add RSA PSS verification support
diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index a68bc08..7358280 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -27,6 +27,9 @@
from cryptography.hazmat.bindings.openssl.binding import Binding
from cryptography.hazmat.primitives import interfaces, hashes
from cryptography.hazmat.primitives.asymmetric import rsa
+from cryptography.hazmat.primitives.asymmetric.padding import (
+ PKCS1v15, PSS, MGF1
+)
from cryptography.hazmat.primitives.ciphers.algorithms import (
AES, Blowfish, Camellia, CAST5, TripleDES, ARC4, IDEA
)
@@ -377,6 +380,12 @@
return _RSAVerificationContext(self, public_key, signature, padding,
algorithm)
+ def mgf1_hash_supported(self, algorithm):
+ if self._lib.Cryptography_HAS_MGF1_MD:
+ return self.hash_supported(algorithm)
+ else:
+ return isinstance(algorithm, hashes.SHA1)
+
class GetCipherByName(object):
def __init__(self, fmt):
@@ -760,12 +769,26 @@
raise TypeError(
"Expected provider of interfaces.AsymmetricPadding")
- if padding.name == "EMSA-PKCS1-v1_5":
+ if isinstance(padding, PKCS1v15):
if self._backend._lib.Cryptography_HAS_PKEY_CTX:
self._verify_method = self._verify_pkey_ctx
self._padding_enum = self._backend._lib.RSA_PKCS1_PADDING
else:
self._verify_method = self._verify_pkcs1
+ elif isinstance(padding, PSS):
+ if not isinstance(padding.mgf, MGF1):
+ raise TypeError("Only MGF1 is supported by this backend")
+
+ if (not isinstance(padding.mgf._algorithm, hashes.SHA1) and
+ not self._backend._lib.Cryptography_HAS_MGF1_MD):
+ raise UnsupportedHash("This backend only supports MGF1 with "
+ "SHA1 when OpenSSL is not 1.0.1+")
+
+ if self._backend._lib.Cryptography_HAS_PKEY_CTX:
+ self._verify_method = self._verify_pkey_ctx
+ self._padding_enum = self._backend._lib.RSA_PKCS1_PSS_PADDING
+ else:
+ self._verify_method = self._verify_pss
else:
raise UnsupportedPadding
@@ -806,6 +829,20 @@
res = self._backend._lib.EVP_PKEY_CTX_set_rsa_padding(
pkey_ctx, self._padding_enum)
assert res > 0
+ if isinstance(self._padding, PSS):
+ res = self._backend._lib.EVP_PKEY_CTX_set_rsa_pss_saltlen(
+ pkey_ctx, self._get_salt_length())
+ assert res > 0
+ if self._backend._lib.Cryptography_HAS_MGF1_MD:
+ # MGF1 MD is configurable in OpenSSL 1.0.1+
+ mgf1_md = self._backend._lib.EVP_get_digestbyname(
+ self._padding.mgf._algorithm.name.encode("ascii"))
+ assert mgf1_md != self._backend._ffi.NULL
+ res = self._backend._lib.EVP_PKEY_CTX_set_rsa_mgf1_md(
+ pkey_ctx, mgf1_md
+ )
+ assert res > 0
+
data_to_verify = self._hash_ctx.finalize()
self._hash_ctx = None
res = self._backend._lib.EVP_PKEY_verify(
@@ -842,5 +879,39 @@
assert errors
raise InvalidSignature
+ def _verify_pss(self, rsa_cdata, evp_pkey, evp_md):
+ pkey_size = self._backend._lib.EVP_PKEY_size(evp_pkey)
