Implement and test mbedtls_ecp_write_key

mbedtls_ecp_write_key is a mirror function to mbedtls_ecp_read_key, which
writes a private key back into a byte buffer in the correct format.
This is a helpful convenience function, since the byte order is defined
differently between Montgomery and Weierstrass curves. Since this difference
is accounted for in mbedtls_ecp_read_key, it made sense to add
mbedtls_ecp_write_key for the purpose of abstracting this away such that
psa_export_key doesn't need to take byte order into account.

Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
This commit is contained in:
Steven Cooreman 2020-06-09 19:55:26 +02:00
parent 0af1560919
commit de8593f2fe
4 changed files with 133 additions and 17 deletions

View file

@ -1146,6 +1146,27 @@ int mbedtls_ecp_gen_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
*/
int mbedtls_ecp_read_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
const unsigned char *buf, size_t buflen );
/**
* \brief This function exports an elliptic curve private key.
*
* \param grp_id The ECP group identifier.
* \param key The private key.
* \param olen The amount of bytes written into the output buffer.
* \param buf The output buffer containing the binary representation of
* the key. (Big endian integer for Weierstrass curves, byte
* string for Montgomery curves.)
* \param buflen The total length of the buffer in bytes.
*
* \return \c 0 on success.
* \return #MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL if key is larger than buffer.
* \return #MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE if the operation for
* the group is not implemented.
* \return Another negative error code on different kinds of failure.
*/
int mbedtls_ecp_write_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
size_t *olen, unsigned char *buf, size_t buflen );
/**
* \brief This function checks that the keypair objects
* \p pub and \p prv have the same group and the

View file

@ -2996,6 +2996,53 @@ cleanup:
return( ret );
}
/*
* Write a private key.
*/
int mbedtls_ecp_write_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
size_t *olen, unsigned char *buf, size_t buflen )
{
int ret = 0;
ECP_VALIDATE_RET( key != NULL );
ECP_VALIDATE_RET( buf != NULL );
ECP_VALIDATE_RET( olen != NULL );
if( ( ret = mbedtls_ecp_group_load( &key->grp, grp_id ) ) != 0 )
return( ret );
ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
#if defined(ECP_MONTGOMERY)
if( mbedtls_ecp_get_type( &key->grp ) == MBEDTLS_ECP_TYPE_MONTGOMERY )
{
if( grp_id == MBEDTLS_ECP_DP_CURVE25519 )
{
if( buflen < ECP_CURVE25519_KEY_SIZE )
return MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL;
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary_le( &key->d, buf, buflen ) );
*olen = ECP_CURVE25519_KEY_SIZE;
}
else
ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
}
#endif
#if defined(ECP_SHORTWEIERSTRASS)
if( mbedtls_ecp_get_type( &key->grp ) == MBEDTLS_ECP_TYPE_SHORT_WEIERSTRASS )
{
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &key->d, buf, buflen ) );
*olen = mbedtls_mpi_size( &key->d );
}
#endif
cleanup:
return( ret );
}
/*
* Check a public-private key pair
*/

