Diff: mbedtls/source/dhm.c

Revision:

13:bed103425508

Parent:

12:0071cb144c7a

Child:

14:79bcbfbb93c7

--- a/mbedtls/source/dhm.c	Tue Nov 01 14:22:56 2016 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,627 +0,0 @@
-/*
- *  Diffie-Hellman-Merkle key exchange
- *
- *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
- *  SPDX-License-Identifier: Apache-2.0
- *
- *  Licensed under the Apache License, Version 2.0 (the "License"); you may
- *  not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *  http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- *  This file is part of mbed TLS (https://tls.mbed.org)
- */
-/*
- *  The following sources were referenced in the design of this implementation
- *  of the Diffie-Hellman-Merkle algorithm:
- *
- *  [1] Handbook of Applied Cryptography - 1997, Chapter 12
- *      Menezes, van Oorschot and Vanstone
- *
- */
-
-#if !defined(MBEDTLS_CONFIG_FILE)
-#include "mbedtls/config.h"
-#else
-#include MBEDTLS_CONFIG_FILE
-#endif
-
-#if defined(MBEDTLS_DHM_C)
-
-#include "mbedtls/dhm.h"
-
-#include <string.h>
-
-#if defined(MBEDTLS_PEM_PARSE_C)
-#include "mbedtls/pem.h"
-#endif
-
-#if defined(MBEDTLS_ASN1_PARSE_C)
-#include "mbedtls/asn1.h"
-#endif
-
-#if defined(MBEDTLS_PLATFORM_C)
-#include "mbedtls/platform.h"
-#else
-#include <stdlib.h>
-#include <stdio.h>
-#define mbedtls_printf     pc.printf
-#define mbedtls_calloc    calloc
-#define mbedtls_free       free
-#endif
-
-/* Implementation that should never be optimized out by the compiler */
-static void mbedtls_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
-}
-
-/*
- * helper to validate the mbedtls_mpi size and import it
- */
-static int dhm_read_bignum( mbedtls_mpi *X,
-                            unsigned char **p,
-                            const unsigned char *end )
-{
-    int ret, n;
-
-    if( end - *p < 2 )
-        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
-
-    n = ( (*p)[0] << 8 ) | (*p)[1];
-    (*p) += 2;
-
-    if( (int)( end - *p ) < n )
-        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
-
-    if( ( ret = mbedtls_mpi_read_binary( X, *p, n ) ) != 0 )
-        return( MBEDTLS_ERR_DHM_READ_PARAMS_FAILED + ret );
-
-    (*p) += n;
-
-    return( 0 );
-}
-
-/*
- * Verify sanity of parameter with regards to P
- *
- * Parameter should be: 2 <= public_param <= P - 2
- *
- * For more information on the attack, see:
- *  http://www.cl.cam.ac.uk/~rja14/Papers/psandqs.pdf
- *  http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2005-2643
- */
-static int dhm_check_range( const mbedtls_mpi *param, const mbedtls_mpi *P )
-{
-    mbedtls_mpi L, U;
-    int ret = MBEDTLS_ERR_DHM_BAD_INPUT_DATA;
-
-    mbedtls_mpi_init( &L ); mbedtls_mpi_init( &U );
-
-    MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &L, 2 ) );
-    MBEDTLS_MPI_CHK( mbedtls_mpi_sub_int( &U, P, 2 ) );
-
-    if( mbedtls_mpi_cmp_mpi( param, &L ) >= 0 &&
-        mbedtls_mpi_cmp_mpi( param, &U ) <= 0 )
-    {
-        ret = 0;
-    }
-
-cleanup:
-    mbedtls_mpi_free( &L ); mbedtls_mpi_free( &U );
-    return( ret );
-}
-
-void mbedtls_dhm_init( mbedtls_dhm_context *ctx )
-{
-    memset( ctx, 0, sizeof( mbedtls_dhm_context ) );
-}
-
-/*
- * Parse the ServerKeyExchange parameters
- */
-int mbedtls_dhm_read_params( mbedtls_dhm_context *ctx,
-                     unsigned char **p,
-                     const unsigned char *end )
-{
-    int ret;
-
-    if( ( ret = dhm_read_bignum( &ctx->P,  p, end ) ) != 0 ||
-        ( ret = dhm_read_bignum( &ctx->G,  p, end ) ) != 0 ||
-        ( ret = dhm_read_bignum( &ctx->GY, p, end ) ) != 0 )
-        return( ret );
-
-    if( ( ret = dhm_check_range( &ctx->GY, &ctx->P ) ) != 0 )
-        return( ret );
-
-    ctx->len = mbedtls_mpi_size( &ctx->P );
-
-    return( 0 );
-}
-
-/*
- * Setup and write the ServerKeyExchange parameters
- */
-int mbedtls_dhm_make_params( mbedtls_dhm_context *ctx, int x_size,