+ assert pkey_size > 0
+ buf = self._backend._ffi.new("unsigned char[]", pkey_size)
+ res = self._backend._lib.RSA_public_decrypt(
+ len(self._signature),
+ self._signature,
+ buf,
+ rsa_cdata,
+ self._backend._lib.RSA_NO_PADDING
+ )
+ if res != pkey_size:
+ assert self._backend._consume_errors()
+ raise InvalidSignature
+
+ data_to_verify = self._hash_ctx.finalize()
+ self._hash_ctx = None
+ res = self._backend._lib.RSA_verify_PKCS1_PSS(
+ rsa_cdata,
+ data_to_verify,
+ evp_md,
+ buf,
+ self._get_salt_length()
+ )
+ if res != 1:
+ assert self._backend._consume_errors()
+ raise InvalidSignature
+
+ def _get_salt_length(self):
+ if self._padding.mgf._salt_length is MGF1.MAX_LENGTH:
+ return -2
+ else:
+ return self._padding.mgf._salt_length
+
backend = Backend()
diff --git a/cryptography/hazmat/primitives/asymmetric/padding.py b/cryptography/hazmat/primitives/asymmetric/padding.py
index 46e00b8..a812980 100644
--- a/cryptography/hazmat/primitives/asymmetric/padding.py
+++ b/cryptography/hazmat/primitives/asymmetric/padding.py
@@ -24,6 +24,14 @@
name = "EMSA-PKCS1-v1_5"
+@utils.register_interface(interfaces.AsymmetricPadding)
+class PSS(object):
+ name = "EMSA-PSS"
+
+ def __init__(self, mgf):
+ self.mgf = mgf
+
+
class MGF1(object):
MAX_LENGTH = object()
diff --git a/docs/hazmat/primitives/asymmetric/padding.rst b/docs/hazmat/primitives/asymmetric/padding.rst
index 8a03432..aa48b31 100644
--- a/docs/hazmat/primitives/asymmetric/padding.rst
+++ b/docs/hazmat/primitives/asymmetric/padding.rst
@@ -17,6 +17,18 @@
PKCS1 v1.5 (also known as simply PKCS1) is a simple padding scheme
developed for use with RSA keys. It is defined in :rfc:`3447`.
+.. class:: PSS(mgf)
+
+ .. versionadded:: 0.3
+
+ PSS (Probabilistic Signature Scheme) is a signature scheme defined in
+ :rfc:`3447`. It is more complex than PKCS1 but possesses a `security proof`_.
+ This is the recommended padding algorithm for RSA.
+
+ :param mgf: A mask generation function object. At this time the only
+ supported MGF is :class:`MGF1`.
+
+
Mask Generation Functions
~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -41,3 +53,4 @@
.. _`Padding is critical`: http://rdist.root.org/2009/10/06/why-rsa-encryption-padding-is-critical/
+.. _`security proof`: http://eprint.iacr.org/2001/062.pdf
diff --git a/tests/hazmat/primitives/test_rsa.py b/tests/hazmat/primitives/test_rsa.py
index 0e88bb7..8e9637f 100644
--- a/tests/hazmat/primitives/test_rsa.py
+++ b/tests/hazmat/primitives/test_rsa.py
@@ -25,7 +25,10 @@
from cryptography.hazmat.primitives import hashes, interfaces
from cryptography.hazmat.primitives.asymmetric import rsa, padding
-from ...utils import load_pkcs1_vectors, load_vectors_from_file
+from .utils import generate_rsa_pss_test
+from ...utils import (
