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
     }
 
-    // Check whether the signature on the image is valid.
-    // Validates the authenticity of an EEPROM image. Scans for & validates the
-    // signature on the image descriptor. If the descriptor validates, hashes
-    // the rest of the image to verify its integrity.
-    //
-    // @param[in] ctx - context which describes the image and holds opaque
-    // private
-    //                 data for the user of the library
-    // @param[in] intf - function pointers which interface to the current system
-    //                  and environment
-    // @param[out] image_regions - image_region pointer to an array for the
-    // output
-    //
-    // @return nonzero on error, zero on success
-
-    failure_reason libcr51sign_validate(
-        const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf,
-        struct libcr51sign_validated_regions* image_regions)
+    if (memcmp(magic_and_digest + MEMBER_SIZE(struct hash_sha256, hash_magic),
+               dcrypto_digest, digest_size))
     {
-        uint32_t image_limit = 0;
-        int rv, rv_first_desc = LIBCR51SIGN_SUCCESS;
-        uint32_t descriptor_offset;
+        CPRINTS(ctx, "validate_payload_regions: invalid hash\n");
+        return LIBCR51SIGN_ERROR_INVALID_HASH;
+    }
+    // Image is valid.
+    return LIBCR51SIGN_SUCCESS;
+}
 
-        if (!ctx)
+// Create empty image_regions to pass to validate_payload_regions
+// Support validate_payload_regions_helper to remove image_regions as a
+// required input.
+
+static failure_reason
+    allocate_and_validate_payload_regions(const struct libcr51sign_ctx* ctx,
+                                          struct libcr51sign_intf* intf,
+                                          uint32_t d_offset)
+{
+    struct libcr51sign_validated_regions image_regions;
+    return validate_payload_regions(ctx, intf, d_offset, &image_regions);
+}
+
+// Wrapper around validate_payload_regions to allow nullptr for
+// image_regions. Calls allocate_and_validate_payload_regions when
+// image_regions is nullptr to create placer holder image_regions.
+
+static failure_reason validate_payload_regions_helper(
+    const struct libcr51sign_ctx* ctx, struct libcr51sign_intf* intf,
+    uint32_t d_offset, struct libcr51sign_validated_regions* image_regions)
+{
+    if (image_regions)
+    {
+        return validate_payload_regions(ctx, intf, d_offset, image_regions);
+    }
+
+    return allocate_and_validate_payload_regions(ctx, intf, d_offset);
+}
+
+// Check if the given signature_scheme is supported.
+// Returns nonzero on error, zero on success
+
+static failure_reason
+    is_signature_scheme_supported(enum signature_scheme scheme)
+{
+    switch (scheme)
+    {
+        case SIGNATURE_RSA2048_PKCS15:
+        case SIGNATURE_RSA3072_PKCS15:
+        case SIGNATURE_RSA4096_PKCS15:
+        case SIGNATURE_RSA4096_PKCS15_SHA512:
+            return LIBCR51SIGN_SUCCESS;
+        default:
+            return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
+    }
+}
+
+// Returns size of signature struct size in |size|
+// Returns nonzero on error, zero on success
+
+static failure_reason get_signature_struct_size(enum signature_scheme scheme,
+                                                uint32_t* size)
+{
+    switch (scheme)
+    {
+        case SIGNATURE_RSA2048_PKCS15:
+            *size = sizeof(struct signature_rsa2048_pkcs15);
+            return LIBCR51SIGN_SUCCESS;
+        case SIGNATURE_RSA3072_PKCS15:
+            *size = sizeof(struct signature_rsa3072_pkcs15);
+            return LIBCR51SIGN_SUCCESS;
+        case SIGNATURE_RSA4096_PKCS15:
+        case SIGNATURE_RSA4096_PKCS15_SHA512:
+            *size = sizeof(struct signature_rsa4096_pkcs15);
+            return LIBCR51SIGN_SUCCESS;
+        default:
+            return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
+    }
+}
+
+static failure_reason get_signature_field_offset(enum signature_scheme scheme,
+                                                 uint32_t* offset)
+{
+    switch (scheme)
+    {
+        case SIGNATURE_RSA2048_PKCS15:
+            *offset = offsetof(struct signature_rsa2048_pkcs15, signature);
+            return LIBCR51SIGN_SUCCESS;
+        case SIGNATURE_RSA3072_PKCS15:
+            *offset = offsetof(struct signature_rsa3072_pkcs15, signature);
+            return LIBCR51SIGN_SUCCESS;
+        case SIGNATURE_RSA4096_PKCS15:
+        case SIGNATURE_RSA4096_PKCS15_SHA512:
+            *offset = offsetof(struct signature_rsa4096_pkcs15, signature);
+            return LIBCR51SIGN_SUCCESS;
+        default:
+            return LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME;
+    }
+}
+
+// Validates the signature (of type scheme) read from "device" at
+//"raw_signature_offset" with "public_key" over a SHA256/SHA512 digest of
+// EEPROM area "data_offset:data_size".