-                     unsigned char *output, size_t *olen,
-                     int (*f_rng)(void *, unsigned char *, size_t),
-                     void *p_rng )
-{
-    int ret, count = 0;
-    size_t n1, n2, n3;
-    unsigned char *p;
-
-    if( mbedtls_mpi_cmp_int( &ctx->P, 0 ) == 0 )
-        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
-
-    /*
-     * Generate X as large as possible ( < P )
-     */
-    do
-    {
-        mbedtls_mpi_fill_random( &ctx->X, x_size, f_rng, p_rng );
-
-        while( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 )
-            MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->X, 1 ) );
-
-        if( count++ > 10 )
-            return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED );
-    }
-    while( dhm_check_range( &ctx->X, &ctx->P ) != 0 );
-
-    /*
-     * Calculate GX = G^X mod P
-     */
-    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->GX, &ctx->G, &ctx->X,
-                          &ctx->P , &ctx->RP ) );
-
-    if( ( ret = dhm_check_range( &ctx->GX, &ctx->P ) ) != 0 )
-        return( ret );
-
-    /*
-     * export P, G, GX
-     */
-#define DHM_MPI_EXPORT(X,n)                     \
-    MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, p + 2, n ) ); \
-    *p++ = (unsigned char)( n >> 8 );           \
-    *p++ = (unsigned char)( n      ); p += n;
-
-    n1 = mbedtls_mpi_size( &ctx->P  );
-    n2 = mbedtls_mpi_size( &ctx->G  );
-    n3 = mbedtls_mpi_size( &ctx->GX );
-
-    p = output;
-    DHM_MPI_EXPORT( &ctx->P , n1 );
-    DHM_MPI_EXPORT( &ctx->G , n2 );
-    DHM_MPI_EXPORT( &ctx->GX, n3 );
-
-    *olen  = p - output;
-
-    ctx->len = n1;
-
-cleanup:
-
-    if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED + ret );
-
-    return( 0 );
-}
-
-/*
- * Import the peer's public value G^Y
- */
-int mbedtls_dhm_read_public( mbedtls_dhm_context *ctx,
-                     const unsigned char *input, size_t ilen )
-{
-    int ret;
-
-    if( ctx == NULL || ilen < 1 || ilen > ctx->len )
-        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
-
-    if( ( ret = mbedtls_mpi_read_binary( &ctx->GY, input, ilen ) ) != 0 )
-        return( MBEDTLS_ERR_DHM_READ_PUBLIC_FAILED + ret );
-
-    return( 0 );
-}
-
-/*
- * Create own private value X and export G^X
- */
-int mbedtls_dhm_make_public( mbedtls_dhm_context *ctx, int x_size,
-                     unsigned char *output, size_t olen,
-                     int (*f_rng)(void *, unsigned char *, size_t),
-                     void *p_rng )
-{
-    int ret, count = 0;
-
-    if( ctx == NULL || olen < 1 || olen > ctx->len )
-        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
-
-    if( mbedtls_mpi_cmp_int( &ctx->P, 0 ) == 0 )
-        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
-
-    /*
-     * generate X and calculate GX = G^X mod P
-     */
-    do
-    {
-        mbedtls_mpi_fill_random( &ctx->X, x_size, f_rng, p_rng );
-
-        while( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->P ) >= 0 )
-            MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->X, 1 ) );
-
-        if( count++ > 10 )
-            return( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED );
-    }
-    while( dhm_check_range( &ctx->X, &ctx->P ) != 0 );
-
-    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->GX, &ctx->G, &ctx->X,
-                          &ctx->P , &ctx->RP ) );
-
-    if( ( ret = dhm_check_range( &ctx->GX, &ctx->P ) ) != 0 )
-        return( ret );
-
-    MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->GX, output, olen ) );
-
-cleanup:
-
-    if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED + ret );
-
-    return( 0 );
-}
-
-/*
- * Use the blinding method and optimisation suggested in section 10 of:
- *  KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA,
- *  DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer
- *  Berlin Heidelberg, 1996. p. 104-113.