+ load_pkcs1_vectors, load_vectors_from_file, load_rsa_nist_vectors
+)
@utils.register_interface(interfaces.AsymmetricPadding)
@@ -33,6 +36,10 @@
name = "UNSUPPORTED-PADDING"
+class DummyMGF(object):
+ pass
+
+
def _modinv(e, m):
"""
Modular Multiplicative Inverse. Returns x such that: (x*e) mod m == 1
@@ -530,6 +537,122 @@
with pytest.raises(exceptions.InvalidSignature):
verifier.verify()
+ @pytest.mark.parametrize(
+ "pkcs1_example",
+ _flatten_pkcs1_examples(load_vectors_from_file(
+ os.path.join(
+ "asymmetric", "RSA", "pkcs-1v2-1d2-vec", "pss-vect.txt"),
+ load_pkcs1_vectors
+ ))
+ )
+ def test_pss_verification(self, pkcs1_example, backend):
+ private, public, example = pkcs1_example
+ public_key = rsa.RSAPublicKey(
+ public_exponent=public["public_exponent"],
+ modulus=public["modulus"]
+ )
+ verifier = public_key.verifier(
+ binascii.unhexlify(example["signature"]),
+ padding.PSS(
+ mgf=padding.MGF1(
+ algorithm=hashes.SHA1(),
+ salt_length=padding.MGF1.MAX_LENGTH
+ )
+ ),
+ hashes.SHA1(),
+ backend
+ )
+ verifier.update(binascii.unhexlify(example["message"]))
+ verifier.verify()
+
+ def test_invalid_pss_signature_wrong_data(self, backend):
+ public_key = rsa.RSAPublicKey(
+ modulus=int(
+ b"dffc2137d5e810cde9e4b4612f5796447218bab913b3fa98bdf7982e4fa6"
+ b"ec4d6653ef2b29fb1642b095befcbea6decc178fb4bed243d3c3592c6854"
+ b"6af2d3f3", 16
+ ),
+ public_exponent=65537
+ )
+ signature = binascii.unhexlify(
+ b"0e68c3649df91c5bc3665f96e157efa75b71934aaa514d91e94ca8418d100f45"
+ b"6f05288e58525f99666bab052adcffdf7186eb40f583bd38d98c97d3d524808b"
+ )
+ verifier = public_key.verifier(
+ signature,
+ padding.PSS(
+ mgf=padding.MGF1(
+ algorithm=hashes.SHA1(),
+ salt_length=padding.MGF1.MAX_LENGTH
+ )
+ ),
+ hashes.SHA1(),
+ backend
+ )
+ verifier.update(b"incorrect data")
+ with pytest.raises(exceptions.InvalidSignature):
+ verifier.verify()
+
+ def test_invalid_pss_signature_wrong_key(self, backend):
+ signature = binascii.unhexlify(
+ b"3a1880165014ba6eb53cc1449d13e5132ebcc0cfd9ade6d7a2494a0503bd0826"
+ b"f8a46c431e0d7be0ca3e453f8b2b009e2733764da7927cc6dbe7a021437a242e"
+ )
+ public_key = rsa.RSAPublicKey(
+ modulus=int(
+ b"381201f4905d67dfeb3dec131a0fbea773489227ec7a1448c3109189ac68"
+ b"5a95441be90866a14c4d2e139cd16db540ec6c7abab13ffff91443fd46a8"
+ b"960cbb7658ded26a5c95c86f6e40384e1c1239c63e541ba221191c4dd303"
+ b"231b42e33c6dbddf5ec9a746f09bf0c25d0f8d27f93ee0ae5c0d723348f4"
+ b"030d3581e13522e1", 16
+ ),
+ public_exponent=65537
+ )
+ verifier = public_key.verifier(
+ signature,
+ padding.PSS(
+ mgf=padding.MGF1(
+ algorithm=hashes.SHA1(),
+ salt_length=padding.MGF1.MAX_LENGTH
+ )
+ ),
+ hashes.SHA1(),
+ backend
+ )
+ verifier.update(b"sign me")
+ with pytest.raises(exceptions.InvalidSignature):
+ verifier.verify()
