/**************************** usha.c ****************************/
/******************** See RFC 4634 for details ******************/
/*
 *  Description:
 *     This file implements a unified interface to the SHA algorithms.
 */

#include "sha.h"

/*
 *  USHAReset
 *
 *  Description:
 *      This function will initialize the SHA Context in preparation
 *      for computing a new SHA message digest.
 *
 *  Parameters:
 *      context: [in/out]
 *          The context to reset.
 *      whichSha: [in]
 *          Selects which SHA reset to call
 *
 *  Returns:
 *      sha Error Code.
 *
 */
int USHAReset(USHAContext *ctx, enum SHAversion whichSha)
{
  if (ctx) {
    ctx->whichSha = whichSha;
    switch (whichSha) {
      case CCSHA1:   return SHA1Reset((SHA1Context*)&ctx->ctx);
      case CCSHA224: return SHA224Reset((SHA224Context*)&ctx->ctx);
      case CCSHA256: return SHA256Reset((SHA256Context*)&ctx->ctx);
      case CCSHA384: return SHA384Reset((SHA384Context*)&ctx->ctx);
      case CCSHA512: return SHA512Reset((SHA512Context*)&ctx->ctx);
      default: return shaBadParam;
    }
  } else {
    return shaNull;
  }
}

/*
 *  USHAInput
 *
 *  Description:
 *      This function accepts an array of octets as the next portion
 *      of the message.
 *
 *  Parameters:
 *      context: [in/out]
 *          The SHA context to update
 *      message_array: [in]
 *          An array of characters representing the next portion of
 *          the message.
 *      length: [in]
 *          The length of the message in message_array
 *
 *  Returns:
 *      sha Error Code.
 *
 */
int USHAInput(USHAContext *ctx,
              const uint8_t *bytes, unsigned int bytecount)
{
  if (ctx) {
    switch (ctx->whichSha) {
      case CCSHA1:
        return SHA1Input((SHA1Context*)&ctx->ctx, bytes, bytecount);
      case CCSHA224:
        return SHA224Input((SHA224Context*)&ctx->ctx, bytes,
            bytecount);
      case CCSHA256:
        return SHA256Input((SHA256Context*)&ctx->ctx, bytes,
            bytecount);
      case CCSHA384:
        return SHA384Input((SHA384Context*)&ctx->ctx, bytes,
            bytecount);
      case CCSHA512:
        return SHA512Input((SHA512Context*)&ctx->ctx, bytes,
            bytecount);
      default: return shaBadParam;
    }
  } else {
    return shaNull;
  }
}

/*
 * USHAFinalBits
 *
 * Description:
 *   This function will add in any final bits of the message.
 *
 * Parameters:
 *   context: [in/out]
 *     The SHA context to update
 *   message_bits: [in]
 *     The final bits of the message, in the upper portion of the
 *     byte. (Use 0b###00000 instead of 0b00000### to input the
 *     three bits ###.)
 *   length: [in]
 *     The number of bits in message_bits, between 1 and 7.
 *
 * Returns:
 *   sha Error Code.
 */
int USHAFinalBits(USHAContext *ctx,
                  const uint8_t bits, unsigned int bitcount)
{
  if (ctx) {
    switch (ctx->whichSha) {
      case CCSHA1:
        return SHA1FinalBits((SHA1Context*)&ctx->ctx, bits, bitcount);
      case CCSHA224:
        return SHA224FinalBits((SHA224Context*)&ctx->ctx, bits,
            bitcount);
      case CCSHA256:
        return SHA256FinalBits((SHA256Context*)&ctx->ctx, bits,
            bitcount);
      case CCSHA384:
        return SHA384FinalBits((SHA384Context*)&ctx->ctx, bits,
            bitcount);
      case CCSHA512:
        return SHA512FinalBits((SHA512Context*)&ctx->ctx, bits,
            bitcount);
      default: return shaBadParam;
    }
  } else {
    return shaNull;
  }
}

/*
 * USHAResult
 *
 * Description:
 *   This function will return the 160-bit message digest into the
 *   Message_Digest array provided by the caller.
 *   NOTE: The first octet of hash is stored in the 0th element,
 *      the last octet of hash in the 19th element.
 *
 * Parameters:
 *   context: [in/out]
 *     The context to use to calculate the SHA-1 hash.
 *   Message_Digest: [out]
 *     Where the digest is returned.
 *
 * Returns:
 *   sha Error Code.
 *
 */
int USHAResult(USHAContext *ctx,
               uint8_t Message_Digest[USHAMaxHashSize])
{
  if (ctx) {
    switch (ctx->whichSha) {
      case CCSHA1:
        return SHA1Result((SHA1Context*)&ctx->ctx, Message_Digest);
      case CCSHA224:
        return SHA224Result((SHA224Context*)&ctx->ctx, Message_Digest);
      case CCSHA256:
        return SHA256Result((SHA256Context*)&ctx->ctx, Message_Digest);
      case CCSHA384:
        return SHA384Result((SHA384Context*)&ctx->ctx, Message_Digest);
      case CCSHA512:
        return SHA512Result((SHA512Context*)&ctx->ctx, Message_Digest);
      default: return shaBadParam;
    }
  } else {
    return shaNull;
  }
}

/*
 * USHABlockSize
 *
 * Description:
 *   This function will return the blocksize for the given SHA
 *   algorithm.
 *
 * Parameters:
 *   whichSha:
 *     which SHA algorithm to query
 *
 * Returns:
 *   block size
 *
 */
int USHABlockSize(enum SHAversion whichSha)
{
  switch (whichSha) {
    case CCSHA1:   return SHA1_Message_Block_Size;
    case CCSHA224: return SHA224_Message_Block_Size;
    case CCSHA256: return SHA256_Message_Block_Size;
    case CCSHA384: return SHA384_Message_Block_Size;
    default:
    case CCSHA512: return SHA512_Message_Block_Size;
  }
}

/*
 * USHAHashSize
 *
 * Description:
 *   This function will return the hashsize for the given SHA
 *   algorithm.
 *
 * Parameters:
 *   whichSha:
 *     which SHA algorithm to query
 *
 * Returns:
 *   hash size
 *
 */
int USHAHashSize(enum SHAversion whichSha)
{
  switch (whichSha) {
    case CCSHA1:   return SHA1HashSize;
    case CCSHA224: return SHA224HashSize;
    case CCSHA256: return SHA256HashSize;
    case CCSHA384: return SHA384HashSize;
    default:
    case CCSHA512: return SHA512HashSize;
  }
}

/*
 * USHAHashSizeBits
 *
 * Description:
 *   This function will return the hashsize for the given SHA
 *   algorithm, expressed in bits.
 *
 * Parameters:
 *   whichSha:
 *     which SHA algorithm to query
 *
 * Returns:
 *   hash size in bits
 *
 */
int USHAHashSizeBits(enum SHAversion whichSha)
{
  switch (whichSha) {
    case CCSHA1:   return SHA1HashSizeBits;
    case CCSHA224: return SHA224HashSizeBits;
    case CCSHA256: return SHA256HashSizeBits;
    case CCSHA384: return SHA384HashSizeBits;
    default:
    case CCSHA512: return SHA512HashSizeBits;
  }
}