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Add missing Curve448 support for PSA keys

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mbedtls_ecp_read_key and mbedtls_ecp_write_key are updated to include
support for Curve448 as prescribed by RFC 7748 §5.

Test suites have been updated to validate curve448 under Montgomery
curves.

Signed-off-by: Archana <archana.madhavan@silabs.com>
This commit is contained in:
Archana
2021-06-07 06:13:16 +05:30
parent ac694b9eac
commit 1d2e2bb8cc
2 changed files with 119 additions and 20 deletions
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32
library/ecp.c
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@ -3054,6 +3054,7 @@ int mbedtls_ecp_gen_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
}
#define ECP_CURVE25519_KEY_SIZE 32
#define ECP_CURVE448_KEY_SIZE 56
/*
* Read a private key.
*/
@ -3074,7 +3075,7 @@ int mbedtls_ecp_read_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
if( mbedtls_ecp_get_type( &key->grp ) == MBEDTLS_ECP_TYPE_MONTGOMERY )
{
/*
* If it is Curve25519 curve then mask the key as mandated by RFC7748
* Mask the key as mandated by RFC7748 for Curve25519 and Curve448.
*/
if( grp_id == MBEDTLS_ECP_DP_CURVE25519 )
{
@ -3100,8 +3101,23 @@ int mbedtls_ecp_read_key( mbedtls_ecp_group_id grp_id, mbedtls_ecp_keypair *key,
ECP_CURVE25519_KEY_SIZE * 8 - 2, 1 )
);
}
else
ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
else if( grp_id == MBEDTLS_ECP_DP_CURVE448 )
{
if( buflen != ECP_CURVE448_KEY_SIZE )
return MBEDTLS_ERR_ECP_INVALID_KEY;
MBEDTLS_MPI_CHK( mbedtls_mpi_read_binary_le( &key->d, buf, buflen ) );
/* Set the two 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 ) );
/* Set the most significant bit to 1 */
MBEDTLS_MPI_CHK(
mbedtls_mpi_set_bit( &key->d,
ECP_CURVE448_KEY_SIZE * 8 - 1, 1 )
);
}
}
#endif
@ -3141,12 +3157,14 @@ int mbedtls_ecp_write_key( mbedtls_ecp_keypair *key,
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 ) );
}
else
ret = MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE;
else if ( key->grp.id == MBEDTLS_ECP_DP_CURVE448 )
{
if( buflen < ECP_CURVE448_KEY_SIZE )
return MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL;
}
MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary_le( &key->d, buf, buflen ) );
}
#endif
#if defined(MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED)
if( mbedtls_ecp_get_type( &key->grp ) == MBEDTLS_ECP_TYPE_SHORT_WEIERSTRASS )