md5.c

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/*
 * Copyright (C) 2012 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 any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */
 
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
FILE_SECBOOT ( PERMITTED );
 
/** @file
 *
 * MD5 algorithm
 *
 */
 
#include <stdint.h>
#include <assert.h>
#include <ipxe/rotate.h>
#include <ipxe/crypto.h>
#include <ipxe/md5.h>
 
/** MD5 variables */
struct md5_variables {
        /* This layout matches that of struct md5_digest_data */
        uint32_t a;
        uint32_t b;
        uint32_t c;
        uint32_t d;
        uint32_t w[16];
} __attribute__ (( packed ));
 
/** MD5 constants */
static const uint32_t k[64] = {
        0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787c62a,
        0xa8304613, 0xfd469501, 0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
        0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821, 0xf61e2562, 0xc040b340,
        0x265e5a51, 0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
        0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905, 0xfcefa3f8,
        0x676f02d9, 0x8d2a4c8a, 0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
        0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70, 0x289b7ec6, 0xeaa127fa,
        0xd4ef3085, 0x04881d05, 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
        0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92,
        0xffeff47d, 0x85845dd1, 0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
        0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
};
 
/** MD5 shift amounts */
static const uint8_t r[4][4] = {
        {  7, 12, 17, 22 },
        {  5,  9, 14, 20 },
        {  4, 11, 16, 23 },
        {  6, 10, 15, 21 },
};
 
/**
 * f(b,c,d) for steps 0 to 15
 *
 * @v v         MD5 variables
 * @ret f       f(b,c,d)
 */
static uint32_t md5_f_0_15 ( struct md5_variables *v ) {
        return ( v->d ^ ( v->b & ( v->c ^ v->d ) ) );
}
 
/**
 * f(b,c,d) for steps 16 to 31
 *
 * @v v         MD5 variables
 * @ret f       f(b,c,d)
 */
static uint32_t md5_f_16_31 ( struct md5_variables *v ) {
        return ( v->c ^ ( v->d & ( v->b ^ v->c ) ) );
}
 
/**
 * f(b,c,d) for steps 32 to 47
 *
 * @v v         MD5 variables
 * @ret f       f(b,c,d)
 */
static uint32_t md5_f_32_47 ( struct md5_variables *v ) {
        return ( v->b ^ v->c ^ v->d );
}
 
/**
 * f(b,c,d) for steps 48 to 63
 *
 * @v v         MD5 variables
 * @ret f       f(b,c,d)
 */
static uint32_t md5_f_48_63 ( struct md5_variables *v ) {
        return ( v->c ^ ( v->b | (~v->d) ) );
}
 
/** An MD5 step function */
struct md5_step {
        /**
         * Calculate f(b,c,d)
         *
         * @v v         MD5 variables
         * @ret f       f(b,c,d)
         */
        uint32_t ( * f ) ( struct md5_variables *v );
        /** Coefficient of i in g=ni+m */
        uint8_t coefficient;
        /** Constant term in g=ni+m */
        uint8_t constant;
};
 
/** MD5 steps */
static const struct md5_step md5_steps[4] = {
        /** 0 to 15 */
        { .f = md5_f_0_15,      .coefficient = 1,       .constant = 0 },
        /** 16 to 31 */
        { .f = md5_f_16_31,     .coefficient = 5,       .constant = 1 },
        /** 32 to 47 */
        { .f = md5_f_32_47,     .coefficient = 3,       .constant = 5 },
        /** 48 to 63 */
        { .f = md5_f_48_63,     .coefficient = 7,       .constant = 0 },
};
 
/** MD5 initial digest values */
static const struct md5_digest md5_init = {
        .h = { 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476 }
};
 
/**
 * Calculate MD5 digest of accumulated data
 *
 * @v dd                Digest and data block
 * @v digest            Copy of current digest value
 */
static void md5_compress ( struct md5_digest_data *dd,
                           const struct md5_digest *digest ) {
        union {
                struct md5_digest_data dd;
                struct md5_variables v;
        } *u = container_of ( dd, typeof ( *u ), dd );
        struct md5_variables *v = &u->v;
        const struct md5_step *step;
        uint32_t *a = &v->a;
        uint32_t *b = &v->b;
        uint32_t *c = &v->c;
        uint32_t *d = &v->d;
        uint32_t *w = v->w;
        uint32_t f;
        uint32_t g;
        uint32_t temp;
        unsigned int round;
        unsigned int i;
 
        /* Sanity checks */
        build_assert ( &u->dd.digest.h[0] == a );
        build_assert ( &u->dd.digest.h[1] == b );
        build_assert ( &u->dd.digest.h[2] == c );
        build_assert ( &u->dd.digest.h[3] == d );
        build_assert ( &u->dd.data.dword[0] == w );
        build_assert ( sizeof ( u->dd ) == sizeof ( u->v ) );
 
        /* Main loop */
        for ( i = 0 ; i < 64 ; i++ ) {
                round = ( i / 16 );
                step = &md5_steps[round];
                f = step->f ( v );
                g = ( ( ( step->coefficient * i ) + step->constant ) % 16 );
                temp = *d;
                *d = *c;
                *c = *b;
                *b = ( *b + rol32 ( ( *a + f + k[i] + w[g] ),
                                    r[round][ i % 4 ] ) );
                *a = temp;
                DBGC2 ( &md5_algorithm, "%2d : %08x %08x %08x %08x\n",
                        i, *a, *b, *c, *d );
        }
 
        /* Add chunk to hash */
        for ( i = 0 ; i < 4 ; i++ )
                dd->digest.h[i] += digest->h[i];
}
 
/** MD5 algorithm */
MDHASH_ALGORITHM ( md5, md5_algorithm, md5_compress, __LITTLE_ENDIAN,
                   struct md5_digest_data, md5_init, MD5_DIGEST_SIZE );