12.3.3.2 SHA-256 API

The SHA-256 API can be used to hash variable lengths of input data.

The SHA-256 structure to define is called SHA56_CTX:

/*
*Context structure used by the crya_sha256_init, crya_sha256_update andcrya_sha256_final functions.
*/
typedef struct {
    /* Digest result of SHA256 */
    uint32_t digest[8];
    /* Length of the message */
    uint64_t length;
    /* Holds the size of the remaining part of data */
    uint32_t remain_size;
    /* Buffer of remaining part of data (512 bits data block) */
    uint8_t remain_ram[64];
    /* RAM buffer of 256 bytes used by crya_sha_process */
    uint32_t process_buf[64];
} SHA256_CTX;

The SHA-256 Init function entry point is located at the Boot ROM address 0x02006810:

/**
*\brief Type definition for SHA256 initialization function.
*
*\param context[In/Out]: A pointer to a SHA256_CTX structure.
*/
typedef void (*crya_sha256_init_t) (SHA256_CTX *context);
#define crya_sha_init ((crya_sha256_init_t) (0x02006810 | 0x1))

The SHA-256 Update function entry point is located at the Boot ROM address 0x02006814:

/**
*\brief Type definition for SHA256 update function.
*
*\param context[In/Out]: A pointer to a SHA256_CTX structure.
*\param data[In]:A pointer to a byte-aligned message
*\param length[In]:Size in bytes of the message
*/
typedef void (*crya_sha256_update_t) (SHA256_CTX *context, const unsigned char *data, size_t length);
#define crya_sha_update ((crya_sha256_update_t) (0x02006814 | 0x1))

The SHA-256 Final function entry point is located at the Boot ROM address 0x02006818:

/**
*\brief Type definition for SHA256 final function.
*
*\param context[In/Out]: A pointer to a SHA256_CTX structure.
*\param output[Out]:A pointer to the final SHA256 result.
*/
typedef void (*crya_sha256_final_t) (SHA256_CTX *context, unsigned char output[32]);
#define crya_sha256_final ((crya_sha256_final_t) (0x02006818 | 0x1))

Code example of using CRYA SHA-256 API:

void sha256_hash(SHA256_CTX *ctx, const uint8_t *message, uint32_t length, unsigned char digest[32])
{
    crya_sha256_init(ctx);
    crya_sha256_update(ctx, message, length);
    crya_sha256_final(ctx, digest);
}