dss_sig_value: Pure python conversion of (r, s) to byte stream
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 7a0b9e7..7b3ffbc 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -27,11 +27,11 @@
import cryptography_vectors
from .utils import (
- check_backend_support, check_for_iface, load_cryptrec_vectors,
- load_fips_dsa_key_pair_vectors, load_fips_dsa_sig_vectors,
- load_fips_ecdsa_key_pair_vectors, load_fips_ecdsa_signing_vectors,
- load_hash_vectors, load_nist_vectors, load_pkcs1_vectors,
- load_rsa_nist_vectors, load_vectors_from_file,
+ check_backend_support, check_for_iface, dss_sig_value,
+ load_cryptrec_vectors, load_fips_dsa_key_pair_vectors,
+ load_fips_dsa_sig_vectors, load_fips_ecdsa_key_pair_vectors,
+ load_fips_ecdsa_signing_vectors, load_hash_vectors, load_nist_vectors,
+ load_pkcs1_vectors, load_rsa_nist_vectors, load_vectors_from_file,
raises_unsupported_algorithm, select_backends
)
@@ -125,6 +125,32 @@
check_backend_support(item)
+def test_dss_sig_value():
+ sig = dss_sig_value(1, 1)
+ assert sig == b"0\x06\x02\x01\x01\x02\x01\x01"
+
+ sig2 = dss_sig_value(1037234182290683143945502320610861668562885151617,
+ 559776156650501990899426031439030258256861634312)
+ assert sig2 == (
+ b'0-\x02\x15\x00\xb5\xaf0xg\xfb\x8bT9\x00\x13\xccg\x02\r\xdf\x1f,\x0b'
+ b'\x81\x02\x14b\r;"\xabP1D\x0c>5\xea\xb6\xf4\x81)\x8f\x9e\x9f\x08'
+ )
+
+ sig3 = dss_sig_value(0, 0)
+ assert sig3 == b"0\x06\x02\x01\x00\x02\x01\x00"
+
+
+def test_dss_sig_value_negative():
+ with pytest.raises(ValueError):
+ dss_sig_value(-1, 1)
+
+ with pytest.raises(ValueError):
+ dss_sig_value(1, -1)
+
+ with pytest.raises(ValueError):
+ dss_sig_value(-1, -1)
+
+
def test_load_nist_vectors():
vector_data = textwrap.dedent("""
# CAVS 11.1
diff --git a/tests/utils.py b/tests/utils.py
index 60b6f5a..d856513 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -80,6 +80,33 @@
assert exc_info.value._reason is reason
+def _int_to_asn1_int(i):
+ """
+ Used by dss_sig_value to convert python integers to ASN.1 integer bytes.
+ """
+ if i == 0:
+ return b'\x02\x01\x00'
+ if i < 0:
+ raise ValueError("This only supports positive integers right now.")
+ result = []
+ while i:
+ result.append(six.int2byte(i & 0xFF))
+ i >>= 8
+ # ASN.1 integers are stored big endian two's complement, so add a byte if
+ # the ordinal value of the last byte is over 0x7f.
+ if ord(result[-1]) > 127:
+ result.append(b"\x00")
+ result.reverse()
+ packed = b''.join(result)
+ return b"\x02" + chr(len(packed)).encode("ascii") + packed
+
+
+def dss_sig_value(r, s):
+ combined = _int_to_asn1_int(r) + _int_to_asn1_int(s)
+ sig = b"0" + chr(len(combined)).encode("ascii") + combined
+ return sig
+
+
def load_vectors_from_file(filename, loader):
with cryptography_vectors.open_vector_file(filename) as vector_file:
return loader(vector_file)