source: bootcd/isolinux/syslinux-6.03/gpxe/src/crypto/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.
 *
 * Reduced object size by around 50% compared to the original Linux
 * version for use in Etherboot by Michael Brown.
 *
 * Copyright (c) Cryptoapi developers.
 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
 * Copyright (c) 2006 Michael Brown <mbrown@fensystems.co.uk>
 * 
 * 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.
 *
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdint.h>
#include <string.h>
#include <byteswap.h>
#include <gpxe/crypto.h>
#include <gpxe/md5.h>

struct md5_step {
        u32 ( * f ) ( u32 b, u32 c, u32 d );
        u8 coefficient;
        u8 constant;
};

static u32 f1(u32 b, u32 c, u32 d)
{
        return ( d ^ ( b & ( c ^ d ) ) );
}

static u32 f2(u32 b, u32 c, u32 d)
{
        return ( c ^ ( d & ( b ^ c ) ) );
}

static u32 f3(u32 b, u32 c, u32 d)
{
        return ( b ^ c ^ d );
}

static u32 f4(u32 b, u32 c, u32 d)
{
        return ( c ^ ( b | ~d ) );
}

static struct md5_step md5_steps[4] = {
        {
                .f = f1,
                .coefficient = 1,
                .constant = 0,
        },
        {
                .f = f2,
                .coefficient = 5,
                .constant = 1,
        },
        {
                .f = f3,
                .coefficient = 3,
                .constant = 5,
        },
        {
                .f = f4,
                .coefficient = 7,
                .constant = 0,
        }
};

static const u8 r[64] = {
        7,12,17,22,7,12,17,22,7,12,17,22,7,12,17,22,
        5,9,14,20,5,9,14,20,5,9,14,20,5,9,14,20,
        4,11,16,23,4,11,16,23,4,11,16,23,4,11,16,23,
        6,10,15,21,6,10,15,21,6,10,15,21,6,10,15,21
};

static const u32 k[64] = {
        0xd76aa478UL, 0xe8c7b756UL, 0x242070dbUL, 0xc1bdceeeUL,
        0xf57c0fafUL, 0x4787c62aUL, 0xa8304613UL, 0xfd469501UL,
        0x698098d8UL, 0x8b44f7afUL, 0xffff5bb1UL, 0x895cd7beUL,
        0x6b901122UL, 0xfd987193UL, 0xa679438eUL, 0x49b40821UL,
        0xf61e2562UL, 0xc040b340UL, 0x265e5a51UL, 0xe9b6c7aaUL,
        0xd62f105dUL, 0x02441453UL, 0xd8a1e681UL, 0xe7d3fbc8UL,
        0x21e1cde6UL, 0xc33707d6UL, 0xf4d50d87UL, 0x455a14edUL,
        0xa9e3e905UL, 0xfcefa3f8UL, 0x676f02d9UL, 0x8d2a4c8aUL,
        0xfffa3942UL, 0x8771f681UL, 0x6d9d6122UL, 0xfde5380cUL,
        0xa4beea44UL, 0x4bdecfa9UL, 0xf6bb4b60UL, 0xbebfbc70UL,
        0x289b7ec6UL, 0xeaa127faUL, 0xd4ef3085UL, 0x04881d05UL,
        0xd9d4d039UL, 0xe6db99e5UL, 0x1fa27cf8UL, 0xc4ac5665UL,
        0xf4292244UL, 0x432aff97UL, 0xab9423a7UL, 0xfc93a039UL,
        0x655b59c3UL, 0x8f0ccc92UL, 0xffeff47dUL, 0x85845dd1UL,
        0x6fa87e4fUL, 0xfe2ce6e0UL, 0xa3014314UL, 0x4e0811a1UL,
        0xf7537e82UL, 0xbd3af235UL, 0x2ad7d2bbUL, 0xeb86d391UL,
};

static void md5_transform(u32 *hash, const u32 *in)
{
        u32 a, b, c, d, f, g, temp;
        int i;
        struct md5_step *step;

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

        for ( i = 0 ; i < 64 ; i++ ) {
                step = &md5_steps[i >> 4];
                f = step->f ( b, c, d );
                g = ( ( i * step->coefficient + step->constant ) & 0xf );
                temp = d;
                d = c;
                c = b;
                a += ( f + k[i] + in[g] );
                a = ( ( a << r[i] ) | ( a >> ( 32-r[i] ) ) );
                b += a;
                a = temp;
        }

        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 *context)
{
        struct md5_ctx *mctx = context;

        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 *context, const void *data, size_t len)
{
        struct md5_ctx *mctx = context;
        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 *context, void *out)
{
        struct md5_ctx *mctx = context;
        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));
}

struct digest_algorithm md5_algorithm = {
        .name           = "md5",
        .ctxsize        = MD5_CTX_SIZE,
        .blocksize      = ( MD5_BLOCK_WORDS * 4 ),
        .digestsize     = MD5_DIGEST_SIZE,
        .init           = md5_init,
        .update         = md5_update,
        .final          = md5_final,
};