md5.c

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/* 
 * 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 <[email protected]>
 * 
 * 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 <crypto/internal/hash.h>
#include <crypto/md5.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/cryptohash.h>
#include <asm/byteorder.h>

/* 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_state *ctx)
{
    le32_to_cpu_array(ctx->block, sizeof(ctx->block) / sizeof(u32));
    md5_transform(ctx->hash, ctx->block);
}

static int md5_init(struct shash_desc *desc)
{
    struct md5_state *mctx = shash_desc_ctx(desc);

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

    return 0;
}

static int md5_update(struct shash_desc *desc, const u8 *data, unsigned int len)
{
    struct md5_state *mctx = shash_desc_ctx(desc);
    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 0;
    }

    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);

    return 0;
}

static int md5_final(struct shash_desc *desc, u8 *out)
{
    struct md5_state *mctx = shash_desc_ctx(desc);
    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));

    return 0;
}

static int md5_export(struct shash_desc *desc, void *out)
{
    struct md5_state *ctx = shash_desc_ctx(desc);

    memcpy(out, ctx, sizeof(*ctx));
    return 0;
}

static int md5_import(struct shash_desc *desc, const void *in)
{
    struct md5_state *ctx = shash_desc_ctx(desc);

    memcpy(ctx, in, sizeof(*ctx));
    return 0;
}

static struct shash_alg alg = {
    .digestsize =   MD5_DIGEST_SIZE,
    .init       =   md5_init,
    .update     =   md5_update,
    .final      =   md5_final,
    .export     =   md5_export,
    .import     =   md5_import,
    .descsize   =   sizeof(struct md5_state),
    .statesize  =   sizeof(struct md5_state),
    .base       =   {
        .cra_name   =   "md5",
        .cra_flags  =   CRYPTO_ALG_TYPE_SHASH,
        .cra_blocksize  =   MD5_HMAC_BLOCK_SIZE,
        .cra_module =   THIS_MODULE,
    }
};

static int __init md5_mod_init(void)
{
    return crypto_register_shash(&alg);
}

static void __exit md5_mod_fini(void)
{
    crypto_unregister_shash(&alg);
}

module_init(md5_mod_init);
module_exit(md5_mod_fini);

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