diff --git a/oem/ibm/libpldmresponder/file_io_type_cert.cpp b/oem/ibm/libpldmresponder/file_io_type_cert.cpp
new file mode 100644
index 0000000..aef3f4c
--- /dev/null
+++ b/oem/ibm/libpldmresponder/file_io_type_cert.cpp
@@ -0,0 +1,132 @@
+#include "file_io_type_cert.hpp"
+
+#include "utils.hpp"
+
+#include <stdint.h>
+
+#include <iostream>
+
+#include "libpldm/base.h"
+#include "oem/ibm/libpldm/file_io.h"
+
+namespace pldm
+{
+namespace responder
+{
+
+static constexpr auto csrFilePath = "/var/lib/bmcweb/CSR";
+static constexpr auto rootCertPath = "/var/lib/bmcweb/RootCert";
+static constexpr auto clientCertPath = "/var/lib/bmcweb/ClientCert";
+
+CertMap CertHandler::certMap;
+
+int CertHandler::writeFromMemory(uint32_t offset, uint32_t length,
+                                 uint64_t address)
+{
+    auto it = certMap.find(certType);
+    if (it == certMap.end())
+    {
+        std::cerr << "file for type " << certType << " doesn't exist\n";
+        return PLDM_ERROR;
+    }
+
+    auto fd = std::get<0>(it->second);
+    auto& remSize = std::get<1>(it->second);
+    auto rc = transferFileData(fd, false, offset, length, address);
+    if (rc == PLDM_SUCCESS)
+    {
+        remSize -= length;
+        if (!remSize)
+        {
+            close(fd);
+            certMap.erase(it);
+        }
+    }
+    return rc;
+}
+
+int CertHandler::readIntoMemory(uint32_t offset, uint32_t& length,
+                                uint64_t address)
+{
+    if (certType != PLDM_FILE_TYPE_CERT_SIGNING_REQUEST)
+    {
+        return PLDM_ERROR_INVALID_DATA;
+    }
+    return transferFileData(csrFilePath, true, offset, length, address);
+}
+
+int CertHandler::read(uint32_t offset, uint32_t& length, Response& response)
+{
+    if (certType != PLDM_FILE_TYPE_CERT_SIGNING_REQUEST)
+    {
+        return PLDM_ERROR_INVALID_DATA;
+    }
+    return readFile(csrFilePath, offset, length, response);
+}
+
+int CertHandler::write(const char* buffer, uint32_t offset, uint32_t& length)
+{
+    auto it = certMap.find(certType);
+    if (it == certMap.end())
+    {
+        std::cerr << "file for type " << certType << " doesn't exist\n";
+        return PLDM_ERROR;
+    }
+
+    auto fd = std::get<0>(it->second);
+    int rc = lseek(fd, offset, SEEK_SET);
+    if (rc == -1)
+    {
+        std::cerr << "lseek failed, ERROR=" << errno << ", OFFSET=" << offset
+                  << "\n";
+        return PLDM_ERROR;
+    }
+    rc = ::write(fd, buffer, length);
+    if (rc == -1)
+    {
+        std::cerr << "file write failed, ERROR=" << errno
+                  << ", LENGTH=" << length << ", OFFSET=" << offset << "\n";
+        return PLDM_ERROR;
+    }
+    length = rc;
+    auto& remSize = std::get<1>(it->second);
+    remSize -= length;
+    if (!remSize)
+    {
+        close(fd);
+        certMap.erase(it);
+    }
+    return PLDM_SUCCESS;
+}
+
+int CertHandler::newFileAvailable(uint64_t length)
+{
+    static constexpr auto vmiCertPath = "/var/lib/bmcweb";
+    fs::create_directories(vmiCertPath);
+    int fileFd = -1;
+    int flags = O_WRONLY | O_CREAT | O_TRUNC;
+
+    if (certType == PLDM_FILE_TYPE_CERT_SIGNING_REQUEST)
+    {
+        return PLDM_ERROR_INVALID_DATA;
+    }
+    if (certType == PLDM_FILE_TYPE_SIGNED_CERT)
+    {
+        fileFd = open(clientCertPath, flags);
+    }
+    else if (certType == PLDM_FILE_TYPE_ROOT_CERT)
+    {
+        fileFd = open(rootCertPath, flags);
+    }
+    if (fileFd == -1)
+    {
+        std::cerr << "failed to open file for type " << certType
+                  << " ERROR=" << errno << "\n";
+        return PLDM_ERROR;
+    }
+    certMap.emplace(certType, std::tuple(fileFd, length));
+    return PLDM_SUCCESS;
+}
+
+} // namespace responder
+} // namespace pldm