+
+static failure_reason validate_signature(const struct libcr51sign_ctx* ctx,
+                                         const struct libcr51sign_intf* intf,
+                                         uint32_t data_offset,
+                                         uint32_t data_size,
+                                         enum signature_scheme scheme,
+                                         uint32_t raw_signature_offset)
+{
+    uint8_t signature[LIBCR51SIGN_MAX_SIGNATURE_SIZE];
+    uint16_t key_size;
+    uint32_t digest_size;
+    uint8_t dcrypto_digest[LIBCR51SIGN_SHA512_DIGEST_SIZE];
+    int rv;
+    enum hash_type hash_type;
+
+    if (!intf->hash_init)
+    {
+        CPRINTS(ctx, "validate_signature: missing hash_init\n");
+        return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
+    }
+    rv = get_hash_type_from_signature(scheme, &hash_type);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx,
+                "validate_payload_regions: hash_type from signature failed\n");
+        return rv;
+    }
+    rv = intf->hash_init(ctx, hash_type);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_payload_regions: hash_init failed\n");
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+    }
+    rv = read_and_hash_update(ctx, intf, data_offset, data_size);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_signature: hash_update failed\n");
+        return rv;
+    }
+    if (!intf->hash_final)
+    {
+        CPRINTS(ctx, "validate_signature: missing hash_final\n");
+        return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
+    }
+    rv = intf->hash_final((void*)ctx, dcrypto_digest);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_signature: hash_final failed (status = %d)\n",
+                rv);
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+    }
+    rv = get_key_size(scheme, &key_size);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        return rv;
+    }
+
+    rv = intf->read(ctx, raw_signature_offset, key_size, signature);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx,
+                "validate_signature: failed to read signature (status = %d)\n",
+                rv);
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+    }
+    if (!intf->verify_signature)
+    {
+        CPRINTS(ctx, "validate_signature: missing verify_signature\n");
+        return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
+    }
+    rv = get_hash_digest_size(hash_type, &digest_size);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        return rv;
+    }
+    rv = intf->verify_signature(ctx, scheme, signature, key_size,
+                                dcrypto_digest, digest_size);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_signature: verification failed (status = %d)\n",
+                rv);
+        return LIBCR51SIGN_ERROR_INVALID_SIGNATURE;
+    }
+    CPRINTS(ctx, "validate_signature: verification succeeded\n");
+    return LIBCR51SIGN_SUCCESS;
+}
+
+// Sanity checks the image descriptor & validates its signature.
+// This function does not validate the image_region array or image hash.
+//
+//@param[in] ctx  context which describes the image and holds opaque private
+//                 data for the user of the library
+//@param[in] intf  function pointers which interface to the current system
+// and environment
+//@param offset  Absolute image descriptor flash offset.
+//@param relative_offset  Image descriptor offset relative to image start.
+//@param max_size Maximum size of the flash space in bytes.
