crypt_algo.hpp

#pragma once

#include <openssl/sha.h>
#include <array>
#include <vector>

namespace cipher
{

namespace crypt
{

using buffer = std::vector<uint8_t>;
using key = std::array<uint8_t, SHA_DIGEST_LENGTH>;

/**
 * @enum Confidentiality Algorithms
 *
 * The Confidentiality Algorithm Number specifies the encryption/decryption
 * algorithm field that is used for encrypted payload data under the session.
 * The ‘encrypted’ bit in the payload type field being set identifies packets
 * with payloads that include data that is encrypted per this specification.
 * When payload data is encrypted, there may be additional “Confidentiality
 * Header” and/or “Confidentiality Trailer” fields that are included within the
 * payload. The size and definition of those fields is specific to the
 * particular confidentiality algorithm.
 */
enum class Algorithms : uint8_t
{
    NONE,               /**< No encryption (mandatory option) */
    AES_CBC_128,        /**< AES-CBC-128 Algorithm (mandatory option) */
    xRC4_128,           /**< xRC4-128 Algorithm (optional option) */
    xRC4_40,            /**< xRC4-40 Algorithm (optional option) */
};

/**
 * @class Interface
 *
 * Interface is the base class for the Confidentiality Algorithms.
 */
class Interface
{
    public:
        /**
         * @brief Constructor for Interface
         *
         * @param[in] - Session Integrity key to generate K2
         * @param[in] - Additional keying material to generate K2
         */
        explicit Interface(const buffer& sik, const key& addKey);

        Interface() = delete;
        virtual ~Interface() = default;
        Interface(const Interface&) = default;
        Interface& operator=(const Interface&) = default;
        Interface(Interface&&) = default;
        Interface& operator=(Interface&&) = default;

        /**
         * @brief Decrypt the incoming payload
         *
         * @param[in] packet - Incoming IPMI packet
         * @param[in] sessHeaderLen - Length of the IPMI Session Header
         * @param[in] payloadLen - Length of the encrypted IPMI payload
         *
         * @return decrypted payload if the operation is successful
         */
        virtual buffer decryptPayload(
                const buffer& packet,
                const size_t sessHeaderLen,
                const size_t payloadLen) const = 0;

        /**
         * @brief Encrypt the outgoing payload
         *
         * @param[in] payload - plain payload for the outgoing IPMI packet
         *
         * @return encrypted payload if the operation is successful
         *
         */
        virtual buffer encryptPayload(buffer& payload) const = 0;

    protected:

        /** @brief K2 is the key used for encrypting data */
        key k2;
};

/**
 * @class AlgoAES128
 *
 * @brief Implementation of the AES-CBC-128 Confidentiality algorithm
 *
 * AES-128 uses a 128-bit Cipher Key. The Cipher Key is the first 128-bits of
 * key “K2”.Once the Cipher Key has been generated it is used to encrypt
 * the payload data. The payload data is padded to make it an integral numbers
 * of blocks in length (a block is 16 bytes for AES). The payload is then
 * encrypted one block at a time from the lowest data offset to the highest
 * using Cipher_Key as specified in AES.
 */
class AlgoAES128 final : public Interface
{
    public:
        static constexpr size_t AESCBC128ConfHeader = 16;
        static constexpr size_t AESCBC128BlockSize = 16;

        /**
         * RSP needs more keying material than can be provided by session
         * integrity key alone. As a result all keying material for the RSP
         * confidentiality algorithms will be generated by processing a
         * pre-defined set of constants using HMAC per [RFC2104], keyed by SIK.
         * These constants are constructed using a hexadecimal octet value
         * repeated up to the HMAC block size in length starting with the
         * constant 01h. This mechanism can be used to derive up to 255
         * HMAC-block-length pieces of keying material from a single SIK.For the
         * mandatory confidentiality algorithm AES-CBC-128, processing the
         * following constant will generate the required amount of keying
         * material.
         */
        static constexpr key const2 = { 0x02, 0x02, 0x02, 0x02, 0x02,
                                        0x02, 0x02, 0x02, 0x02, 0x02,
                                        0x02, 0x02, 0x02, 0x02, 0x02,
                                        0x02, 0x02, 0x02, 0x02, 0x02
                                       };

        /**
         * If confidentiality bytes are present, the value of the first byte is
         * one (01h). and all subsequent bytes shall have a monotonically
         * increasing value (e.g., 02h, 03h, 04h, etc). The receiver, as an
         * additional check for proper decryption, shall check the value of each
         * byte of Confidentiality Pad. For AES algorithm, the pad bytes will
         * range from 0 to 15 bytes. This predefined array would help in
         * doing the additional check.
         */
        static constexpr std::array<uint8_t, AESCBC128BlockSize -1>
                confPadBytes =
                { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
                  0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F };

        /**
         * @brief Constructor for AlgoAES128
         *
         * @param[in] - Session Integrity key
         */
        explicit AlgoAES128(const buffer& sik) : Interface(sik, const2) {}

        AlgoAES128() = delete;
        ~AlgoAES128() = default;
        AlgoAES128(const AlgoAES128&) = default;
        AlgoAES128& operator=(const AlgoAES128&) = default;
        AlgoAES128(AlgoAES128&&) = default;
        AlgoAES128& operator=(AlgoAES128&&) = default;

        /**
         * @brief Decrypt the incoming payload
         *
         * @param[in] packet - Incoming IPMI packet
         * @param[in] sessHeaderLen - Length of the IPMI Session Header
         * @param[in] payloadLen - Length of the encrypted IPMI payload
         *
         * @return decrypted payload if the operation is successful
         */
        buffer decryptPayload(
                const buffer& packet,
                const size_t sessHeaderLen,
                const size_t payloadLen) const override;

        /**
         * @brief Encrypt the outgoing payload
         *
         * @param[in] payload - plain payload for the outgoing IPMI packet
         *
         * @return encrypted payload if the operation is successful
         *
         */
        buffer encryptPayload(buffer& payload) const override;

    private:

        /**
         * @brief Decrypt the passed data
         *
         * @param[in] iv - Initialization vector
         * @param[in] input - Pointer to input data
         * @param[in] inputLen - Length of input data
         *
         * @return decrypted data if the operation is successful
         */
        buffer decryptData(const uint8_t* iv,
                           const uint8_t* input,
                           const int inputLen) const;

        /**
         * @brief Encrypt the passed data
         *
         * @param[in] input - Pointer to input data
         * @param[in] inputLen - Length of input data
         *
         * @return encrypted data if the operation is successful
         */
        buffer encryptData(const uint8_t* input,
                           const int inputLen) const;
};

}// namespace crypt

}// namespace cipher