View file

@ -278,65 +278,69 @@ mbedtls_ecp_gen_key:MBEDTLS_ECP_DP_SECP192R1
ECP read key #1 (short weierstrass, too small)
depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_SECP192R1:"00":MBEDTLS_ERR_ECP_INVALID_KEY
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_SECP192R1:"00":MBEDTLS_ERR_ECP_INVALID_KEY:0
ECP read key #2 (short weierstrass, smallest)
depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_SECP192R1:"01":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_SECP192R1:"01":0:1
ECP read key #3 (short weierstrass, biggest)
depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_SECP192R1:"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22830":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_SECP192R1:"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22830":0:1
ECP read key #4 (short weierstrass, too big)
depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_SECP192R1:"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22831":MBEDTLS_ERR_ECP_INVALID_KEY
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_SECP192R1:"FFFFFFFFFFFFFFFFFFFFFFFF99DEF836146BC9B1B4D22831":MBEDTLS_ERR_ECP_INVALID_KEY:0
ECP read key #5 (Curve25519, most significant bit set)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"000000000000000000000000000000000000000000000000000000000000000C":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"000000000000000000000000000000000000000000000000000000000000000C":0:0
ECP read key #6 (Curve25519, second most significant bit unset)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"0FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF3":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"0FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF3":0:0
ECP read key #7 (Curve25519, msb OK)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"0000000000000000000000000000000000000000000000000000000000000004":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"0000000000000000000000000000000000000000000000000000000000000004":0:1
ECP read key #8 (Curve25519, bit 0 set)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"1000000000000000000000000000000000000000000000000000000000000000":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"1000000000000000000000000000000000000000000000000000000000000000":0:0
ECP read key #9 (Curve25519, bit 1 set)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"2000000000000000000000000000000000000000000000000000000000000004":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"2000000000000000000000000000000000000000000000000000000000000004":0:0
ECP read key #10 (Curve25519, bit 2 set)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"4000000000000000000000000000000000000000000000000000000000000004":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"4000000000000000000000000000000000000000000000000000000000000004":0:0
ECP read key #11 (Curve25519, OK)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"8FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7":0
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"8FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7":0:1
ECP read key #12 (Curve25519, too long)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"00000000000000000000000000000000000000000000000000000000000000000C":MBEDTLS_ERR_ECP_INVALID_KEY
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"00000000000000000000000000000000000000000000000000000000000000000C":MBEDTLS_ERR_ECP_INVALID_KEY:0
ECP read key #13 (Curve25519, not long enough)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"0FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF3":MBEDTLS_ERR_ECP_INVALID_KEY
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"0FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF3":MBEDTLS_ERR_ECP_INVALID_KEY:0
ECP read key #14 (Curve448, not supported)
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE448:"FCFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF":MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE448:"FCFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF":MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE:0
ECP read key #15 (Curve25519, not supported)
depends_on:!MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"8FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7":MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"8FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7":MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE:0
ECP read key #15 (invalid curve)
mbedtls_ecp_read_key:INT_MAX:"8FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7":MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE
mbedtls_ecp_read_key:INT_MAX:"8FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF7":MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE:0
ECP read key #16 (Curve25519 RFC, OK)
depends_on:MBEDTLS_ECP_DP_CURVE25519_ENABLED
mbedtls_ecp_read_key:MBEDTLS_ECP_DP_CURVE25519:"70076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c6a":0:1
ECP mod p192 small (more than 192 bits, less limbs than 2 * 192 bits)
depends_on:MBEDTLS_ECP_DP_SECP192R1_ENABLED

View file

@ -1069,12 +1069,14 @@ exit:
/* END_CASE */
/* BEGIN_CASE */
void mbedtls_ecp_read_key( int grp_id, data_t* in_key, int expected )
void mbedtls_ecp_read_key( int grp_id, data_t* in_key, int expected, int canonical )
{
int ret = 0;
mbedtls_ecp_keypair key;
mbedtls_ecp_keypair key2;
mbedtls_ecp_keypair_init( &key );
mbedtls_ecp_keypair_init( &key2 );
ret = mbedtls_ecp_read_key( grp_id, &key, in_key->x, in_key->len );
TEST_ASSERT( ret == expected );
@ -1083,10 +1085,52 @@ void mbedtls_ecp_read_key( int grp_id, data_t* in_key, int expected )
{
ret = mbedtls_ecp_check_privkey( &key.grp, &key.d );
TEST_ASSERT( ret == 0 );
if( canonical )
{
unsigned char buf[MBEDTLS_ECP_MAX_BYTES];
size_t olen;
ret = mbedtls_ecp_write_key( grp_id, &key, &olen, buf, in_key->len );
TEST_ASSERT( ret == 0 );
TEST_ASSERT( olen == in_key->len );
mbedtls_fprintf( stdout, "written key: ");
for( size_t i = 0; i < in_key->len; i++ ) {
mbedtls_fprintf( stdout, "%02x", buf[i]);
}
mbedtls_fprintf( stdout, "\n");
ASSERT_COMPARE( in_key->x, in_key->len,
buf, olen );
}
else
{
unsigned char export1[MBEDTLS_ECP_MAX_BYTES];
size_t olen1;
unsigned char export2[MBEDTLS_ECP_MAX_BYTES];
size_t olen2;
ret = mbedtls_ecp_write_key( grp_id, &key, &olen1, export1, in_key->len );
TEST_ASSERT( ret == 0 );
ret = mbedtls_ecp_read_key( grp_id, &key2, export1, in_key->len );
TEST_ASSERT( ret == expected );
ret = mbedtls_ecp_write_key( grp_id, &key2, &olen2, export2, in_key->len );
TEST_ASSERT( ret == 0 );
TEST_ASSERT( olen2 == olen1 );
ASSERT_COMPARE( export1, olen1,
export2, olen2 );
}
}
exit:
mbedtls_ecp_keypair_free( &key );
mbedtls_ecp_keypair_free( &key2 );
}
/* END_CASE */