+//@param descriptor  Output pointer to an image_descriptor struct
+
+static failure_reason validate_descriptor(const struct libcr51sign_ctx* ctx,
+                                          const struct libcr51sign_intf* intf,
+                                          uint32_t offset,
+                                          uint32_t relative_offset,
+                                          uint32_t max_size)
+{
+    uint32_t max_descriptor_size, signed_size, signature_scheme,
+        signature_offset;
+    uint32_t signature_struct_offset, signature_struct_size, hash_struct_size;
+    int rv;
+
+    max_descriptor_size = max_size - relative_offset;
+    if (max_size < relative_offset ||
+        max_descriptor_size < sizeof(struct image_descriptor))
+    {
+        CPRINTS(ctx, "validate_descriptor: invalid arguments\n");
+        return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+    }
+
+    rv = intf->read(ctx, offset, sizeof(ctx->descriptor),
+                    (uint8_t*)&ctx->descriptor);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_descriptor: failed to read descriptor\n");
+        return LIBCR51SIGN_ERROR_RUNTIME_FAILURE;
+    }
+    if (ctx->descriptor.descriptor_magic != DESCRIPTOR_MAGIC ||
+        ctx->descriptor.descriptor_offset != relative_offset ||
+        ctx->descriptor.region_count == 0 ||
+        ctx->descriptor.descriptor_area_size > max_descriptor_size ||
+        ctx->descriptor.image_size > max_size)
+    {
+        CPRINTS(ctx, "validate_descriptor: invalid descriptor\n");
+        return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+    }
+    if (intf->image_size_valid == NULL)
+    {
+        // Preserve original behavior of requiring exact image_size match if
+        // no operator is provided.
+        if (ctx->descriptor.image_size != max_size)
         {
-            CPRINTS(ctx, "Missing context\n");
-            return LIBCR51SIGN_ERROR_INVALID_CONTEXT;
+            CPRINTS(ctx, "validate_descriptor: invalid image size\n");
+            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
         }
-        else if (!intf)
+    }
+    else if (!intf->image_size_valid(ctx->descriptor.image_size))
+    {
+        CPRINTS(ctx, "validate_descriptor: invalid image size\n");
+        return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+    }
+    if (ctx->descriptor.image_type != IMAGE_DEV &&
+        ctx->descriptor.image_type != IMAGE_PROD &&
+        ctx->descriptor.image_type != IMAGE_BREAKOUT &&
+        ctx->descriptor.image_type != IMAGE_TEST &&
+        ctx->descriptor.image_type != IMAGE_UNSIGNED_INTEGRITY)
+    {
+        CPRINTS(ctx, "validate_descriptor: bad image type\n");
+        return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+    }
+    // Although the image_descriptor struct supports unauthenticated
+    // images, Haven will not allow it.
+    // Haven only supports SHA256 + RSA2048/RSA3072_PKCS15 currently.
+
+    signature_scheme = ctx->descriptor.signature_scheme;
+
+    rv = is_signature_scheme_supported(signature_scheme);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        return rv;
+    }
+    rv = is_hash_type_supported(ctx->descriptor.hash_type);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate_payload_regions: invalid hash type\n");
+        return rv;
+    }
+    if (ctx->descriptor.descriptor_major > MAX_MAJOR_VERSION ||
+        ctx->descriptor.region_count > LIBCR51SIGN_MAX_REGION_COUNT)
+    {
+        CPRINTS(ctx, "validate_descriptor: unsupported descriptor\n");
+        return LIBCR51SIGN_ERROR_UNSUPPORTED_DESCRIPTOR;
+    }
+    rv = get_signature_struct_size(signature_scheme, &signature_struct_size);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        return rv;
+    }
+
+    // Compute the size of the signed portion of the image descriptor.
+    signed_size = sizeof(struct image_descriptor) +
+                  ctx->descriptor.region_count * sizeof(struct image_region);
+    rv = get_hash_struct_size(ctx->descriptor.hash_type, &hash_struct_size);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        return rv;
+    }
+    signed_size += hash_struct_size;
+    if (ctx->descriptor.denylist_size)
+    {
+        signed_size += sizeof(struct denylist);
+        signed_size += ctx->descriptor.denylist_size *
+                       sizeof(struct denylist_record);
+    }
+    if (ctx->descriptor.blob_size)
+    {
+        signed_size += sizeof(struct blob);
+        // Previous additions are guaranteed not to overflow.
+        if (ctx->descriptor.blob_size >
+            ctx->descriptor.descriptor_area_size - signed_size)
         {
-            CPRINTS(ctx, "Missing interface\n");
-            return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
+            CPRINTS(ctx, "validate_descriptor: invalid blob size (0x%x)\n",
+                    ctx->descriptor.blob_size);
+            return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
         }
+        signed_size += ctx->descriptor.blob_size;
+    }
+    if (signature_struct_size >
+        ctx->descriptor.descriptor_area_size - signed_size)
+    {
+        CPRINTS(ctx,
+                "validate_descriptor: invalid descriptor area size "
+                "(expected = 0x%x, actual = 0x%x)\n",
+                ctx->descriptor.descriptor_area_size,
+                signed_size + signature_struct_size);
+        return LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR;
+    }
+    signature_struct_offset = signed_size;
+    // Omit the actual signature.