+
+ def test_invalid_pss_signature_data_too_large_for_modulus(self, backend):
+ signature = binascii.unhexlify(
+ b"cb43bde4f7ab89eb4a79c6e8dd67e0d1af60715da64429d90c716a490b799c29"
+ b"194cf8046509c6ed851052367a74e2e92d9b38947ed74332acb115a03fcc0222"
+ )
+ public_key = rsa.RSAPublicKey(
+ modulus=int(
+ b"381201f4905d67dfeb3dec131a0fbea773489227ec7a1448c3109189ac68"
+ b"5a95441be90866a14c4d2e139cd16db540ec6c7abab13ffff91443fd46a8"
+ b"960cbb7658ded26a5c95c86f6e40384e1c1239c63e541ba221191c4dd303"
+ b"231b42e33c6dbddf5ec9a746f09bf0c25d0f8d27f93ee0ae5c0d723348f4"
+ b"030d3581e13522", 16
+ ),
+ public_exponent=65537
+ )
+ verifier = public_key.verifier(
+ signature,
+ padding.PSS(
+ mgf=padding.MGF1(
+ algorithm=hashes.SHA1(),
+ salt_length=padding.MGF1.MAX_LENGTH
+ )
+ ),
+ hashes.SHA1(),
+ backend
+ )
+ verifier.update(b"sign me")
+ with pytest.raises(exceptions.InvalidSignature):
+ verifier.verify()
+
def test_use_after_finalize(self, backend):
private_key = rsa.RSAPrivateKey.generate(
public_exponent=65537,
@@ -583,6 +706,130 @@
public_key.verifier(
b"foo", padding.PKCS1v15(), hashes.SHA256(), pretend_backend)
+ def test_unsupported_pss_mgf(self, backend):
+ private_key = rsa.RSAPrivateKey.generate(
+ public_exponent=65537,
+ key_size=512,
+ backend=backend
+ )
+ public_key = private_key.public_key()
+ with pytest.raises(TypeError):
+ public_key.verifier(b"sig", padding.PSS(mgf=DummyMGF()),
+ hashes.SHA1(), backend)
+
+ def test_pss_verify_salt_length_too_long(self, backend):
+ signature = binascii.unhexlify(
+ b"8b9a3ae9fb3b64158f3476dd8d8a1f1425444e98940e0926378baa9944d219d8"
+ b"534c050ef6b19b1bdc6eb4da422e89161106a6f5b5cc16135b11eb6439b646bd"
+ )
+ public_key = rsa.RSAPublicKey(
+ modulus=int(
+ b"d309e4612809437548b747d7f9eb9cd3340f54fe42bb3f84a36933b0839c"
+ b"11b0c8b7f67e11f7252370161e31159c49c784d4bc41c42a78ce0f0b40a3"
+ b"ca8ffb91", 16
+ ),
+ public_exponent=65537
+ )
+ verifier = public_key.verifier(
+ signature,
+ padding.PSS(
+ mgf=padding.MGF1(
+ algorithm=hashes.SHA1(),
+ salt_length=1000000
+ )
+ ),
+ hashes.SHA1(),
+ backend
+ )
+ verifier.update(b"sign me")
+ with pytest.raises(exceptions.InvalidSignature):
+ verifier.verify()
+
+
+@pytest.mark.supported(
+ only_if=lambda backend: backend.mgf1_hash_supported(hashes.SHA1()),
+ skip_message="Does not support SHA1 with MGF1."
+)
+@pytest.mark.rsa
+class TestRSAPSSMGF1VerificationSHA1(object):
+ test_rsa_pss_mgf1_sha1 = generate_rsa_pss_test(
+ load_rsa_nist_vectors,
+ os.path.join("asymmetric", "RSA", "FIPS_186-2"),
+ [
+ "SigGenPSS_186-2.rsp",
+ "SigGenPSS_186-3.rsp",
+ ],
+ b"SHA1"
+ )
+
+
+@pytest.mark.supported(
+ only_if=lambda backend: backend.mgf1_hash_supported(hashes.SHA224()),
+ skip_message="Does not support SHA224 with MGF1."
