[#2] Add methods sign and verify

Signed-off-by: ilyas585 <niyazov2023@gmail.com>

frostfs_api/cryptography/verifier.py

@@ -0,0 +1,50 @@
+import ecdsa
+from hashlib import sha256, sha512
+
+
+class Verifier:
+    def verify_rfc6979(self, public_key: bytes, message: bytes, signature: bytes) -> bool:
+        """
+        Verify a signature using the public key.
+
+        :param public_key: Public key in byte format.
+        :param message: Signature verification message in byte format.
+        :param signature: Signature in byte format.
+        :return: True if the signature is correct, otherwise False.
+        :raises: ValueError: If the public_key key is incorrect.
+        """
+        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.NIST256p, hashfunc=sha256)
+
+        try:
+            return vk.verify(signature, message)
+        except ecdsa.BadSignatureError:
+            return False
+
+    def verify(self, public_key: bytes, message: bytes, signature: bytes) -> bool:
+        """
+        Verify a signature using the public key.
+
+        :param public_key: Public key in byte format.
+        :param message: Signature verification message in byte format.
+        :param signature: Signature in byte format.
+        :return: True if the signature is correct, otherwise False.
+        :raises: ValueError: If the public_key key is incorrect.
+        """
+        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.NIST256p, hashfunc=sha512)
+
+        try:
+            return vk.verify(signature, message)
+        except ecdsa.BadSignatureError:
+            return False