sha1.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
 *
 * SHA-1 algorithm
 *
 */

#include <stdint.h>
#include <string.h>
#include <byteswap.h>
#include <assert.h>
#include <ipxe/rotate.h>
#include <ipxe/crypto.h>
#include <ipxe/sha1.h>

/** SHA-1 variables */
struct sha1_variables {
        /* This layout matches that of struct sha1_digest_data,
         * allowing for efficient endianness-conversion,
         */
        uint32_t a;
        uint32_t b;
        uint32_t c;
        uint32_t d;
        uint32_t e;
        uint32_t w[80];
} __attribute__ (( packed ));

/**
 * f(a,b,c,d) for steps 0 to 19
 *
 * @v v         SHA-1 variables
 * @ret f       f(a,b,c,d)
 */
static uint32_t sha1_f_0_19 ( struct sha1_variables *v ) {
        return ( ( v->b & v->c ) | ( (~v->b) & v->d ) );
}

/**
 * f(a,b,c,d) for steps 20 to 39 and 60 to 79
 *
 * @v v         SHA-1 variables
 * @ret f       f(a,b,c,d)
 */
static uint32_t sha1_f_20_39_60_79 ( struct sha1_variables *v ) {
        return ( v->b ^ v->c ^ v->d );
}

/**
 * f(a,b,c,d) for steps 40 to 59
 *
 * @v v         SHA-1 variables
 * @ret f       f(a,b,c,d)
 */
static uint32_t sha1_f_40_59 ( struct sha1_variables *v ) {
        return ( ( v->b & v->c ) | ( v->b & v->d ) | ( v->c & v->d ) );
}

/** An SHA-1 step function */
struct sha1_step {
        /**
         * Calculate f(a,b,c,d)
         *
         * @v v         SHA-1 variables
         * @ret f       f(a,b,c,d)
         */
        uint32_t ( * f ) ( struct sha1_variables *v );
        /** Constant k */
        uint32_t k;
};

/** SHA-1 steps */
static struct sha1_step sha1_steps[4] = {
        /** 0 to 19 */
        { .f = sha1_f_0_19,             .k = 0x5a827999 },
        /** 20 to 39 */
        { .f = sha1_f_20_39_60_79,      .k = 0x6ed9eba1 },
        /** 40 to 59 */
        { .f = sha1_f_40_59,            .k = 0x8f1bbcdc },
        /** 60 to 79 */
        { .f = sha1_f_20_39_60_79,      .k = 0xca62c1d6 },
};

/**
 * Initialise SHA-1 algorithm
 *
 * @v ctx               SHA-1 context
 */
static void sha1_init ( void *ctx ) {
        struct sha1_context *context = ctx;

        context->ddd.dd.digest.h[0] = cpu_to_be32 ( 0x67452301 );
        context->ddd.dd.digest.h[1] = cpu_to_be32 ( 0xefcdab89 );
        context->ddd.dd.digest.h[2] = cpu_to_be32 ( 0x98badcfe );
        context->ddd.dd.digest.h[3] = cpu_to_be32 ( 0x10325476 );
        context->ddd.dd.digest.h[4] = cpu_to_be32 ( 0xc3d2e1f0 );
        context->len = 0;
}

/**
 * Calculate SHA-1 digest of accumulated data
 *
 * @v context           SHA-1 context
 */
static void sha1_digest ( struct sha1_context *context ) {
        union {
                union sha1_digest_data_dwords ddd;
                struct sha1_variables v;
        } u;
        uint32_t *a = &u.v.a;
        uint32_t *b = &u.v.b;
        uint32_t *c = &u.v.c;
        uint32_t *d = &u.v.d;
        uint32_t *e = &u.v.e;
        uint32_t *w = u.v.w;
        uint32_t f;
        uint32_t k;
        uint32_t temp;
        struct sha1_step *step;
        unsigned int i;

        /* Sanity checks */
        assert ( ( context->len % sizeof ( context->ddd.dd.data ) ) == 0 );
        build_assert ( &u.ddd.dd.digest.h[0] == a );
        build_assert ( &u.ddd.dd.digest.h[1] == b );
        build_assert ( &u.ddd.dd.digest.h[2] == c );
        build_assert ( &u.ddd.dd.digest.h[3] == d );
        build_assert ( &u.ddd.dd.digest.h[4] == e );
        build_assert ( &u.ddd.dd.data.dword[0] == w );