- */
-static int dhm_update_blinding( mbedtls_dhm_context *ctx,
-                    int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
-{
-    int ret, count;
-
-    /*
-     * Don't use any blinding the first time a particular X is used,
-     * but remember it to use blinding next time.
-     */
-    if( mbedtls_mpi_cmp_mpi( &ctx->X, &ctx->pX ) != 0 )
-    {
-        MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &ctx->pX, &ctx->X ) );
-        MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->Vi, 1 ) );
-        MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &ctx->Vf, 1 ) );
-
-        return( 0 );
-    }
-
-    /*
-     * Ok, we need blinding. Can we re-use existing values?
-     * If yes, just update them by squaring them.
-     */
-    if( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) != 0 )
-    {
-        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vi, &ctx->Vi, &ctx->Vi ) );
-        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vi, &ctx->Vi, &ctx->P ) );
-
-        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->Vf, &ctx->Vf, &ctx->Vf ) );
-        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->Vf, &ctx->Vf, &ctx->P ) );
-
-        return( 0 );
-    }
-
-    /*
-     * We need to generate blinding values from scratch
-     */
-
-    /* Vi = random( 2, P-1 ) */
-    count = 0;
-    do
-    {
-        mbedtls_mpi_fill_random( &ctx->Vi, mbedtls_mpi_size( &ctx->P ), f_rng, p_rng );
-
-        while( mbedtls_mpi_cmp_mpi( &ctx->Vi, &ctx->P ) >= 0 )
-            MBEDTLS_MPI_CHK( mbedtls_mpi_shift_r( &ctx->Vi, 1 ) );
-
-        if( count++ > 10 )
-            return( MBEDTLS_ERR_MPI_NOT_ACCEPTABLE );
-    }
-    while( mbedtls_mpi_cmp_int( &ctx->Vi, 1 ) <= 0 );
-
-    /* Vf = Vi^-X mod P */
-    MBEDTLS_MPI_CHK( mbedtls_mpi_inv_mod( &ctx->Vf, &ctx->Vi, &ctx->P ) );
-    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->Vf, &ctx->Vf, &ctx->X, &ctx->P, &ctx->RP ) );
-
-cleanup:
-    return( ret );
-}
-
-/*
- * Derive and export the shared secret (G^Y)^X mod P
- */
-int mbedtls_dhm_calc_secret( mbedtls_dhm_context *ctx,
-                     unsigned char *output, size_t output_size, size_t *olen,
-                     int (*f_rng)(void *, unsigned char *, size_t),
-                     void *p_rng )
-{
-    int ret;
-    mbedtls_mpi GYb;
-
-    if( ctx == NULL || output_size < ctx->len )
-        return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
-
-    if( ( ret = dhm_check_range( &ctx->GY, &ctx->P ) ) != 0 )
-        return( ret );
-
-    mbedtls_mpi_init( &GYb );
-
-    /* Blind peer's value */
-    if( f_rng != NULL )
-    {
-        MBEDTLS_MPI_CHK( dhm_update_blinding( ctx, f_rng, p_rng ) );
-        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &GYb, &ctx->GY, &ctx->Vi ) );
-        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &GYb, &GYb, &ctx->P ) );
-    }
-    else
-        MBEDTLS_MPI_CHK( mbedtls_mpi_copy( &GYb, &ctx->GY ) );
-
-    /* Do modular exponentiation */
-    MBEDTLS_MPI_CHK( mbedtls_mpi_exp_mod( &ctx->K, &GYb, &ctx->X,
-                          &ctx->P, &ctx->RP ) );
-
-    /* Unblind secret value */
-    if( f_rng != NULL )
-    {
-        MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &ctx->K, &ctx->K, &ctx->Vf ) );
-        MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &ctx->K, &ctx->K, &ctx->P ) );
-    }
-
-    *olen = mbedtls_mpi_size( &ctx->K );
-
