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Use new HMAC_DRBG module for deterministic ECDSA

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Manuel Pégourié-Gonnard 2014-01-27 14:24:03 +01:00
parent 490bdf3928
commit 7845fc06c9
2 changed files with 5 additions and 96 deletions
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4
include/polarssl/config.h
View file

@ -290,7 +290,7 @@
* may result in a compromise of the long-term signing key. This is avoided by
* the deterministic variant.
*
* Requires: POLARSSL_MD_C
* Requires: POLARSSL_HMAC_DRBG_C
*
* Comment this macro to disable deterministic ECDSA.
*/
@ -1976,7 +1976,7 @@
#error "POLARSSL_ECDSA_C defined, but not all prerequisites"
#endif
#if defined(POLARSSL_ECDSA_DETERMINISTIC) && !defined(POLARSSL_MD_C)
#if defined(POLARSSL_ECDSA_DETERMINISTIC) && !defined(POLARSSL_HMAC_DRBG_C)
#error "POLARSSL_ECDSA_DETERMINISTIC defined, but not all prerequisites"
#endif

97
library/ecdsa.c
View file

@ -37,101 +37,10 @@
#include "polarssl/asn1write.h"
#if defined(POLARSSL_ECDSA_DETERMINISTIC)
/*
* Simplified HMAC_DRBG context.
* No reseed counter, no prediction resistance flag.
*/
typedef struct
{
md_context_t md_ctx;
unsigned char V[POLARSSL_MD_MAX_SIZE];
unsigned char K[POLARSSL_MD_MAX_SIZE];
} hmac_drbg_context;
/*
* Simplified HMAC_DRBG update, using optional additional data
*/
static void hmac_drbg_update( hmac_drbg_context *ctx,
const unsigned char *data, size_t data_len )
{
size_t md_len = ctx->md_ctx.md_info->size;
unsigned char rounds = ( data != NULL && data_len != 0 ) ? 2 : 1;
unsigned char sep[1];
for( sep[0] = 0; sep[0] < rounds; sep[0]++ )
{
md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
md_hmac_update( &ctx->md_ctx, sep, 1 );
if( rounds == 2 )
md_hmac_update( &ctx->md_ctx, data, data_len );
md_hmac_finish( &ctx->md_ctx, ctx->K );
md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
md_hmac_finish( &ctx->md_ctx, ctx->V );
}
}
/*
* Simplified HMAC_DRBG initialisation.
*
* Uses an entropy buffer rather than callback,
* assume personalisation string is included in entropy buffer,
* assumes md_info is not NULL and valid.
*/
static void hmac_drbg_init( hmac_drbg_context *ctx,
const md_info_t * md_info,
const unsigned char *data, size_t data_len )
{
memset( ctx, 0, sizeof( hmac_drbg_context ) );
md_init_ctx( &ctx->md_ctx, md_info );
memset( ctx->V, 0x01, md_info->size );
/* ctx->K is already 0 */
hmac_drbg_update( ctx, data, data_len );
}
/*
* Simplified HMAC_DRBG random function
*/
static int hmac_drbg_random( void *state,
unsigned char *output, size_t out_len )
{
hmac_drbg_context *ctx = (hmac_drbg_context *) state;
size_t md_len = ctx->md_ctx.md_info->size;
size_t left = out_len;
unsigned char *out = output;
while( left != 0 )
{
size_t use_len = left > md_len ? md_len : left;
md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
md_hmac_finish( &ctx->md_ctx, ctx->V );
memcpy( out, ctx->V, use_len );
out += use_len;
left -= use_len;
}
hmac_drbg_update( ctx, NULL, 0 );
return( 0 );
}
static void hmac_drbg_free( hmac_drbg_context *ctx )
{
if( ctx == NULL )
return;
md_free_ctx( &ctx->md_ctx );
memset( ctx, 0, sizeof( hmac_drbg_context ) );
}
#include "polarssl/hmac_drbg.h"
#endif
#if defined(POLARSSL_ECDSA_DETERMINISTIC)
/*
* This a hopefully temporary compatibility function.
*