+    rv = get_signature_field_offset(signature_scheme, &signature_offset);
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        return rv;
+    }
+    signed_size += signature_offset;
 
-        rv = scan_for_magic_8(ctx, intf, DESCRIPTOR_MAGIC, ctx->start_offset,
-                              ctx->end_offset, DESCRIPTOR_ALIGNMENT,
-                              &descriptor_offset);
-        while (rv == LIBCR51SIGN_SUCCESS)
+    // Lookup key & validate transition.
+    rv = validate_transition(ctx, intf, offset + signature_struct_offset);
+
+    if (rv != LIBCR51SIGN_SUCCESS)
+    {
+        return rv;
+    }
+    return validate_signature(ctx, intf, offset, signed_size, signature_scheme,
+                              offset + signed_size);
+}
+
+// Scans the external EEPROM for a magic value at "alignment" boundaries.
+//
+//@param device  Handle to the external EEPROM.
+//@param magic   8-byte pattern to search for.
+//@param start_offset  Offset to begin searching at.
+//@param limit   Exclusive address (e.g. EEPROM size).
+//@param alignment   Alignment boundaries (POW2) to search on.
+//@param header_offset   Location to place the new header offset.
+//@return LIBCR51SIGN_SUCCESS (or non-zero on error).
+
+int scan_for_magic_8(const struct libcr51sign_ctx* ctx,
+                     const struct libcr51sign_intf* intf, uint64_t magic,
+                     uint32_t start_offset, uint32_t limit, uint32_t alignment,
+                     uint32_t* header_offset)
+{
+    uint64_t read_data;
+    uint32_t offset;
+    int rv;
+
+    if (limit <= start_offset || limit > ctx->end_offset ||
+        limit < sizeof(magic) || !POWER_OF_TWO(alignment))
+    {
+        return LIBCR51SIGN_ERROR_INVALID_ARGUMENT;
+    }
+
+    if (!intf->read)
+    {
+        CPRINTS(ctx, "scan_for_magic_8: missing intf->read\n");
+        return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
+    }
+    // Align start_offset to the next valid boundary.
+    start_offset = ((start_offset - 1) & ~(alignment - 1)) + alignment;
+    for (offset = start_offset; offset < limit - sizeof(magic);
+         offset += alignment)
+    {
+        rv = intf->read((void*)ctx, offset, sizeof(read_data),
+                        (uint8_t*)&read_data);
+        if (rv != LIBCR51SIGN_SUCCESS)
         {
-            CPRINTS(ctx, "validate: potential image descriptor found @%x\n",
-                    descriptor_offset);
-            // Validation is split into 2 functions to minimize
-            // stack usage.
-
-            rv = validate_descriptor(ctx, intf, descriptor_offset,
-                                     descriptor_offset - ctx->start_offset,
-                                     ctx->end_offset - ctx->start_offset);
-            if (rv != LIBCR51SIGN_SUCCESS)
+            return rv;
+        }
+        if (read_data == magic)
+        {
+            if (header_offset)
             {
-                CPRINTS(ctx, "validate: validate_descriptor() failed ec%d\n",
-                        rv);
+                *header_offset = offset;
             }
+            return LIBCR51SIGN_SUCCESS;
+        }
+    }
+    // Failed to locate magic.
+    return LIBCR51SIGN_ERROR_FAILED_TO_LOCATE_MAGIC;
+}
 
+// Check whether the signature on the image is valid.
+// Validates the authenticity of an EEPROM image. Scans for & validates the
+// signature on the image descriptor. If the descriptor validates, hashes
+// the rest of the image to verify its integrity.
