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Support wildcard hash in signature policies #15

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Merged
merged 5 commits into from
Jan 28, 2019
Merged

Support wildcard hash in signature policies #15

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d35b489
New macro PSA_ALG_IS_HASH_AND_SIGN
gilles-peskine-arm Jan 14, 2019
30f77cd
Add a hash wildcard value for hash-and-sign algorithm
gilles-peskine-arm Jan 14, 2019
870f5dc
Add missing test dependency
gilles-peskine-arm Jan 23, 2019
eb2d4b9
Test that HASH_ANY is not meaningful for OAEP
gilles-peskine-arm Jan 24, 2019
763fb9a
Improve the description of PSA_ALG_ANY_HASH
gilles-peskine-arm Jan 28, 2019
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20 changes: 18 additions & 2 deletions include/psa/crypto_values.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1046,6 +1046,23 @@
#define PSA_ALG_IS_RANDOMIZED_ECDSA(alg) \
(PSA_ALG_IS_ECDSA(alg) && !PSA_ALG_ECDSA_IS_DETERMINISTIC(alg))

/** Whether the specified algorithm is a hash-and-sign algorithm.
*
* Hash-and-sign algorithms are public-key signature algorithms structured
* in two parts: first the calculation of a hash in a way that does not
* depend on the key, then the calculation of a signature from the
* hash value and the key.
*
* \param alg An algorithm identifier (value of type #psa_algorithm_t).
*
* \return 1 if \p alg is a hash-and-sign algorithm, 0 otherwise.
* This macro may return either 0 or 1 if \p alg is not a supported
* algorithm identifier.
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@Patater Patater Jan 14, 2019

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Could we decide if this is going to return a 0 or a 1 now, when alg is not a supported algorithm identifier, instead of leaving it up to implementations? How about always 0 in such cases? I see advantage for applications in making the behavior predictable, but does the advantage of flexibility for implementations outweigh this?

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@gilles-peskine-arm gilles-peskine-arm Jan 14, 2019

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This is a macro which returns a constant expression so that it can be used to calculate static buffer sizes in applications that don't need runtime algorithm agility. So it must be implemented based on some simple bit patterns, not based on what some cryptoprocessor has to say about the algorithm. In particular, this macro cannot determine whether an algorithm is supported, so it can't return 0 for all unsupported algorithms. There is no clear semantic rule to choose between 0 and 1 for an unsupported algorithm, hence the specification leaves the result undefined in that case.

This consideration applies to all the PSA_ALG_IS_xxx macros.

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@Patater Patater Jan 14, 2019

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Shucks

*/
#define PSA_ALG_IS_HASH_AND_SIGN(alg) \
(PSA_ALG_IS_RSA_PSS(alg) || PSA_ALG_IS_RSA_PKCS1V15_SIGN(alg) || \
PSA_ALG_IS_DSA(alg) || PSA_ALG_IS_ECDSA(alg))

/** Get the hash used by a hash-and-sign signature algorithm.
*
* A hash-and-sign algorithm is a signature algorithm which is
Expand All @@ -1065,8 +1082,7 @@
* if it is not supported by the implementation.
*/
#define PSA_ALG_SIGN_GET_HASH(alg) \
(PSA_ALG_IS_RSA_PSS(alg) || PSA_ALG_IS_RSA_PKCS1V15_SIGN(alg) || \
PSA_ALG_IS_DSA(alg) || PSA_ALG_IS_ECDSA(alg) ? \
(PSA_ALG_IS_HASH_AND_SIGN(alg) ? \
((alg) & PSA_ALG_HASH_MASK) == 0 ? /*"raw" algorithm*/ 0 : \
((alg) & PSA_ALG_HASH_MASK) | PSA_ALG_CATEGORY_HASH : \
0)
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16 changes: 8 additions & 8 deletions tests/suites/test_suite_psa_crypto_metadata.data
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Expand Up @@ -200,35 +200,35 @@ aead_algorithm:PSA_ALG_GCM:0:16

Asymmetric signature: RSA PKCS#1 v1.5 raw
depends_on:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15
asymmetric_signature_algorithm:PSA_ALG_RSA_PKCS1V15_SIGN_RAW:ALG_IS_RSA_PKCS1V15_SIGN
asymmetric_signature_algorithm:PSA_ALG_RSA_PKCS1V15_SIGN_RAW:ALG_IS_RSA_PKCS1V15_SIGN | ALG_IS_HASH_AND_SIGN

Asymmetric signature: RSA PKCS#1 v1.5 SHA-256
depends_on:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15:MBEDTLS_SHA256_C
asymmetric_signature_algorithm:PSA_ALG_RSA_PKCS1V15_SIGN( PSA_ALG_SHA_256 ):ALG_IS_RSA_PKCS1V15_SIGN
asymmetric_signature_algorithm:PSA_ALG_RSA_PKCS1V15_SIGN( PSA_ALG_SHA_256 ):ALG_IS_RSA_PKCS1V15_SIGN | ALG_IS_HASH_AND_SIGN

Asymmetric signature: RSA PSS SHA-256
depends_on:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V21:MBEDTLS_SHA256_C
asymmetric_signature_algorithm:PSA_ALG_RSA_PSS( PSA_ALG_SHA_256 ):ALG_IS_RSA_PSS
asymmetric_signature_algorithm:PSA_ALG_RSA_PSS( PSA_ALG_SHA_256 ):ALG_IS_RSA_PSS | ALG_IS_HASH_AND_SIGN

