From 32611243d4973050759e4821f420b63171b2fc8f Mon Sep 17 00:00:00 2001 From: Gilles Peskine Date: Sat, 19 Mar 2022 12:09:13 +0100 Subject: [PATCH] Don't exercise OAEP with small key and large hash RSA-OAEP requires the key to be larger than a function of the hash size. Ideally such combinations would be detected as a key/algorithm incompatibility. However key/algorithm compatibility is currently tested between the key type and the algorithm without considering the key size, and this is inconvenient to change. So as a workaround, dispense OAEP-with-too-small-hash from exercising, without including it in the automatic operation-failure test generation. Signed-off-by: Gilles Peskine --- scripts/mbedtls_dev/crypto_knowledge.py | 33 +++++++++++++------ tests/scripts/generate_psa_tests.py | 29 +++++++++++++++- ...st_suite_psa_crypto_storage_format.v0.data | 4 +-- 3 files changed, 53 insertions(+), 13 deletions(-) diff --git a/scripts/mbedtls_dev/crypto_knowledge.py b/scripts/mbedtls_dev/crypto_knowledge.py index b8ca621be..83470fd97 100644 --- a/scripts/mbedtls_dev/crypto_knowledge.py +++ b/scripts/mbedtls_dev/crypto_knowledge.py @@ -211,7 +211,7 @@ class KeyType: This function does not currently handle key derivation or PAKE. """ - #pylint: disable=too-many-return-statements + #pylint: disable=too-many-branches,too-many-return-statements if alg.is_wildcard: return False if alg.is_invalid_truncation(): @@ -423,28 +423,41 @@ class Algorithm: """ return short_expression(self.expression, level=level) + HASH_LENGTH = { + 'PSA_ALG_MD5': 16, + 'PSA_ALG_SHA_1': 20, + } + HASH_LENGTH_BITS_RE = re.compile(r'([0-9]+)\Z') + @classmethod + def hash_length(cls, alg: str) -> int: + """The length of the given hash algorithm, in bytes.""" + if alg in cls.HASH_LENGTH: + return cls.HASH_LENGTH[alg] + m = cls.HASH_LENGTH_BITS_RE.search(alg) + if m: + return int(m.group(1)) // 8 + raise ValueError('Unknown hash length for ' + alg) + PERMITTED_TAG_LENGTHS = { 'PSA_ALG_CCM': frozenset([4, 6, 8, 10, 12, 14, 16]), 'PSA_ALG_CHACHA20_POLY1305': frozenset([16]), 'PSA_ALG_GCM': frozenset([4, 8, 12, 13, 14, 15, 16]), } MAC_LENGTH = { - 'PSA_ALG_CBC_MAC': 16, - 'PSA_ALG_CMAC': 16, - 'PSA_ALG_HMAC(PSA_ALG_MD5)': 16, - 'PSA_ALG_HMAC(PSA_ALG_SHA_1)': 20, + 'PSA_ALG_CBC_MAC': 16, # actually the block cipher length + 'PSA_ALG_CMAC': 16, # actually the block cipher length } - HMAC_WITH_NOMINAL_LENGTH_RE = re.compile(r'PSA_ALG_HMAC\(\w+([0-9])+\)\Z') + HMAC_RE = re.compile(r'PSA_ALG_HMAC\((.*)\)\Z') @classmethod - def mac_or_tag_length(cls, base: str) -> FrozenSet[int]: + def mac_or_tag_lengths(cls, base: str) -> FrozenSet[int]: """Return the set of permitted lengths for the given MAC or AEAD tag.""" if base in cls.PERMITTED_TAG_LENGTHS: return cls.PERMITTED_TAG_LENGTHS[base] max_length = cls.MAC_LENGTH.get(base, None) if max_length is None: - m = cls.HMAC_WITH_NOMINAL_LENGTH_RE.match(base) + m = cls.HMAC_RE.match(base) if m: - max_length = int(m.group(1)) // 8 + max_length = cls.hash_length(m.group(1)) if max_length is None: raise ValueError('Unknown permitted lengths for ' + base) return frozenset(range(4, max_length + 1)) @@ -464,7 +477,7 @@ class Algorithm: if m: base = m.group('base') to_length = int(m.group('length'), 