Initial commit

venv/Lib/site-packages/ecdsa/rfc6979.py

@@ -0,0 +1,113 @@
+"""
+RFC 6979:
+    Deterministic Usage of the Digital Signature Algorithm (DSA) and
+    Elliptic Curve Digital Signature Algorithm (ECDSA)
+
+    http://tools.ietf.org/html/rfc6979
+
+Many thanks to Coda Hale for his implementation in Go language:
+    https://github.com/codahale/rfc6979
+"""
+
+import hmac
+from binascii import hexlify
+from .util import number_to_string, number_to_string_crop, bit_length
+from ._compat import hmac_compat
+
+
+# bit_length was defined in this module previously so keep it for backwards
+# compatibility, will need to deprecate and remove it later
+__all__ = ["bit_length", "bits2int", "bits2octets", "generate_k"]
+
+
+def bits2int(data, qlen):
+    x = int(hexlify(data), 16)
+    l = len(data) * 8
+
+    if l > qlen:
+        return x >> (l - qlen)
+    return x
+
+
+def bits2octets(data, order):
+    z1 = bits2int(data, bit_length(order))
+    z2 = z1 - order
+
+    if z2 < 0:
+        z2 = z1
+
+    return number_to_string_crop(z2, order)
+
+
+# https://tools.ietf.org/html/rfc6979#section-3.2
+def generate_k(order, secexp, hash_func, data, retry_gen=0, extra_entropy=b""):
+    """
+    Generate the ``k`` value - the nonce for DSA.
+
+    :param int order: order of the DSA generator used in the signature
+    :param int secexp: secure exponent (private key) in numeric form
+    :param hash_func: reference to the same hash function used for generating
+        hash, like :py:class:`hashlib.sha1`
+    :param bytes data: hash in binary form of the signing data
+    :param int retry_gen: how many good 'k' values to skip before returning
+    :param bytes extra_entropy: additional added data in binary form as per
+        section-3.6 of rfc6979
+    :rtype: int
+    """
+
+    qlen = bit_length(order)
+    holen = hash_func().digest_size
+    rolen = (qlen + 7) // 8
+    bx = (
+        hmac_compat(number_to_string(secexp, order)),
+        hmac_compat(bits2octets(data, order)),
+        hmac_compat(extra_entropy),
+    )
+
+    # Step B
+    v = b"\x01" * holen
+
+    # Step C
+    k = b"\x00" * holen
+
+    # Step D
+
+    k = hmac.new(k, digestmod=hash_func)
+    k.update(v + b"\x00")
+    for i in bx:
+        k.update(i)
+    k = k.digest()
+
+    # Step E
+    v = hmac.new(k, v, hash_func).digest()
+
+    # Step F
+    k = hmac.new(k, digestmod=hash_func)
+    k.update(v + b"\x01")
+    for i in bx:
+        k.update(i)
+    k = k.digest()
+
+    # Step G
+    v = hmac.new(k, v, hash_func).digest()
+
+    # Step H
+    while True:
+        # Step H1
+        t = b""
+
+        # Step H2
+        while len(t) < rolen:
+            v = hmac.new(k, v, hash_func).digest()
+            t += v
+
+        # Step H3
+        secret = bits2int(t, qlen)
+
+        if 1 <= secret < order:
+            if retry_gen <= 0:
+                return secret
+            retry_gen -= 1
+
+        k = hmac.new(k, v + b"\x00", hash_func).digest()
+        v = hmac.new(k, v, hash_func).digest()