Asymmetric signature: SHA-256 + randomized DSA SHA-256 using SHA-256
depends_on:MBEDTLS_DSA_C:MBEDTLS_SHA256_C
asymmetric_signature_algorithm:PSA_ALG_DSA( PSA_ALG_SHA_256 ):ALG_IS_DSA | ALG_IS_RANDOMIZED_DSA
asymmetric_signature_algorithm:PSA_ALG_DSA( PSA_ALG_SHA_256 ):ALG_IS_DSA | ALG_IS_RANDOMIZED_DSA | ALG_IS_HASH_AND_SIGN

Asymmetric signature: SHA-256 + deterministic DSA using SHA-256
depends_on:MBEDTLS_DSA_C:MBEDTLS_SHA256_C:MBEDTLS_DSA_DETERMINISTIC
asymmetric_signature_algorithm:PSA_ALG_DETERMINISTIC_DSA( PSA_ALG_SHA_256 ):ALG_IS_DSA | ALG_IS_DETERMINISTIC_DSA | ALG_DSA_IS_DETERMINISTIC
asymmetric_signature_algorithm:PSA_ALG_DETERMINISTIC_DSA( PSA_ALG_SHA_256 ):ALG_IS_DSA | ALG_IS_DETERMINISTIC_DSA | ALG_DSA_IS_DETERMINISTIC | ALG_IS_HASH_AND_SIGN

Asymmetric signature: randomized ECDSA (no hashing)
depends_on:MBEDTLS_ECDSA_C
asymmetric_signature_algorithm:PSA_ALG_ECDSA_ANY:ALG_IS_ECDSA | ALG_IS_RANDOMIZED_ECDSA
asymmetric_signature_algorithm:PSA_ALG_ECDSA_ANY:ALG_IS_ECDSA | ALG_IS_RANDOMIZED_ECDSA | ALG_IS_HASH_AND_SIGN

Asymmetric signature: SHA-256 + randomized ECDSA
depends_on:MBEDTLS_ECDSA_C:MBEDTLS_SHA256_C
asymmetric_signature_algorithm:PSA_ALG_ECDSA( PSA_ALG_SHA_256 ):ALG_IS_ECDSA | ALG_IS_RANDOMIZED_ECDSA
asymmetric_signature_algorithm:PSA_ALG_ECDSA( PSA_ALG_SHA_256 ):ALG_IS_ECDSA | ALG_IS_RANDOMIZED_ECDSA | ALG_IS_HASH_AND_SIGN

Asymmetric signature: SHA-256 + deterministic DSA using SHA-256
depends_on:MBEDTLS_ECDSA_C:MBEDTLS_ECDSA_DETERMINISTIC:MBEDTLS_SHA256_C
asymmetric_signature_algorithm:PSA_ALG_DETERMINISTIC_ECDSA( PSA_ALG_SHA_256 ):ALG_IS_ECDSA | ALG_IS_DETERMINISTIC_ECDSA | ALG_ECDSA_IS_DETERMINISTIC
asymmetric_signature_algorithm:PSA_ALG_DETERMINISTIC_ECDSA( PSA_ALG_SHA_256 ):ALG_IS_ECDSA | ALG_IS_DETERMINISTIC_ECDSA | ALG_ECDSA_IS_DETERMINISTIC | ALG_IS_HASH_AND_SIGN

Asymmetric encryption: RSA PKCS#1 v1.5
depends_on:MBEDTLS_RSA_C:MBEDTLS_PKCS1_V15
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10 changes: 6 additions & 4 deletions tests/suites/test_suite_psa_crypto_metadata.function
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Original file line number Diff line number Diff line change
Expand Up @@ -29,10 +29,11 @@
#define ALG_ECDSA_IS_DETERMINISTIC ( 1u << 11 )
#define ALG_IS_DETERMINISTIC_ECDSA ( 1u << 12 )
#define ALG_IS_RANDOMIZED_ECDSA ( 1u << 13 )
#define ALG_IS_RSA_OAEP ( 1u << 14 )
#define ALG_IS_HKDF ( 1u << 15 )
#define ALG_IS_FFDH ( 1u << 16 )
#define ALG_IS_ECDH ( 1u << 17 )
#define ALG_IS_HASH_AND_SIGN ( 1u << 14 )
#define ALG_IS_RSA_OAEP ( 1u << 15 )
#define ALG_IS_HKDF ( 1u << 16 )
#define ALG_IS_FFDH ( 1u << 17 )
#define ALG_IS_ECDH ( 1u << 18 )

/* Flags for key type classification macros. There is a flag for every
* key type classification macro PSA_KEY_TYPE_IS_xxx except for some that
Expand Down Expand Up @@ -67,6 +68,7 @@ void algorithm_classification( psa_algorithm_t alg, unsigned flags )
TEST_CLASSIFICATION_MACRO( ALG_ECDSA_IS_DETERMINISTIC, alg, flags );
TEST_CLASSIFICATION_MACRO( ALG_IS_DETERMINISTIC_ECDSA, alg, flags );
TEST_CLASSIFICATION_MACRO( ALG_IS_RANDOMIZED_ECDSA, alg, flags );
TEST_CLASSIFICATION_MACRO( ALG_IS_HASH_AND_SIGN, alg, flags );
TEST_CLASSIFICATION_MACRO( ALG_IS_RSA_OAEP, alg, flags );
TEST_CLASSIFICATION_MACRO( ALG_IS_HKDF, alg, flags );
exit: ;
Expand Down