        DBGC ( context, "SHA1 digesting:\n" );
        DBGC_HDA ( context, 0, &context->ddd.dd.digest,
                   sizeof ( context->ddd.dd.digest ) );
        DBGC_HDA ( context, context->len, &context->ddd.dd.data,
                   sizeof ( context->ddd.dd.data ) );

        /* Convert h[0..4] to host-endian, and initialise a, b, c, d,
         * e, and w[0..15]
         */
        for ( i = 0 ; i < ( sizeof ( u.ddd.dword ) /
                            sizeof ( u.ddd.dword[0] ) ) ; i++ ) {
                be32_to_cpus ( &context->ddd.dword[i] );
                u.ddd.dword[i] = context->ddd.dword[i];
        }

        /* Initialise w[16..79] */
        for ( i = 16 ; i < 80 ; i++ )
                w[i] = rol32 ( ( w[i-3] ^ w[i-8] ^ w[i-14] ^ w[i-16] ), 1 );

        /* Main loop */
        for ( i = 0 ; i < 80 ; i++ ) {
                step = &sha1_steps[ i / 20 ];
                f = step->f ( &u.v );
                k = step->k;
                temp = ( rol32 ( *a, 5 ) + f + *e + k + w[i] );
                *e = *d;
                *d = *c;
                *c = rol32 ( *b, 30 );
                *b = *a;
                *a = temp;
                DBGC2 ( context, "%2d : %08x %08x %08x %08x %08x\n",
                        i, *a, *b, *c, *d, *e );
        }

        /* Add chunk to hash and convert back to big-endian */
        for ( i = 0 ; i < 5 ; i++ ) {
                context->ddd.dd.digest.h[i] =
                        cpu_to_be32 ( context->ddd.dd.digest.h[i] +
                                      u.ddd.dd.digest.h[i] );
        }

        DBGC ( context, "SHA1 digested:\n" );
        DBGC_HDA ( context, 0, &context->ddd.dd.digest,
                   sizeof ( context->ddd.dd.digest ) );
}

/**
 * Accumulate data with SHA-1 algorithm
 *
 * @v ctx               SHA-1 context
 * @v data              Data
 * @v len               Length of data
 */
static void sha1_update ( void *ctx, const void *data, size_t len ) {
        struct sha1_context *context = ctx;
        const uint8_t *byte = data;
        size_t offset;

        /* Accumulate data a byte at a time, performing the digest
         * whenever we fill the data buffer
         */
        while ( len-- ) {
                offset = ( context->len % sizeof ( context->ddd.dd.data ) );
                context->ddd.dd.data.byte[offset] = *(byte++);
                context->len++;
                if ( ( context->len % sizeof ( context->ddd.dd.data ) ) == 0 )
                        sha1_digest ( context );
        }
}

/**
 * Generate SHA-1 digest
 *
 * @v ctx               SHA-1 context
 * @v out               Output buffer
 */
static void sha1_final ( void *ctx, void *out ) {
        struct sha1_context *context = ctx;
        uint64_t len_bits;
        uint8_t pad;

        /* Record length before pre-processing */
        len_bits = cpu_to_be64 ( ( ( uint64_t ) context->len ) * 8 );

        /* Pad with a single "1" bit followed by as many "0" bits as required */
        pad = 0x80;
        do {
                sha1_update ( ctx, &pad, sizeof ( pad ) );
                pad = 0x00;
        } while ( ( context->len % sizeof ( context->ddd.dd.data ) ) !=
                  offsetof ( typeof ( context->ddd.dd.data ), final.len ) );

        /* Append length (in bits) */
        sha1_update ( ctx, &len_bits, sizeof ( len_bits ) );
        assert ( ( context->len % sizeof ( context->ddd.dd.data ) ) == 0 );

        /* Copy out final digest */
        memcpy ( out, &context->ddd.dd.digest,
                 sizeof ( context->ddd.dd.digest ) );
}

/** SHA-1 algorithm */
struct digest_algorithm sha1_algorithm = {
        .name           = "sha1",
        .ctxsize        = sizeof ( struct sha1_context ),
        .blocksize      = sizeof ( union sha1_block ),
        .digestsize     = sizeof ( struct sha1_digest ),
        .init           = sha1_init,
        .update         = sha1_update,
        .final          = sha1_final,
};