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PSA: EC curve size macro #107

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Merged
merged 2 commits into from
May 16, 2019
Merged

PSA: EC curve size macro #107

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6c95144
New macro to get the bit size of an elliptic curve
gilles-peskine-arm May 13, 2019
c9d910b
EC key pair import: check the buffer size
gilles-peskine-arm May 13, 2019
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41 changes: 41 additions & 0 deletions include/psa/crypto_sizes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -187,6 +187,47 @@
#define PSA_VENDOR_ECC_MAX_CURVE_BITS 0
#endif

/** Bit size associated with an elliptic curve.
*
* \param curve An elliptic curve (value of type #psa_ecc_curve_t).
*
* \return The size associated with \p curve, in bits.
* This may be 0 if the implementation does not support
* the specified curve.
*/
#define PSA_ECC_CURVE_BITS(curve) \
((curve) == PSA_ECC_CURVE_SECT163K1 ? 163 : \
(curve) == PSA_ECC_CURVE_SECT163R1 ? 163 : \
(curve) == PSA_ECC_CURVE_SECT163R2 ? 163 : \
(curve) == PSA_ECC_CURVE_SECT193R1 ? 193 : \
(curve) == PSA_ECC_CURVE_SECT193R2 ? 193 : \
(curve) == PSA_ECC_CURVE_SECT233K1 ? 233 : \
(curve) == PSA_ECC_CURVE_SECT233R1 ? 233 : \
(curve) == PSA_ECC_CURVE_SECT239K1 ? 239 : \
(curve) == PSA_ECC_CURVE_SECT283K1 ? 283 : \
(curve) == PSA_ECC_CURVE_SECT283R1 ? 283 : \
(curve) == PSA_ECC_CURVE_SECT409K1 ? 409 : \
(curve) == PSA_ECC_CURVE_SECT409R1 ? 409 : \
(curve) == PSA_ECC_CURVE_SECT571K1 ? 571 : \
(curve) == PSA_ECC_CURVE_SECT571R1 ? 571 : \
(curve) == PSA_ECC_CURVE_SECP160K1 ? 160 : \
(curve) == PSA_ECC_CURVE_SECP160R1 ? 160 : \
(curve) == PSA_ECC_CURVE_SECP160R2 ? 160 : \
(curve) == PSA_ECC_CURVE_SECP192K1 ? 192 : \
(curve) == PSA_ECC_CURVE_SECP192R1 ? 192 : \
(curve) == PSA_ECC_CURVE_SECP224K1 ? 224 : \
(curve) == PSA_ECC_CURVE_SECP224R1 ? 224 : \
(curve) == PSA_ECC_CURVE_SECP256K1 ? 256 : \
(curve) == PSA_ECC_CURVE_SECP256R1 ? 256 : \
(curve) == PSA_ECC_CURVE_SECP384R1 ? 384 : \
(curve) == PSA_ECC_CURVE_SECP521R1 ? 521 : \
(curve) == PSA_ECC_CURVE_BRAINPOOL_P256R1 ? 256 : \
(curve) == PSA_ECC_CURVE_BRAINPOOL_P384R1 ? 384 : \
(curve) == PSA_ECC_CURVE_BRAINPOOL_P512R1 ? 512 : \
(curve) == PSA_ECC_CURVE_CURVE25519 ? 255 : \
(curve) == PSA_ECC_CURVE_CURVE448 ? 448 : \
0)

/** \def PSA_ALG_TLS12_PSK_TO_MS_MAX_PSK_LEN
*
* This macro returns the maximum length of the PSK supported
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3 changes: 3 additions & 0 deletions library/psa_crypto.c
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Expand Up @@ -621,6 +621,9 @@ static psa_status_t psa_import_ec_private_key( psa_ecc_curve_t curve,
mbedtls_ecp_keypair *ecp = NULL;
mbedtls_ecp_group_id grp_id = mbedtls_ecc_group_of_psa( curve );

if( PSA_BITS_TO_BYTES( PSA_ECC_CURVE_BITS( curve ) ) != data_length )
return( PSA_ERROR_INVALID_ARGUMENT );
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Do we support curves with bit sizes not even multiples of 8? Would we zero-pad within the first or last byte? I looked at export key format, but didn't see the answer, although we do mention endianness.

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Yes (P521). It's zero-padded in the most significant byte, which you know because the spec tells you you have to represent the number in a given number of bits. You know which byte that is because you're told the endianness.


*p_ecp = NULL;
ecp = mbedtls_calloc( 1, sizeof( mbedtls_ecp_keypair ) );
if( ecp == NULL )
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4 changes: 4 additions & 0 deletions tests/suites/test_suite_psa_crypto.data
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Expand Up @@ -243,6 +243,10 @@ PSA import EC keypair: DER format
depends_on:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
import:"3077020101042049c9a8c18c4b885638c431cf1df1c994131609b580d4fd43a0cab17db2f13eeea00a06082a8648ce3d030107a144034200047772656f814b399279d5e1f1781fac6f099a3c5ca1b0e35351834b08b65e0b572590cdaf8f769361bcf34acfc11e5e074e8426bdde04be6e653945449617de45":PSA_KEY_TYPE_ECC_KEYPAIR(PSA_ECC_CURVE_SECP256R1):0:PSA_ERROR_INVALID_ARGUMENT

PSA import EC keypair: too short
depends_on:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
import:"0123456789abcdef0123456789abcdef":PSA_KEY_TYPE_ECC_KEYPAIR(PSA_ECC_CURVE_SECP256R1):0:PSA_ERROR_INVALID_ARGUMENT

PSA import EC keypair: public key
depends_on:MBEDTLS_PK_PARSE_C:MBEDTLS_ECP_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
import:"04dea5e45d0ea37fc566232a508f4ad20ea13d47e4bf5fa4d54a57a0ba012042087097496efc583fed8b24a5b9be9a51de063f5a00a8b698a16fd7f29b5485f320":PSA_KEY_TYPE_ECC_KEYPAIR(PSA_ECC_CURVE_SECP256R1):0:PSA_ERROR_INVALID_ARGUMENT
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4 changes: 1 addition & 3 deletions tests/suites/test_suite_psa_crypto_metadata.function
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Expand Up @@ -451,9 +451,7 @@ void ecc_key_types( int curve_arg, int curve_bits_arg )
TEST_EQUAL( PSA_KEY_TYPE_GET_CURVE( public_type ), curve );
TEST_EQUAL( PSA_KEY_TYPE_GET_CURVE( pair_type ), curve );

/* Validate that the bit size is less than the maximum ECC bit size
* in this implementation. There's no parameter that should be equal
* to curve_bits and can be validated without creating a key. */
TEST_EQUAL( curve_bits, PSA_ECC_CURVE_BITS( curve ) );
TEST_ASSERT( curve_bits <= PSA_VENDOR_ECC_MAX_CURVE_BITS );
}
/* END_CASE */