+)
+@pytest.mark.rsa
+class TestRSAPSSMGF1VerificationSHA224(object):
+ test_rsa_pss_mgf1_sha224 = generate_rsa_pss_test(
+ load_rsa_nist_vectors,
+ os.path.join("asymmetric", "RSA", "FIPS_186-2"),
+ [
+ "SigGenPSS_186-2.rsp",
+ "SigGenPSS_186-3.rsp",
+ ],
+ b"SHA224"
+ )
+
+
+@pytest.mark.supported(
+ only_if=lambda backend: backend.mgf1_hash_supported(hashes.SHA256()),
+ skip_message="Does not support SHA256 with MGF1."
+)
+@pytest.mark.rsa
+class TestRSAPSSMGF1VerificationSHA256(object):
+ test_rsa_pss_mgf1_sha256 = generate_rsa_pss_test(
+ load_rsa_nist_vectors,
+ os.path.join("asymmetric", "RSA", "FIPS_186-2"),
+ [
+ "SigGenPSS_186-2.rsp",
+ "SigGenPSS_186-3.rsp",
+ ],
+ b"SHA256"
+ )
+
+
+@pytest.mark.supported(
+ only_if=lambda backend: backend.mgf1_hash_supported(hashes.SHA384()),
+ skip_message="Does not support SHA384 with MGF1."
+)
+@pytest.mark.rsa
+class TestRSAPSSMGF1VerificationSHA384(object):
+ test_rsa_pss_mgf1_sha384 = generate_rsa_pss_test(
+ load_rsa_nist_vectors,
+ os.path.join("asymmetric", "RSA", "FIPS_186-2"),
+ [
+ "SigGenPSS_186-2.rsp",
+ "SigGenPSS_186-3.rsp",
+ ],
+ b"SHA384"
+ )
+
+
+@pytest.mark.supported(
+ only_if=lambda backend: backend.mgf1_hash_supported(hashes.SHA512()),
+ skip_message="Does not support SHA512 with MGF1."
+)
+@pytest.mark.rsa
+class TestRSAPSSMGF1VerificationSHA512(object):
+ test_rsa_pss_mgf1_sha512 = generate_rsa_pss_test(
+ load_rsa_nist_vectors,
+ os.path.join("asymmetric", "RSA", "FIPS_186-2"),
+ [
+ "SigGenPSS_186-2.rsp",
+ "SigGenPSS_186-3.rsp",
+ ],
+ b"SHA512"
+ )
+
class TestMGF1(object):
def test_invalid_hash_algorithm(self):
diff --git a/tests/hazmat/primitives/utils.py b/tests/hazmat/primitives/utils.py
index f0a0031..38f6704 100644
--- a/tests/hazmat/primitives/utils.py
+++ b/tests/hazmat/primitives/utils.py
@@ -21,6 +21,7 @@
import pytest
from cryptography.hazmat.primitives import hashes, hmac
+from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
from cryptography.hazmat.primitives.ciphers import Cipher
from cryptography.hazmat.primitives.kdf.hkdf import HKDF
@@ -373,3 +374,35 @@
hkdf_test(backend, algorithm, params)
return test_hkdf
+
+
+def generate_rsa_pss_test(param_loader, path, file_names, hash_name):
+ all_params = _load_all_params(path, file_names, param_loader)
+ all_params = [i for i in all_params if i["algorithm"] == hash_name]
+
+ @pytest.mark.parametrize("params", all_params)
+ def test_rsa_pss(self, backend, params):
+ rsa_pss_test(backend, params)
+
+ return test_rsa_pss
+
+
+def rsa_pss_test(backend, params):
+ public_key = rsa.RSAPublicKey(
+ public_exponent=params["public_exponent"],
+ modulus=params["modulus"]
+ )
+ hash_cls = getattr(hashes, params["algorithm"].decode("utf8"))
+ verifier = public_key.verifier(
+ binascii.unhexlify(params["s"]),
+ padding.PSS(
+ mgf=padding.MGF1(
+ algorithm=hash_cls(),
+ salt_length=params["salt_length"]
+ )
+ ),
+ hash_cls(),
+ backend
+ )
+ verifier.update(binascii.unhexlify(params["msg"]))
+ verifier.verify()