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from __future__ import with_statement, division
import pytest
import hashlib
from six import b, binary_type
from .keys import SigningKey, VerifyingKey
from .keys import BadSignatureError
from .util import sigencode_der, sigencode_string
from .util import sigdecode_der, sigdecode_string
from .curves import curves, NIST256p, NIST521p
der_sigs = []
example_data = b("some data to sign")
# Just NIST256p with SHA256 is 560 test cases, all curves with all hashes is
# few thousand slow test cases; execute the most interesting only
#for curve in curves:
for curve in [NIST521p]:
#for hash_alg in ["md5", "sha1", "sha224", "sha256", "sha384", "sha512"]:
for hash_alg in ["sha256"]:
key = SigningKey.generate(curve)
signature = key.sign(example_data, hashfunc=getattr(hashlib, hash_alg),
sigencode=sigencode_der)
for pos in range(len(signature)):
for xor in (1<<i for i in range(8)):
der_sigs.append(pytest.param(
key.verifying_key, hash_alg,
signature, pos, xor,
id="{0}-{1}-pos-{2}-xor-{3}".format(
curve.name, hash_alg, pos, xor)))
@pytest.mark.parametrize("verifying_key,hash_alg,signature,pos,xor", der_sigs)
def test_fuzzed_der_signatures(verifying_key, hash_alg, signature, pos, xor):
# check if a malformed DER encoded signature causes the same exception
# to be raised irrespective of the type of error
sig = bytearray(signature)
sig[pos] ^= xor
sig = binary_type(sig)
try:
verifying_key.verify(sig, example_data, getattr(hashlib, hash_alg),
sigdecode_der)
assert False
except BadSignatureError:
assert True
####
#
# For string encoded signatures, only the length of string is important
#
####
str_sigs = []
#for curve in curves:
for curve in [NIST256p]:
#for hash_alg in ["md5", "sha1", "sha224", "sha256", "sha384", "sha512"]:
for hash_alg in ["sha256"]:
key = SigningKey.generate(curve)
signature = key.sign(example_data, hashfunc=getattr(hashlib, hash_alg),
sigencode=sigencode_string)
for trunc in range(len(signature)):
str_sigs.append(pytest.param(
key.verifying_key, hash_alg,
signature, trunc,
id="{0}-{1}-trunc-{2}".format(
curve.name, hash_alg, trunc)))
@pytest.mark.parametrize("verifying_key,hash_alg,signature,trunc", str_sigs)
def test_truncated_string_signatures(verifying_key, hash_alg, signature, trunc):
# check if a malformed string encoded signature causes the same exception
# to be raised irrespective of the type of error
sig = bytearray(signature)
sig = sig[:trunc]
sig = binary_type(sig)
try:
verifying_key.verify(sig, example_data, getattr(hashlib, hash_alg),
sigdecode_string)
assert False
except BadSignatureError:
assert True
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