0) - permitted_lengths = self.mac_or_tag_length(base) + permitted_lengths = self.mac_or_tag_lengths(base) if to_length not in permitted_lengths: return True return False diff --git a/tests/scripts/generate_psa_tests.py b/tests/scripts/generate_psa_tests.py index dd5c4177d..548959006 100755 --- a/tests/scripts/generate_psa_tests.py +++ b/tests/scripts/generate_psa_tests.py @@ -516,6 +516,32 @@ class StorageFormat: self.version = version #type: int self.forward = forward #type: bool + RSA_OAEP_RE = re.compile(r'PSA_ALG_RSA_OAEP\((.*)\)\Z') + @classmethod + def valid_key_size_for_algorithm( + cls, + key_type: psa_storage.Expr, bits: int, + alg: psa_storage.Expr + ) -> bool: + """Whether the given key type and size are valid for the algorithm. + + Normally only the type and algorithm matter for compatibility, and + this is handled in crypto_knowledge.KeyType.can_do(). This function + exists to detect exceptional cases. Exceptional cases detected here + are not tested in OpFail and should therefore have manually written + test cases. + """ + #pylint: disable=unused-argument + # OAEP requires room for two hashes plus wrapping + m = cls.RSA_OAEP_RE.match(alg.string) + if m: + hash_alg = m.group(1) + hash_length = crypto_knowledge.Algorithm.hash_length(hash_alg) + key_length = (bits + 7) // 8 + # Leave enough room for at least one byte of plaintext + return key_length > 2 * hash_length + 2 + return True + def make_test_case(self, key: StorageTestData) -> test_case.TestCase: """Construct a storage format test case for the given key. @@ -544,7 +570,8 @@ class StorageFormat: # encodings of the attributes. # Raw data keys have no useful exercise anyway so there is no # loss of test coverage. - if key.type.string != 'PSA_KEY_TYPE_RAW_DATA': + if key.type.string != 'PSA_KEY_TYPE_RAW_DATA' and \ + self.valid_key_size_for_algorithm(key.type, key.bits, key.alg): flags.append('TEST_FLAG_EXERCISE') if 'READ_ONLY' in key.lifetime.string: flags.append('TEST_FLAG_READ_ONLY') diff --git a/tests/suites/test_suite_psa_crypto_storage_format.v0.data b/tests/suites/test_suite_psa_crypto_storage_format.v0.data index bd7b9b433..f1f7c5427 100644 --- a/tests/suites/test_suite_psa_crypto_storage_format.v0.data +++ b/tests/suites/test_suite_psa_crypto_storage_format.v0.data @@ -7218,7 +7218,7 @@ key_storage_read:0x0001:PSA_KEY_TYPE_RSA_KEY_PAIR:1024:PSA_KEY_USAGE_DECRYPT | P read type: RSA_PAIR 1024-bit, RSA_OAEP(SHA_512) depends_on:PSA_WANT_ALG_RSA_OAEP:PSA_WANT_ALG_SHA_512:PSA_WANT_KEY_TYPE_RSA_KEY_PAIR -key_storage_read:0x0001:PSA_KEY_TYPE_RSA_KEY_PAIR:1024:PSA_KEY_USAGE_DECRYPT | PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_EXPORT:PSA_ALG_RSA_OAEP(PSA_ALG_SHA_512):0x0000:"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":"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":TEST_FLAG_EXERCISE +key_storage_read:0x0001:PSA_KEY_TYPE_RSA_KEY_PAIR:1024:PSA_KEY_USAGE_DECRYPT | PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_EXPORT:PSA_ALG_RSA_OAEP(PSA_ALG_SHA_512):0x0000:"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":"505341004b455900000000000100000001700004010300000b03000700000000620200003082025e02010002818100af057d396ee84fb75fdbb5c2b13c7fe5a654aa8aa2470b541ee1feb0b12d25c79711531249e1129628042dbbb6c120d1443524ef4c0e6e1d8956eeb2077af12349ddeee54483bc06c2c61948cd02b202e796aebd94d3a7cbf859c2c1819c324cb82b9cd34ede263a2abffe4733f077869e8660f7d6834da53d690ef7985f6bc3020301000102818100874bf0ffc2f2a71d14671ddd0171c954d7fdbf50281e4f6d99ea0e1ebcf82faa58e7b595ffb293d1abe17f110b37c48cc0f36c37e84d876621d327f64bbe08457d3ec4098ba2fa0a319fba411c2841ed7be83196a8cdf9daa5d00694bc335fc4c32217fe0488bce9cb7202e59468b1ead119000477db2ca797fac19eda3f58c1024100e2ab760841bb9d30a81d222de1eb7381d82214407f1b975cbbfe4e1a9467fd98adbd78f607836ca5be1928b9d160d97fd45c12d6b52e2c9871a174c66b488113024100c5ab27602159ae7d6f20c3c2ee851e46dc112e689e28d5fcbbf990a99ef8a90b8bb44fd36467e7fc1789ceb663abda338652c3c73f111774902e840565927091024100b6cdbd354f7df579a63b48b3643e353b84898777b48b15f94e0bfc0567a6ae5911d57ad6409cf7647bf96264e9bd87eb95e263b7110b9a1f9f94acced0fafa4d024071195eec37e8d257decfc672b07ae639f10cbb9b0c739d0c809968d644a94e3fd6ed9287077a14583f379058f76a8aecd43c62dc8c0f41766650d725275ac4a1024100bb32d133edc2e048d463388b7be9cb4be29f4b6250be603e70e3647501c97ddde20a4e71be95fd5e71784e25aca4baf25be5738aae59bbfe1c997781447a2b24":0 read type: RSA_PAIR 1024-bit, RSA_PKCS1V15_CRYPT depends_on:PSA_WANT_ALG_RSA_PKCS1V15_CRYPT:PSA_WANT_KEY_TYPE_RSA_KEY_PAIR @@ -7530,7 +7530,7 @@ key_storage_read:0x0001:PSA_KEY_TYPE_RSA_PUBLIC_KEY:1024:PSA_KEY_USAGE_ENCRYPT | read type: RSA_PUB 1024-bit, RSA_OAEP(SHA_512) depends_on:PSA_WANT_ALG_RSA_OAEP:PSA_WANT_ALG_SHA_512:PSA_WANT_KEY_TYPE_RSA_PUBLIC_KEY -key_storage_read:0x0001:PSA_KEY_TYPE_RSA_PUBLIC_KEY:1024:PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_EXPORT:PSA_ALG_RSA_OAEP(PSA_ALG_SHA_512):0x0000:"30818902818100af057d396ee84fb75fdbb5c2b13c7fe5a654aa8aa2470b541ee1feb0b12d25c79711531249e1129628042dbbb6c120d1443524ef4c0e6e1d8956eeb2077af12349ddeee54483bc06c2c61948cd02b202e796aebd94d3a7cbf859c2c1819c324cb82b9cd34ede263a2abffe4733f077869e8660f7d6834da53d690ef7985f6bc30203010001":"505341004b455900000000000100000001400004010100000b030007000000008c00000030818902818100af057d396ee84fb75fdbb5c2b13c7fe5a654aa8aa2470b541ee1feb0b12d25c79711531249e1129628042dbbb6c120d1443524ef4c0e6e1d8956eeb2077af12349ddeee54483bc06c2c61948cd02b202e796aebd94d3a7cbf859c2c1819c324cb82b9cd34ede263a2abffe4733f077869e8660f7d6834da53d690ef7985f6bc30203010001":TEST_FLAG_EXERCISE +key_storage_read:0x0001:PSA_KEY_TYPE_RSA_PUBLIC_KEY:1024:PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_EXPORT:PSA_ALG_RSA_OAEP(PSA_ALG_SHA_512):0x0000:"30818902818100af057d396ee84fb75fdbb5c2b13c7fe5a654aa8aa2470b541ee1feb0b12d25c79711531249e1129628042dbbb6c120d1443524ef4c0e6e1d8956eeb2077af12349ddeee54483bc06c2c61948cd02b202e796aebd94d3a7cbf859c2c1819c324cb82b9cd34ede263a2abffe4733f077869e8660f7d6834da53d690ef7985f6bc30203010001":"505341004b455900000000000100000001400004010100000b030007000000008c00000030818902818100af057d396ee84fb75fdbb5c2b13c7fe5a654aa8aa2470b541ee1feb0b12d25c79711531249e1129628042dbbb6c120d1443524ef4c0e6e1d8956eeb2077af12349ddeee54483bc06c2c61948cd02b202e796aebd94d3a7cbf859c2c1819c324cb82b9cd34ede263a2abffe4733f077869e8660f7d6834da53d690ef7985f6bc30203010001":0 read type: RSA_PUB 1024-bit, RSA_PKCS1V15_CRYPT depends_on:PSA_WANT_ALG_RSA_PKCS1V15_CRYPT:PSA_WANT_KEY_TYPE_RSA_PUBLIC_KEY