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ECP: Catch unsupported import/export

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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.
This commit is contained in:
Janos Follath
2019-02-26 10:53:34 +00:00
parent b65853c6b6
commit 28eb06df16
3 changed files with 57 additions and 32 deletions
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67
library/ecp.c
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@ -736,7 +736,7 @@ int mbedtls_ecp_point_write_binary( const mbedtls_ecp_group *grp,
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 @@ int mbedtls_ecp_point_write_binary( const mbedtls_ecp_group *grp,
}
#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 @@ int mbedtls_ecp_point_read_binary( const mbedtls_ecp_group *grp,
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 @@ int mbedtls_ecp_point_read_binary( const mbedtls_ecp_group *grp,
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 @@ int mbedtls_ecp_point_read_binary( const mbedtls_ecp_group *grp,
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 mbedtls_ecp_read_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
{
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 ) );