+//
+// @param[in] ctx - context which describes the image and holds opaque
+// private
+//                 data for the user of the library
+// @param[in] intf - function pointers which interface to the current system
+//                  and environment
+// @param[out] image_regions - image_region pointer to an array for the
+// output
+//
+// @return nonzero on error, zero on success
+
+failure_reason
+    libcr51sign_validate(const struct libcr51sign_ctx* ctx,
+                         struct libcr51sign_intf* intf,
+                         struct libcr51sign_validated_regions* image_regions)
+{
+    uint32_t image_limit = 0;
+    int rv, rv_first_desc = LIBCR51SIGN_SUCCESS;
+    uint32_t descriptor_offset;
+
+    if (!ctx)
+    {
+        CPRINTS(ctx, "Missing context\n");
+        return LIBCR51SIGN_ERROR_INVALID_CONTEXT;
+    }
+    else if (!intf)
+    {
+        CPRINTS(ctx, "Missing interface\n");
+        return LIBCR51SIGN_ERROR_INVALID_INTERFACE;
+    }
+
+    rv = scan_for_magic_8(ctx, intf, DESCRIPTOR_MAGIC, ctx->start_offset,
+                          ctx->end_offset, DESCRIPTOR_ALIGNMENT,
+                          &descriptor_offset);
+    while (rv == LIBCR51SIGN_SUCCESS)
+    {
+        CPRINTS(ctx, "validate: potential image descriptor found @%x\n",
+                descriptor_offset);
+        // Validation is split into 2 functions to minimize
+        // stack usage.
+
+        rv = validate_descriptor(ctx, intf, descriptor_offset,
+                                 descriptor_offset - ctx->start_offset,
+                                 ctx->end_offset - ctx->start_offset);
+        if (rv != LIBCR51SIGN_SUCCESS)
+        {
+            CPRINTS(ctx, "validate: validate_descriptor() failed ec%d\n", rv);
+        }
+
+        if (rv == LIBCR51SIGN_SUCCESS)
+        {
+            rv = validate_payload_regions_helper(ctx, intf, descriptor_offset,
+                                                 image_regions);
             if (rv == LIBCR51SIGN_SUCCESS)
             {
-                rv = validate_payload_regions_helper(
-                    ctx, intf, descriptor_offset, image_regions);
-                if (rv == LIBCR51SIGN_SUCCESS)
-                {
-                    CPRINTS(ctx, "validate: success!\n");
-                    return rv;
-                }
-                CPRINTS(ctx,
-                        "validate: validate_payload_regions() failed ec%d\n",
-                        rv);
+                CPRINTS(ctx, "validate: success!\n");
+                return rv;
             }
-            // Store the first desc fail reason if any
-            if (rv != LIBCR51SIGN_SUCCESS &&
-                rv_first_desc == LIBCR51SIGN_SUCCESS)
-                rv_first_desc = rv;
-
-            // scan_for_magic_8() will round up to the next aligned boundary.
-            descriptor_offset++;
-            image_limit = ctx->end_offset - ctx->start_offset;
-            rv = scan_for_magic_8(ctx, intf, DESCRIPTOR_MAGIC,
-                                  descriptor_offset, image_limit,
-                                  DESCRIPTOR_ALIGNMENT, &descriptor_offset);
+            CPRINTS(ctx, "validate: validate_payload_regions() failed ec%d\n",
+                    rv);
         }
-        CPRINTS(ctx, "validate: failed to validate image ec%d\n", rv);
-        // If desc validation failed for some reason then return that reason
-        if (rv_first_desc != LIBCR51SIGN_SUCCESS)
-            return rv_first_desc;
-        else
-            return rv;
+        // Store the first desc fail reason if any
+        if (rv != LIBCR51SIGN_SUCCESS && rv_first_desc == LIBCR51SIGN_SUCCESS)
+            rv_first_desc = rv;
+
+        // scan_for_magic_8() will round up to the next aligned boundary.
