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md5.c

/* 
 * Cryptographic API.
 *
 * MD5 Message Digest Algorithm (RFC1321).
 *
 * Derived from cryptoapi implementation, originally based on the
 * public domain implementation written by Colin Plumb in 1993.
 *
 * Copyright (c) Cryptoapi developers.
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * 
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option) 
 * any later version.
 *
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/crypto.h>
#include <linux/types.h>
#include <asm/byteorder.h>

#define MD5_DIGEST_SIZE       16
#define MD5_HMAC_BLOCK_SIZE   64
#define MD5_BLOCK_WORDS       16
#define MD5_HASH_WORDS        4

#define F1(x, y, z)     (z ^ (x & (y ^ z)))
#define F2(x, y, z)     F1(z, x, y)
#define F3(x, y, z)     (x ^ y ^ z)
#define F4(x, y, z)     (y ^ (x | ~z))

#define MD5STEP(f, w, x, y, z, in, s) \
      (w += f(x, y, z) + in, w = (w<<s | w>>(32-s)) + x)

struct md5_ctx {
      u32 hash[MD5_HASH_WORDS];
      u32 block[MD5_BLOCK_WORDS];
      u64 byte_count;
};

static void md5_transform(u32 *hash, u32 const *in)
{
      u32 a, b, c, d;

      a = hash[0];
      b = hash[1];
      c = hash[2];
      d = hash[3];

      MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
      MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
      MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
      MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
      MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
      MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
      MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
      MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
      MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
      MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
      MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
      MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
      MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
      MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
      MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
      MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

      MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
      MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
      MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
      MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
      MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
      MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
      MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
      MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
      MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
      MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
      MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
      MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
      MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
      MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
      MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
      MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

      MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
      MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
      MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
      MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
      MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
      MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
      MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
      MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
      MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
      MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
      MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
      MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
      MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
      MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
      MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
      MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

      MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
      MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
      MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
      MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
      MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
      MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
      MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
      MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
      MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
      MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
      MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
      MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
      MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
      MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
      MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
      MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

      hash[0] += a;
      hash[1] += b;
      hash[2] += c;
      hash[3] += d;
}

/* XXX: this stuff can be optimized */
static inline void le32_to_cpu_array(u32 *buf, unsigned int words)
{
      while (words--) {
            __le32_to_cpus(buf);
            buf++;
      }
}

static inline void cpu_to_le32_array(u32 *buf, unsigned int words)
{
      while (words--) {
            __cpu_to_le32s(buf);
            buf++;
      }
}

static inline void md5_transform_helper(struct md5_ctx *ctx)
{
      le32_to_cpu_array(ctx->block, sizeof(ctx->block) / sizeof(u32));
      md5_transform(ctx->hash, ctx->block);
}

static void md5_init(struct crypto_tfm *tfm)
{
      struct md5_ctx *mctx = crypto_tfm_ctx(tfm);

      mctx->hash[0] = 0x67452301;
      mctx->hash[1] = 0xefcdab89;
      mctx->hash[2] = 0x98badcfe;
      mctx->hash[3] = 0x10325476;
      mctx->byte_count = 0;
}

static void md5_update(struct crypto_tfm *tfm, const u8 *data, unsigned int len)
{
      struct md5_ctx *mctx = crypto_tfm_ctx(tfm);
      const u32 avail = sizeof(mctx->block) - (mctx->byte_count & 0x3f);

      mctx->byte_count += len;

      if (avail > len) {
            memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
                   data, len);
            return;
      }

      memcpy((char *)mctx->block + (sizeof(mctx->block) - avail),
             data, avail);

      md5_transform_helper(mctx);
      data += avail;
      len -= avail;

      while (len >= sizeof(mctx->block)) {
            memcpy(mctx->block, data, sizeof(mctx->block));
            md5_transform_helper(mctx);
            data += sizeof(mctx->block);
            len -= sizeof(mctx->block);
      }

      memcpy(mctx->block, data, len);
}

static void md5_final(struct crypto_tfm *tfm, u8 *out)
{
      struct md5_ctx *mctx = crypto_tfm_ctx(tfm);
      const unsigned int offset = mctx->byte_count & 0x3f;
      char *p = (char *)mctx->block + offset;
      int padding = 56 - (offset + 1);

      *p++ = 0x80;
      if (padding < 0) {
            memset(p, 0x00, padding + sizeof (u64));
            md5_transform_helper(mctx);
            p = (char *)mctx->block;
            padding = 56;
      }

      memset(p, 0, padding);
      mctx->block[14] = mctx->byte_count << 3;
      mctx->block[15] = mctx->byte_count >> 29;
      le32_to_cpu_array(mctx->block, (sizeof(mctx->block) -
                        sizeof(u64)) / sizeof(u32));
      md5_transform(mctx->hash, mctx->block);
      cpu_to_le32_array(mctx->hash, sizeof(mctx->hash) / sizeof(u32));
      memcpy(out, mctx->hash, sizeof(mctx->hash));
      memset(mctx, 0, sizeof(*mctx));
}

static struct crypto_alg alg = {
      .cra_name   =     "md5",
      .cra_flags  =     CRYPTO_ALG_TYPE_DIGEST,
      .cra_blocksize    =     MD5_HMAC_BLOCK_SIZE,
      .cra_ctxsize      =     sizeof(struct md5_ctx),
      .cra_module =     THIS_MODULE,
      .cra_list   =     LIST_HEAD_INIT(alg.cra_list),
      .cra_u            =     { .digest = {
      .dia_digestsize   =     MD5_DIGEST_SIZE,
      .dia_init         =     md5_init,
      .dia_update       =     md5_update,
      .dia_final        =     md5_final } }
};

static int __init init(void)
{
      return crypto_register_alg(&alg);
}

static void __exit fini(void)
{
      crypto_unregister_alg(&alg);
}

module_init(init);
module_exit(fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MD5 Message Digest Algorithm");

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