ECP: Catch unsupported import/export
mbedtls_ecp_read_key() module returned without an error even when
importing keys corresponding to the requested group was not
implemented.
We change this and return an error when the requested group is not
supported and make the remaining import/export functions more robust.
diff --git a/library/ecp.c b/library/ecp.c
index f275605..c918c95 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -736,7 +736,7 @@
int format, size_t *olen,
unsigned char *buf, size_t buflen )
{
- int ret = 0;
+ int ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
size_t plen;
ECP_VALIDATE_RET( grp != NULL );
ECP_VALIDATE_RET( P != NULL );
@@ -758,7 +758,7 @@
}
#endif
#if defined(ECP_SHORTWEIERSTRASS)
- if( ecp_get_type( grp ) != ECP_TYPE_MONTGOMERY )
+ if( ecp_get_type( grp ) == ECP_TYPE_SHORT_WEIERSTRASS )
{
/*
* Common case: P == 0
@@ -809,7 +809,7 @@
mbedtls_ecp_point *pt,
const unsigned char *buf, size_t ilen )
{
- int ret;
+ int ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
size_t plen;
ECP_VALIDATE_RET( grp != NULL );
ECP_VALIDATE_RET( pt != NULL );
@@ -832,10 +832,12 @@
if( grp->id == MBEDTLS_ECP_DP_CURVE25519 )
/* Set most significant bit to 0 as prescribed in RFC7748 §5 */
MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &pt->X, plen * 8 - 1, 0 ) );
+
+ MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &pt->Z, 1 ) );
}
#endif
#if defined(ECP_SHORTWEIERSTRASS)
- if( ecp_get_type( grp ) != ECP_TYPE_MONTGOMERY )
+ if( ecp_get_type( grp ) == ECP_TYPE_SHORT_WEIERSTRASS )
{
if( buf[0] == 0x00 )
{
@@ -854,11 +856,10 @@
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &pt->X, buf + 1, plen ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &pt->Y,
buf + 1 + plen, plen ) );
+ MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &pt->Z, 1 ) );
}
#endif
- MBEDTLS_MPI_CHK( mbedtls_mpi_lset( &pt->Z, 1 ) );
-
cleanup:
return( ret );
}
@@ -2854,39 +2855,51 @@
{
int ret = 0;
+ ECP_VALIDATE_RET( key != NULL );
+ ECP_VALIDATE_RET( buf != NULL );
+
if( ( ret = mbedtls_ecp_group_load( &key->grp, grp_id ) ) != 0 )
return( ret );
-#if defined(MBEDTLS_ECP_DP_CURVE25519_ENABLED)
- /*
- * If it is Curve25519 curve then mask the key as mandated by RFC7748
- */
- if( grp_id == MBEDTLS_ECP_DP_CURVE25519 )
+ ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
+
+#if defined(ECP_MONTGOMERY)
+ if( ecp_get_type( &key->grp ) == ECP_TYPE_MONTGOMERY )
{
- if( buflen != ECP_CURVE25519_KEY_SIZE )
- return MBEDTLS_ERR_ECP_INVALID_KEY;
+ /*
+ * If it is Curve25519 curve then mask the key as mandated by RFC7748
+ */
+ if( grp_id == MBEDTLS_ECP_DP_CURVE25519 )
+ {
+ if( buflen != ECP_CURVE25519_KEY_SIZE )
+ return MBEDTLS_ERR_ECP_INVALID_KEY;
- MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary_le( &key->d, buf, buflen ) );
+ MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary_le( &key->d, buf, buflen ) );
- /* Set the three least significant bits to 0 */
- MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &key->d, 0, 0 ) );
- MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &key->d, 1, 0 ) );
- MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &key->d, 2, 0 ) );
+ /* Set the three least significant bits to 0 */
+ MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &key->d, 0, 0 ) );
+ MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &key->d, 1, 0 ) );
+ MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &key->d, 2, 0 ) );
- /* Set the most significant bit to 0 */
- MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &key->d,
- ECP_CURVE25519_KEY_SIZE * 8 - 1,
- 0 ) );
+ /* Set the most significant bit to 0 */
+ MBEDTLS_MPI_CHK(
+ mbedtls_mpi_set_bit( &key->d,
+ ECP_CURVE25519_KEY_SIZE * 8 - 1, 0 )
+ );
- /* Set the second most significant bit to 1 */
- MBEDTLS_MPI_CHK( mbedtls_mpi_set_bit( &key->d,
- ECP_CURVE25519_KEY_SIZE * 8 - 2,
- 1 ) );
+ /* Set the second most significant bit to 1 */
+ MBEDTLS_MPI_CHK(
+ mbedtls_mpi_set_bit( &key->d,
+ ECP_CURVE25519_KEY_SIZE * 8 - 2, 1 )
+ );
+ }
+ else
+ ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
}
#endif
#if defined(ECP_SHORTWEIERSTRASS)
- if( ecp_get_type( &key->grp ) != ECP_TYPE_MONTGOMERY )
+ if( ecp_get_type( &key->grp ) == ECP_TYPE_SHORT_WEIERSTRASS )
{
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary( &key->d, buf, buflen ) );