ADD file via upload

digital_signature.py

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+# digital_signature.py
+
+from cryptography.hazmat.primitives.asymmetric import utils
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.asymmetric import padding
+import os
+
+def digital_signature(file_path):
+    # 读取A的私钥
+    with open(os.path.join(os.path.dirname(__file__), 'A_private.txt'), 'r') as file:
+        private_key_data = file.read()
+        private_key = serialization.load_pem_private_key(
+            private_key_data.encode(),
+            password=None,
+            backend=default_backend()
+        )
+
+    # 读取原文
+    with open(file_path, 'rb') as file:
+        message = file.read()
+
+    # 计算摘要
+    hash_object = hashes.Hash(hashes.SHA256(), backend=default_backend())
+    hash_object.update(message)
+    hash_value = hash_object.finalize()
+
+    # 使用私钥进行签名
+    signature = private_key.sign(
+        hash_value,
+        padding.PSS(
+            mgf=padding.MGF1(hashes.SHA256()),
+            salt_length=padding.PSS.MAX_LENGTH
+        ),
+        utils.Prehashed(hashes.SHA256())
+    )
+
+    # 将签名保存到文件
+    with open(os.path.join(os.path.dirname(__file__), 'signature.txt'), 'wb') as file:
+        file.write(signature)
+
+    return hash_value.hex()
+