1 files changed, 106 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/dns/dnssecalgs/dsa.py b/.venv/lib/python3.12/site-packages/dns/dnssecalgs/dsa.py
new file mode 100644
index 00000000..adca3def
--- /dev/null
+++ b/.venv/lib/python3.12/site-packages/dns/dnssecalgs/dsa.py
@@ -0,0 +1,106 @@
+import struct
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.asymmetric import dsa, utils
+
+from dns.dnssecalgs.cryptography import CryptographyPrivateKey, CryptographyPublicKey
+from dns.dnssectypes import Algorithm
+from dns.rdtypes.ANY.DNSKEY import DNSKEY
+
+
+class PublicDSA(CryptographyPublicKey):
+    key: dsa.DSAPublicKey
+    key_cls = dsa.DSAPublicKey
+    algorithm = Algorithm.DSA
+    chosen_hash = hashes.SHA1()
+
+    def verify(self, signature: bytes, data: bytes) -> None:
+        sig_r = signature[1:21]
+        sig_s = signature[21:]
+        sig = utils.encode_dss_signature(
+            int.from_bytes(sig_r, "big"), int.from_bytes(sig_s, "big")
+        )
+        self.key.verify(sig, data, self.chosen_hash)
+
+    def encode_key_bytes(self) -> bytes:
+        """Encode a public key per RFC 2536, section 2."""
+        pn = self.key.public_numbers()
+        dsa_t = (self.key.key_size // 8 - 64) // 8
+        if dsa_t > 8:
+            raise ValueError("unsupported DSA key size")
+        octets = 64 + dsa_t * 8
+        res = struct.pack("!B", dsa_t)
+        res += pn.parameter_numbers.q.to_bytes(20, "big")
+        res += pn.parameter_numbers.p.to_bytes(octets, "big")
+        res += pn.parameter_numbers.g.to_bytes(octets, "big")
+        res += pn.y.to_bytes(octets, "big")
+        return res
+
+    @classmethod
+    def from_dnskey(cls, key: DNSKEY) -> "PublicDSA":
+        cls._ensure_algorithm_key_combination(key)
+        keyptr = key.key
+        (t,) = struct.unpack("!B", keyptr[0:1])
+        keyptr = keyptr[1:]
+        octets = 64 + t * 8
+        dsa_q = keyptr[0:20]
+        keyptr = keyptr[20:]
+        dsa_p = keyptr[0:octets]
+        keyptr = keyptr[octets:]
+        dsa_g = keyptr[0:octets]
+        keyptr = keyptr[octets:]
+        dsa_y = keyptr[0:octets]
+        return cls(
+            key=dsa.DSAPublicNumbers(  # type: ignore
+                int.from_bytes(dsa_y, "big"),
+                dsa.DSAParameterNumbers(
+                    int.from_bytes(dsa_p, "big"),
+                    int.from_bytes(dsa_q, "big"),
+                    int.from_bytes(dsa_g, "big"),
+                ),
+            ).public_key(default_backend()),
+        )
+
+
+class PrivateDSA(CryptographyPrivateKey):
+    key: dsa.DSAPrivateKey
+    key_cls = dsa.DSAPrivateKey
+    public_cls = PublicDSA
+
+    def sign(
+        self,
+        data: bytes,
+        verify: bool = False,
+        deterministic: bool = True,
+    ) -> bytes:
+        """Sign using a private key per RFC 2536, section 3."""
+        public_dsa_key = self.key.public_key()
+        if public_dsa_key.key_size > 1024:
+            raise ValueError("DSA key size overflow")
+        der_signature = self.key.sign(data, self.public_cls.chosen_hash)
+        dsa_r, dsa_s = utils.decode_dss_signature(der_signature)
+        dsa_t = (public_dsa_key.key_size // 8 - 64) // 8
+        octets = 20
+        signature = (
+            struct.pack("!B", dsa_t)
+            + int.to_bytes(dsa_r, length=octets, byteorder="big")
+            + int.to_bytes(dsa_s, length=octets, byteorder="big")
+        )
+        if verify:
+            self.public_key().verify(signature, data)
+        return signature
+
+    @classmethod
+    def generate(cls, key_size: int) -> "PrivateDSA":
+        return cls(
+            key=dsa.generate_private_key(key_size=key_size),
+        )
+
+
+class PublicDSANSEC3SHA1(PublicDSA):
+    algorithm = Algorithm.DSANSEC3SHA1
+
+
+class PrivateDSANSEC3SHA1(PrivateDSA):
+    public_cls = PublicDSANSEC3SHA1