-    MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &ctx->K, output, *olen ) );
-
-cleanup:
-    mbedtls_mpi_free( &GYb );
-
-    if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_CALC_SECRET_FAILED + ret );
-
-    return( 0 );
-}
-
-/*
- * Free the components of a DHM key
- */
-void mbedtls_dhm_free( mbedtls_dhm_context *ctx )
-{
-    mbedtls_mpi_free( &ctx->pX); mbedtls_mpi_free( &ctx->Vf ); mbedtls_mpi_free( &ctx->Vi );
-    mbedtls_mpi_free( &ctx->RP ); mbedtls_mpi_free( &ctx->K ); mbedtls_mpi_free( &ctx->GY );
-    mbedtls_mpi_free( &ctx->GX ); mbedtls_mpi_free( &ctx->X ); mbedtls_mpi_free( &ctx->G );
-    mbedtls_mpi_free( &ctx->P );
-
-    mbedtls_zeroize( ctx, sizeof( mbedtls_dhm_context ) );
-}
-
-#if defined(MBEDTLS_ASN1_PARSE_C)
-/*
- * Parse DHM parameters
- */
-int mbedtls_dhm_parse_dhm( mbedtls_dhm_context *dhm, const unsigned char *dhmin,
-                   size_t dhminlen )
-{
-    int ret;
-    size_t len;
-    unsigned char *p, *end;
-#if defined(MBEDTLS_PEM_PARSE_C)
-    mbedtls_pem_context pem;
-
-    mbedtls_pem_init( &pem );
-
-    /* Avoid calling mbedtls_pem_read_buffer() on non-null-terminated string */
-    if( dhminlen == 0 || dhmin[dhminlen - 1] != '\0' )
-        ret = MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT;
-    else
-        ret = mbedtls_pem_read_buffer( &pem,
-                               "-----BEGIN DH PARAMETERS-----",
-                               "-----END DH PARAMETERS-----",
-                               dhmin, NULL, 0, &dhminlen );
-
-    if( ret == 0 )
-    {
-        /*
-         * Was PEM encoded
-         */
-        dhminlen = pem.buflen;
-    }
-    else if( ret != MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT )
-        goto exit;
-
-    p = ( ret == 0 ) ? pem.buf : (unsigned char *) dhmin;
-#else
-    p = (unsigned char *) dhmin;
-#endif /* MBEDTLS_PEM_PARSE_C */
-    end = p + dhminlen;
-
-    /*
-     *  DHParams ::= SEQUENCE {
-     *      prime              INTEGER,  -- P
-     *      generator          INTEGER,  -- g
-     *      privateValueLength INTEGER OPTIONAL
-     *  }
-     */
-    if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
-            MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-    {
-        ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
-        goto exit;
-    }
-
-    end = p + len;
-
-    if( ( ret = mbedtls_asn1_get_mpi( &p, end, &dhm->P  ) ) != 0 ||
-        ( ret = mbedtls_asn1_get_mpi( &p, end, &dhm->G ) ) != 0 )
-    {
-        ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
-        goto exit;
-    }
-
-    if( p != end )
-    {
-        /* This might be the optional privateValueLength.
-         * If so, we can cleanly discard it */
-        mbedtls_mpi rec;
-        mbedtls_mpi_init( &rec );
-        ret = mbedtls_asn1_get_mpi( &p, end, &rec );
-        mbedtls_mpi_free( &rec );
-        if ( ret != 0 )
-        {
-            ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
-            goto exit;
-        }
-        if ( p != end )
-        {
-            ret = MBEDTLS_ERR_DHM_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
-            goto exit;
-        }
-    }
-
-    ret = 0;
-
-    dhm->len = mbedtls_mpi_size( &dhm->P );
-
-exit:
-#if defined(MBEDTLS_PEM_PARSE_C)
-    mbedtls_pem_free( &pem );
-#endif
-    if( ret != 0 )
-        mbedtls_dhm_free( dhm );
-
-    return( ret );
-}
-
-#if defined(MBEDTLS_FS_IO)
-/*
- * Load all data from a file into a given buffer.
