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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 <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 <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(void *ctx)

{

        struct md5_ctx *mctx = ctx;

        mctx->hash[0] = 0x67452301;

        mctx->hash[1] = 0xefcdab89;

        mctx->hash[2] = 0x98badcfe;

        mctx->hash[3] = 0x10325476;

        mctx->byte_count = 0;

}

static void md5_update(void *ctx, const u8 *data, unsigned int len)

{

        struct md5_ctx *mctx = ctx;

        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(void *ctx, u8 *out)

{

        struct md5_ctx *mctx = ctx;

        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");