sha256.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-256 algorithm
 *
 */

#include <stdint.h>
#include <string.h>
#include <byteswap.h>
#include <assert.h>
#include <ipxe/rotate.h>
#include <ipxe/crypto.h>
#include <ipxe/sha256.h>

/** SHA-256 variables */
struct sha256_variables {
        /* This layout matches that of struct sha256_digest_data,
         * allowing for efficient endianness-conversion,
         */
        uint32_t a;
        uint32_t b;
        uint32_t c;
        uint32_t d;
        uint32_t e;
        uint32_t f;
        uint32_t g;
        uint32_t h;
        uint32_t w[SHA256_ROUNDS];
} __attribute__ (( packed ));

/** SHA-256 constants */
static const uint32_t k[SHA256_ROUNDS] = {
        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
        0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
        0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
        0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
        0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
        0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
        0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
        0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
        0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
        0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
        0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
};

/** SHA-256 initial digest values */
static const struct sha256_digest sha256_init_digest = {
        .h = {
                cpu_to_be32 ( 0x6a09e667 ),
                cpu_to_be32 ( 0xbb67ae85 ),
                cpu_to_be32 ( 0x3c6ef372 ),
                cpu_to_be32 ( 0xa54ff53a ),
                cpu_to_be32 ( 0x510e527f ),
                cpu_to_be32 ( 0x9b05688c ),
                cpu_to_be32 ( 0x1f83d9ab ),
                cpu_to_be32 ( 0x5be0cd19 ),
        },
};

/**
 * Initialise SHA-256 family algorithm
 *
 * @v context           SHA-256 context
 * @v init              Initial digest values
 * @v digestsize        Digest size
 */
void sha256_family_init ( struct sha256_context *context,
                          const struct sha256_digest *init,
                          size_t digestsize ) {

        context->len = 0;
        context->digestsize = digestsize;
        memcpy ( &context->ddd.dd.digest, init,
                 sizeof ( context->ddd.dd.digest ) );
}

/**
 * Initialise SHA-256 algorithm
 *
 * @v ctx               SHA-256 context
 */
static void sha256_init ( void *ctx ) {
        struct sha256_context *context = ctx;

        sha256_family_init ( context, &sha256_init_digest,
                             sizeof ( struct sha256_digest ) );
}

/**
 * Calculate SHA-256 digest of accumulated data
 *
 * @v context           SHA-256 context
 */
static void sha256_digest ( struct sha256_context *context ) {
        union {
                union sha256_digest_data_dwords ddd;
                struct sha256_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 *f = &u.v.f;
        uint32_t *g = &u.v.g;
        uint32_t *h = &u.v.h;
        uint32_t *w = u.v.w;
        uint32_t s0;
        uint32_t s1;
        uint32_t maj;
        uint32_t t1;
        uint32_t t2;
        uint32_t ch;
        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.digest.h[5] == f );
        build_assert ( &u.ddd.dd.digest.h[6] == g );
        build_assert ( &u.ddd.dd.digest.h[7] == h );
        build_assert ( &u.ddd.dd.data.dword[0] == w );

        DBGC ( context, "SHA256 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..7] to host-endian, and initialise a, b, c, d,
         * e, f, g, h, 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..63] */
        for ( i = 16 ; i < SHA256_ROUNDS ; i++ ) {
                s0 = ( ror32 ( w[i-15], 7 ) ^ ror32 ( w[i-15], 18 ) ^
                       ( w[i-15] >> 3 ) );
                s1 = ( ror32 ( w[i-2], 17 ) ^ ror32 ( w[i-2], 19 ) ^
                       ( w[i-2] >> 10 ) );
                w[i] = ( w[i-16] + s0 + w[i-7] + s1 );
        }

        /* Main loop */
        for ( i = 0 ; i < SHA256_ROUNDS ; i++ ) {
                s0 = ( ror32 ( *a, 2 ) ^ ror32 ( *a, 13 ) ^ ror32 ( *a, 22 ) );
                maj = ( ( *a & *b ) ^ ( *a & *c ) ^ ( *b & *c ) );
                t2 = ( s0 + maj );
                s1 = ( ror32 ( *e, 6 ) ^ ror32 ( *e, 11 ) ^ ror32 ( *e, 25 ) );
                ch = ( ( *e & *f ) ^ ( (~*e) & *g ) );
                t1 = ( *h + s1 + ch + k[i] + w[i] );
                *h = *g;
                *g = *f;
                *f = *e;
                *e = ( *d + t1 );
                *d = *c;
                *c = *b;
                *b = *a;
                *a = ( t1 + t2 );
                DBGC2 ( context, "%2d : %08x %08x %08x %08x %08x %08x %08x "
                        "%08x\n", i, *a, *b, *c, *d, *e, *f, *g, *h );
        }

        /* Add chunk to hash and convert back to big-endian */
        for ( i = 0 ; i < 8 ; i++ ) {
                context->ddd.dd.digest.h[i] =
                        cpu_to_be32 ( context->ddd.dd.digest.h[i] +
                                      u.ddd.dd.digest.h[i] );
        }

        DBGC ( context, "SHA256 digested:\n" );
        DBGC_HDA ( context, 0, &context->ddd.dd.digest,
                   sizeof ( context->ddd.dd.digest ) );
}

/**
 * Accumulate data with SHA-256 algorithm
 *
 * @v ctx               SHA-256 context
 * @v data              Data
 * @v len               Length of data
 */
void sha256_update ( void *ctx, const void *data, size_t len ) {
        struct sha256_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 )
                        sha256_digest ( context );
        }
}

/**
 * Generate SHA-256 digest
 *
 * @v ctx               SHA-256 context
 * @v out               Output buffer
 */
void sha256_final ( void *ctx, void *out ) {
        struct sha256_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 {
                sha256_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) */
        sha256_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, context->digestsize );
}

/** SHA-256 algorithm */
struct digest_algorithm sha256_algorithm = {
        .name           = "sha256",
        .ctxsize        = sizeof ( struct sha256_context ),
        .blocksize      = sizeof ( union sha256_block ),
        .digestsize     = sizeof ( struct sha256_digest ),
        .init           = sha256_init,
        .update         = sha256_update,
        .final          = sha256_final,
};