'init'

crypto_utils.py

@@ -0,0 +1,62 @@
+import base64
+import hashlib
+from typing import Tuple
+
+from Crypto.Cipher import AES
+
+
+BLOCK_SIZE = 32  # PKCS5/PKCS7 padding 使用 32 字节块大小
+
+
+def pkcs5_unpadding(data: bytes) -> bytes:
+    pad = data[-1]
+    if pad < 1 or pad > 32:
+        return data
+    return data[:-pad]
+
+
+def pkcs5_padding(data: bytes) -> bytes:
+    amount_to_pad = BLOCK_SIZE - (len(data) % BLOCK_SIZE)
+    return data + bytes([amount_to_pad]) * amount_to_pad
+
+
+def get_aes_key_and_iv(encoding_aes_key: str) -> Tuple[bytes, bytes]:
+    """
+    encoding_aes_key 是平台给的 43 位字符串，需要先补一个 '=' 再 base64 解码。
+    得到 32 字节 key，前 16 字节为 iv。
+    """
+    aes_key = base64.b64decode(encoding_aes_key + "=")
+    if len(aes_key) != 32:
+        raise ValueError("encodingAESKey 无效，解码后长度不是 32 字节")
+    iv = aes_key[:16]
+    return aes_key, iv
+
+
+def aes_decrypt_base64(cipher_b64: str, encoding_aes_key: str) -> str:
+    aes_key, iv = get_aes_key_and_iv(encoding_aes_key)
+    cipher_bytes = base64.b64decode(cipher_b64)
+    cipher = AES.new(aes_key, AES.MODE_CBC, iv)
+    decrypted = cipher.decrypt(cipher_bytes)
+    decrypted = pkcs5_unpadding(decrypted)
+    return decrypted.decode("utf-8")
+
+
+def aes_encrypt_base64(plaintext: str, encoding_aes_key: str) -> str:
+    aes_key, iv = get_aes_key_and_iv(encoding_aes_key)
+    data = plaintext.encode("utf-8")
+    padded = pkcs5_padding(data)
+    cipher = AES.new(aes_key, AES.MODE_CBC, iv)
+    encrypted = cipher.encrypt(padded)
+    return base64.b64encode(encrypted).decode("utf-8")
+
+
+def calc_signature(token: str, timestamp: int, skill_name: str, intent_name: str, query: str) -> str:
+    """
+    文档签名算法：
+    str = token + time.Now.Unix + skill_name + intent_name + query
+    signature = MD5(str)  小写 hex
+    参考：https://developers.weixin.qq.com/doc/aispeech/confapi/thirdapi/thirdapi.html
+    """
+    s = f"{token}{timestamp}{skill_name}{intent_name}{query}"
+    return hashlib.md5(s.encode("utf-8")).hexdigest()
+