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Add writing of server params

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This commit is contained in:
Manuel Pégourié-Gonnard 2015-08-13 18:53:59 +02:00
parent 8d31e80da4
commit bed9e41761
1 changed files with 96 additions and 9 deletions
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105
library/ecjpake.c
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@ -499,6 +499,29 @@ int mbedtls_ecjpake_tls_write_server_ext( mbedtls_ecjpake_context *ctx,
"server", buf, len, olen, f_rng, p_rng ) );
}
/*
* Compute the sum of three points R = A + B + C
*/
static int ecjpake_ecp_add3( mbedtls_ecp_group *grp, mbedtls_ecp_point *R,
const mbedtls_ecp_point *A,
const mbedtls_ecp_point *B,
const mbedtls_ecp_point *C )
{
int ret;
mbedtls_mpi one;
mbedtls_mpi_init( &one );
MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &one, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( grp, R, &one, A, &one, B ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( grp, R, &one, R, &one, C ) );
cleanup:
mbedtls_mpi_free( &one );
return( ret );
}
/*
* Read and process ServerECJPAKEParams (7.4.2.5)
*/
@ -511,21 +534,16 @@ int mbedtls_ecjpake_tls_read_server_params( mbedtls_ecjpake_context *ctx,
const unsigned char *end = buf + len;
mbedtls_ecp_group grp;
mbedtls_ecp_point GB;
mbedtls_mpi one;
mbedtls_ecp_group_init( &grp );
mbedtls_ecp_point_init( &GB );
mbedtls_mpi_init( &one );
/*
* We need that before parsing in order to check Xs as we read it
* GB = X1 + X2 + X3 (7.4.2.5.1)
* We need that before parsing in order to check Xs as we read it
*/
MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &one, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( &ctx->grp, &GB, &one, &ctx->X1,
&one, &ctx->X2 ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_muladd( &ctx->grp, &GB, &one, &GB,
&one, &ctx->X3 ) );
MBEDTLS_MPI_CHK( ecjpake_ecp_add3( &ctx->grp, &GB,
&ctx->X1, &ctx->X2, &ctx->X3 ) );
/*
* struct {
@ -555,7 +573,71 @@ int mbedtls_ecjpake_tls_read_server_params( mbedtls_ecjpake_context *ctx,
cleanup:
mbedtls_ecp_group_free( &grp );
mbedtls_ecp_point_free( &GB );
mbedtls_mpi_free( &one );
return( ret );
}
/*
* Generate and write ServerECJPAKEParams (7.4.2.5)
*/
int mbedtls_ecjpake_tls_write_server_params( mbedtls_ecjpake_context *ctx,
unsigned char *buf, size_t len, size_t *olen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
int ret;
mbedtls_ecp_point GB, Xs;
mbedtls_mpi xs;
unsigned char *p = buf;
const unsigned char *end = buf + len;
size_t ec_len;
if( end < *p )
return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
mbedtls_ecp_point_init( &GB );
mbedtls_ecp_point_init( &Xs );
mbedtls_mpi_init( &xs );
/*
* First generate private/public key pair (7.4.2.5.1)
*
* GB = X1 + X2 + X3
* xs = x4 * s mod n
* Xs = xs * GB
*/
MBEDTLS_MPI_CHK( ecjpake_ecp_add3( &ctx->grp, &GB,
&ctx->X1, &ctx->X2, &ctx->X3 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mpi( &xs, &ctx->xb, &ctx->s ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( &xs, &xs, &ctx->grp.N ) );
MBEDTLS_MPI_CHK( mbedtls_ecp_mul( &ctx->grp, &Xs, &xs, &GB, f_rng, p_rng ) );
/*
* Now write things out
*/
MBEDTLS_MPI_CHK( mbedtls_ecp_tls_write_group( &ctx->grp, &ec_len,
p, end - p ) );
p += ec_len;
if( end < p )
{
ret = MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL;
goto cleanup;
}
MBEDTLS_MPI_CHK( mbedtls_ecp_tls_write_point( &ctx->grp, &Xs,
MBEDTLS_ECP_PF_UNCOMPRESSED, &ec_len, p, end - p ) );
p += ec_len;
MBEDTLS_MPI_CHK( ecjpake_zkp_write( ctx->md_info, &ctx->grp,
&GB, &xs, &Xs, "server",
&p, end, f_rng, p_rng ) );
*olen = p - buf;
cleanup:
mbedtls_ecp_point_free( &GB );
mbedtls_ecp_point_free( &Xs );
mbedtls_mpi_free( &xs );
return( ret );
}
@ -759,6 +841,11 @@ int mbedtls_ecjpake_self_test( int verbose )
TEST_ASSERT( mbedtls_ecjpake_tls_read_server_ext( &cli, buf, len ) == 0 );
TEST_ASSERT( mbedtls_ecjpake_tls_write_server_params( &srv,
buf, sizeof( buf ), &len, ecjpake_lgc, NULL ) == 0 );
TEST_ASSERT( mbedtls_ecjpake_tls_read_server_params( &cli, buf, len ) == 0 );
if( verbose != 0 )
mbedtls_printf( "passed\n" );