- *
- * The file is expected to contain either PEM or DER encoded data.
- * A terminating null byte is always appended. It is included in the announced
- * length only if the data looks like it is PEM encoded.
- */
-static int load_file( const char *path, unsigned char **buf, size_t *n )
-{
-    FILE *f;
-    long size;
-
-    if( ( f = fopen( path, "rb" ) ) == NULL )
-        return( MBEDTLS_ERR_DHM_FILE_IO_ERROR );
-
-    fseek( f, 0, SEEK_END );
-    if( ( size = ftell( f ) ) == -1 )
-    {
-        fclose( f );
-        return( MBEDTLS_ERR_DHM_FILE_IO_ERROR );
-    }
-    fseek( f, 0, SEEK_SET );
-
-    *n = (size_t) size;
-
-    if( *n + 1 == 0 ||
-        ( *buf = mbedtls_calloc( 1, *n + 1 ) ) == NULL )
-    {
-        fclose( f );
-        return( MBEDTLS_ERR_DHM_ALLOC_FAILED );
-    }
-
-    if( fread( *buf, 1, *n, f ) != *n )
-    {
-        fclose( f );
-        mbedtls_free( *buf );
-        return( MBEDTLS_ERR_DHM_FILE_IO_ERROR );
-    }
-
-    fclose( f );
-
-    (*buf)[*n] = '\0';
-
-    if( strstr( (const char *) *buf, "-----BEGIN " ) != NULL )
-        ++*n;
-
-    return( 0 );
-}
-
-/*
- * Load and parse DHM parameters
- */
-int mbedtls_dhm_parse_dhmfile( mbedtls_dhm_context *dhm, const char *path )
-{
-    int ret;
-    size_t n;
-    unsigned char *buf;
-
-    if( ( ret = load_file( path, &buf, &n ) ) != 0 )
-        return( ret );
-
-    ret = mbedtls_dhm_parse_dhm( dhm, buf, n );
-
-    mbedtls_zeroize( buf, n );
-    mbedtls_free( buf );
-
-    return( ret );
-}
-#endif /* MBEDTLS_FS_IO */
-#endif /* MBEDTLS_ASN1_PARSE_C */
-
-#if defined(MBEDTLS_SELF_TEST)
-
-static const char mbedtls_test_dhm_params[] =
-"-----BEGIN DH PARAMETERS-----\r\n"
-"MIGHAoGBAJ419DBEOgmQTzo5qXl5fQcN9TN455wkOL7052HzxxRVMyhYmwQcgJvh\r\n"
-"1sa18fyfR9OiVEMYglOpkqVoGLN7qd5aQNNi5W7/C+VBdHTBJcGZJyyP5B3qcz32\r\n"
-"9mLJKudlVudV0Qxk5qUJaPZ/xupz0NyoVpviuiBOI1gNi8ovSXWzAgEC\r\n"
-"-----END DH PARAMETERS-----\r\n";
-
-static const size_t mbedtls_test_dhm_params_len = sizeof( mbedtls_test_dhm_params );
-
-/*
- * Checkup routine
- */
-int mbedtls_dhm_self_test( int verbose )
-{
-    int ret;
-    mbedtls_dhm_context dhm;
-
-    mbedtls_dhm_init( &dhm );
-
-    if( verbose != 0 )
-        mbedtls_printf( "  DHM parameter load: " );
-
-    if( ( ret = mbedtls_dhm_parse_dhm( &dhm,
-                    (const unsigned char *) mbedtls_test_dhm_params,
-                    mbedtls_test_dhm_params_len ) ) != 0 )
-    {
-        if( verbose != 0 )
-            mbedtls_printf( "failed\n" );
-
-        ret = 1;
-        goto exit;
-    }
-
-    if( verbose != 0 )
-        mbedtls_printf( "passed\n\n" );
-
-exit:
-    mbedtls_dhm_free( &dhm );
-
-    return( ret );
-}
-
-#endif /* MBEDTLS_SELF_TEST */
-
-#endif /* MBEDTLS_DHM_C */