+        descriptor_offset++;
+        image_limit = ctx->end_offset - ctx->start_offset;
+        rv = scan_for_magic_8(ctx, intf, DESCRIPTOR_MAGIC, descriptor_offset,
+                              image_limit, DESCRIPTOR_ALIGNMENT,
+                              &descriptor_offset);
     }
+    CPRINTS(ctx, "validate: failed to validate image ec%d\n", rv);
+    // If desc validation failed for some reason then return that reason
+    if (rv_first_desc != LIBCR51SIGN_SUCCESS)
+        return rv_first_desc;
+    else
+        return rv;
+}
 
-    // @func to returns the libcr51sign error code as a string
-    // @param[in] ec - Error code
-    // @return error code in string format
+// @func to returns the libcr51sign error code as a string
+// @param[in] ec - Error code
+// @return error code in string format
 
-    const char* libcr51sign_errorcode_to_string(failure_reason ec)
+const char* libcr51sign_errorcode_to_string(failure_reason ec)
+{
+    switch (ec)
     {
-        switch (ec)
-        {
-            case LIBCR51SIGN_SUCCESS:
-                return "Success";
-            case LIBCR51SIGN_ERROR_RUNTIME_FAILURE:
-                return "Runtime Error Failure";
-            case LIBCR51SIGN_ERROR_UNSUPPORTED_DESCRIPTOR:
-                return "Unsupported descriptor";
-            case LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR:
-                return "Invalid descriptor";
-            case LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY:
-                return "Invalid image family";
-            case LIBCR51SIGN_ERROR_IMAGE_TYPE_DISALLOWED:
-                return "Image type disallowed";
-            case LIBCR51SIGN_ERROR_DEV_DOWNGRADE_DISALLOWED:
-                return "Dev downgrade disallowed";
-            case LIBCR51SIGN_ERROR_UNTRUSTED_KEY:
-                return "Untrusted key";
-            case LIBCR51SIGN_ERROR_INVALID_SIGNATURE:
-                return "Invalid signature";
-            case LIBCR51SIGN_ERROR_INVALID_HASH:
-                return "Invalid hash";
-            case LIBCR51SIGN_ERROR_INVALID_HASH_TYPE:
-                return "Invalid hash type";
-            case LIBCR51SIGN_ERROR_INVALID_ARGUMENT:
-                return "Invalid Argument";
-            case LIBCR51SIGN_ERROR_FAILED_TO_LOCATE_MAGIC:
-                return "Failed to locate descriptor";
-            case LIBCR51SIGN_ERROR_INVALID_CONTEXT:
-                return "Invalid context";
-            case LIBCR51SIGN_ERROR_INVALID_INTERFACE:
-                return "Invalid interface";
-            case LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME:
-                return "Invalid signature scheme";
-            case LIBCR51SIGN_ERROR_INVALID_REGION_INPUT:
-                return "Invalid image region input";
-            case LIBCR51SIGN_ERROR_INVALID_REGION_SIZE:
-                return "Invalid image region size";
-            default:
-                return "Unknown error";
-        }
+        case LIBCR51SIGN_SUCCESS:
+            return "Success";
+        case LIBCR51SIGN_ERROR_RUNTIME_FAILURE:
+            return "Runtime Error Failure";
+        case LIBCR51SIGN_ERROR_UNSUPPORTED_DESCRIPTOR:
+            return "Unsupported descriptor";
+        case LIBCR51SIGN_ERROR_INVALID_DESCRIPTOR:
+            return "Invalid descriptor";
+        case LIBCR51SIGN_ERROR_INVALID_IMAGE_FAMILY:
+            return "Invalid image family";
+        case LIBCR51SIGN_ERROR_IMAGE_TYPE_DISALLOWED:
+            return "Image type disallowed";
+        case LIBCR51SIGN_ERROR_DEV_DOWNGRADE_DISALLOWED:
+            return "Dev downgrade disallowed";
+        case LIBCR51SIGN_ERROR_UNTRUSTED_KEY:
+            return "Untrusted key";
+        case LIBCR51SIGN_ERROR_INVALID_SIGNATURE:
+            return "Invalid signature";
+        case LIBCR51SIGN_ERROR_INVALID_HASH:
+            return "Invalid hash";
+        case LIBCR51SIGN_ERROR_INVALID_HASH_TYPE:
+            return "Invalid hash type";
+        case LIBCR51SIGN_ERROR_INVALID_ARGUMENT:
+            return "Invalid Argument";
+        case LIBCR51SIGN_ERROR_FAILED_TO_LOCATE_MAGIC:
+            return "Failed to locate descriptor";
+        case LIBCR51SIGN_ERROR_INVALID_CONTEXT:
+            return "Invalid context";
+        case LIBCR51SIGN_ERROR_INVALID_INTERFACE:
+            return "Invalid interface";
+        case LIBCR51SIGN_ERROR_INVALID_SIG_SCHEME:
+            return "Invalid signature scheme";
+        case LIBCR51SIGN_ERROR_INVALID_REGION_INPUT:
+            return "Invalid image region input";
+        case LIBCR51SIGN_ERROR_INVALID_REGION_SIZE:
+            return "Invalid image region size";
+        default:
+            return "Unknown error";
     }
+}
 
 #ifdef __cplusplus
 } //  extern "C"