[#2] Add methods sign and verify

.idea/.gitignore

@@ -0,0 +1,3 @@
+# Default ignored files
+/shelf/
+/workspace.xml

frostfs_api/client/signer.py

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+import ecdsa
+from hashlib import sha256
+
+
+class Signer:
+    def sign_rfc6979(self, private_key: bytes, message: bytes) -> bytes:
+        if len(private_key) == 0 or private_key is None:
+            raise ValueError(f"Incorrect private_key: {private_key}")
+
+        # SECP256k1 is the Bitcoin elliptic curve
+        sk = ecdsa.SigningKey.from_string(private_key, curve=ecdsa.SECP256k1, hashfunc=sha256)
+
+        signature = sk.sign(message, sigencode=ecdsa.util.sigencode_string)
+
+        return signature

frostfs_api/client/verifier.py

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+import ecdsa
+from hashlib import sha256
+
+
+class Verifier:
+    def verify_rfc6979(self, public_key: bytes, message: bytes, signature: bytes) -> bool:
+        if len(public_key) == 0 or public_key is None:
+            raise ValueError(f"Incorrect public key: {public_key}")
+
+        if message is None or signature is None:
+            return False
+
+        vk = ecdsa.VerifyingKey.from_string(public_key, curve=ecdsa.SECP256k1, hashfunc=sha256)
+
+        try:
+            return vk.verify(signature, message)
+        except ecdsa.BadSignatureError:
+            return False

frostfs_api/crypto/key_extension.py

@@ -1,11 +1,21 @@
 import base58
+import ecdsa
 
 
 class KeyExtension:
-    def get_private_key_from_wif(self, wif: str):
+    def get_private_key_from_wif(self, wif: str) -> bytes:
+        if len(wif) == 0 or wif is None:
+            raise ValueError(f"Empty WIF private key: {wif}")
+
         decoded = base58.b58decode_check(wif)
         if len(decoded) != 34 or decoded[0] != 0x80 or decoded[-1] != 0x01:
-            raise ValueError("Incorrect WIF private key")
+            raise ValueError("Not decode WIF by base58")
 
         private_key = decoded[1:-1]
         return private_key
+
+    def get_public_key(self, private_key: bytes):
+        if len(private_key) == 0 or private_key is None:
+            raise ValueError(f"Empty private key: {private_key}")
+
+        return ecdsa.SigningKey.from_string(private_key, curve=ecdsa.SECP256k1).get_verifying_key().to_string()

pytest.ini

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+[pytest]
+
+#   tests markers
+crypto: cryptographic functions tests

requirements.txt

@@ -1,3 +1,4 @@
 base58==2.1.1
 ecdsa==0.19.0
+
 pytest==8.3.4

tests/client/test_sign_verify.py

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+import ecdsa
+import pytest
+
+from frostfs_api.client.signer import Signer
+from frostfs_api.client.verifier import Verifier
+from frostfs_api.crypto.key_extension import KeyExtension
+from tests.helpers.resources import WIF
+
+
+@pytest.mark.crypto
+class TestSignAndVerify:
+
+    @pytest.mark.parametrize("message", [b"Hello Frostfs API", b""])
+    def test_sign_verify_success(
+            self,
+            client_signer: Signer,
+            client_verifier: Verifier,
+            client_key_extension: KeyExtension,
+            message: bytes
+    ):
+        private_key = client_key_extension.get_private_key_from_wif(WIF)
+        public_key = client_key_extension.get_public_key(private_key)
+
+        signature = client_signer.sign_rfc6979(private_key, message)
+        assert client_verifier.verify_rfc6979(public_key, message, signature) is True
+
+    def test_verify_rfc6979_empty_key(self, client_verifier: Verifier):
+        with pytest.raises(ValueError, match="Incorrect public key"):
+            client_verifier.verify_rfc6979(b'', b"Test message", b"signature")

tests/crypto/test_key_extension.py

@@ -1,16 +1,23 @@
+import pytest
+
 from frostfs_api.crypto.key_extension import KeyExtension
 from tests.helpers.convert import convert_bytes_format_127_to_256
+from tests.helpers.resources import WIF, PRIVATE_KEY
 
 
+@pytest.mark.crypto
 class TestKeyExtension:
-    WIF = "L1YS4myg3xHPvi3FHeLaEt7G8upwJaWL5YLV7huviuUtXFpzBMqZ"
-    PRIVATE_KEY = [
-        -128, -5, 30, -36, -118, 85, -67, -6, 81, 43, 93, -38, 106, 21, -88, 127, 15, 125, -79, -17, -40, 77, -15,
-        122, -88, 72, 109, -47, 125, -80, -40, -38
-    ]
-
     def test_get_private_key_from_wif_success(self, client_key_extension: KeyExtension):
-        private_key = client_key_extension.get_private_key_from_wif(self.WIF)
+        private_key = client_key_extension.get_private_key_from_wif(WIF)
 
         assert len(private_key) == 32, f"Not correct len of private key, expected: 32 Actual: {len(private_key)} "
-        assert private_key == bytes(convert_bytes_format_127_to_256(self.PRIVATE_KEY)), f"Not match private key, Expected: {self.PRIVATE_KEY}, Actual: {private_key}"
+        assert private_key == bytes(convert_bytes_format_127_to_256(PRIVATE_KEY)), \
+            f"Not match private key, Expected: {PRIVATE_KEY}, Actual: {private_key}"
+
+    def test_get_private_key_empty_wif(self, client_key_extension: KeyExtension):
+        with pytest.raises(ValueError, match="Empty WIF private"):
+            client_key_extension.get_private_key_from_wif("")
+
+    def test_get_private_key_incorrect_wif(self, client_key_extension: KeyExtension):
+        with pytest.raises(ValueError, match="Invalid checksum"):
+            client_key_extension.get_private_key_from_wif("AAAAAAABBBBBBBBBBBCCCCCCCDDDDDDDDDDDDDDDDD")

tests/helpers/resources.py

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+WIF = "L1YS4myg3xHPvi3FHeLaEt7G8upwJaWL5YLV7huviuUtXFpzBMqZ"
+PRIVATE_KEY = [
+        -128, -5, 30, -36, -118, 85, -67, -6, 81, 43, 93, -38, 106, 21, -88, 127, 15, 125, -79, -17, -40, 77, -15,
+        122, -88, 72, 109, -47, 125, -80, -40, -38
+    ]