keygen.py

@@ -1,100 +0,0 @@
-import hmac
-import hashlib
-import base64
-
-salt = "UqEEf08yMDE3qIQodAGAyNQ2EPFhb26f2o85MTIyMeAAkqlANiXcF"
-
-def generate_secret_key(identifier: str, expiry: str) -> str:
-    """
-    Generate a secret key with the following structure:
-      - encoded_data: Base64 encoding of (identifier + expiry)
-      - signature: 32 characters from the URL-safe base64 HMAC signature
-      - id_length_hex: 2-character hexadecimal number representing the length of the identifier
-    The HMAC is computed over (encoded_data + id_length_hex).
-    """
-    global salt
-    if len(identifier) > 255:
-        raise ValueError("Identifier must be at most 255 characters long.")
-    if len(expiry) != 8:
-        raise ValueError("Expiry must be an 8-character string in DDMMYYYY format.")
-    
-    # Concatenate identifier and expiry, then base64 encode the result.
-    plain_data = identifier + expiry
-    # Remove padding for compactness; we'll add it back during decoding.
-    encoded_data = base64.urlsafe_b64encode(plain_data.encode()).decode().rstrip("=")
-    
-    # Format the length of the identifier as a 2-digit hexadecimal string.
-    id_length_hex = f"{len(identifier):02X}"
-    
-    # Build the message for HMAC: encoded_data + id_length_hex.
-    message = encoded_data + id_length_hex
-    
-    # Compute HMAC using SHA-256.
-    hmac_digest = hmac.new(salt.encode(), message.encode(), hashlib.sha256).digest()
-    
-    # Get a URL-safe base64 representation and take the first 32 characters as the signature.
-    signature = base64.urlsafe_b64encode(hmac_digest).decode()[:32]
-    
-    # Construct the final secret key.
-    secret_key = encoded_data + signature + id_length_hex
-    return secret_key
-
-def decode_secret_key(secret_key: str):
-    """
-    Decode the secret key and extract the identifier and expiry.
-    
-    Token structure:
-      - encoded_data: secret_key[0 : (len(secret_key)-34)] (variable length)
-      - signature: secret_key[-34:-2] (32 characters)
-      - id_length_hex: secret_key[-2:] (2 characters)
-    
-    The HMAC is verified over (encoded_data + id_length_hex). Then, encoded_data is base64-decoded 
-    (with proper padding added) to yield (identifier + expiry), where the last 8 characters represent expiry.
-    The identifier length is determined from id_length_hex.
-    """
-    global salt
-    
-    if len(secret_key) < 34:  # Must at least have signature (32) + id_length_hex (2)
-        raise ValueError("Invalid key length.")
-    
-    # Extract the last 2 characters: id_length_hex.
-    id_length_hex = secret_key[-2:]
-    try:
-        id_length = int(id_length_hex, 16)
-    except ValueError:
-        raise ValueError("Invalid identifier length prefix in key.")
-    
-    # The signature is the 32 characters preceding the last 2.
-    signature = secret_key[-34:-2]
-    # The remainder is the encoded_data.
-    encoded_data = secret_key[:-34]
-    
-    # Verify the signature.
-    message = encoded_data + id_length_hex
-    expected_hmac = hmac.new(salt.encode(), message.encode(), hashlib.sha256).digest()
-    expected_signature = base64.urlsafe_b64encode(expected_hmac).decode()[:32]
-    
-    if not hmac.compare_digest(signature, expected_signature):
-        raise ValueError("Invalid key signature.")
-    
-    # Base64-decode the encoded_data.
-    # Add back any missing '=' padding.
-    padding = '=' * (-len(encoded_data) % 4)
-    plain_data = base64.urlsafe_b64decode(encoded_data + padding).decode()
-    
-    # plain_data should be (identifier + expiry), where expiry is the last 8 characters.
-    if len(plain_data) != id_length + 8:
-        raise ValueError("Decoded data length does not match expected identifier length and expiry.")
-    
-    identifier = plain_data[:id_length]
-    expiry = plain_data[id_length:]
-    
-    return identifier, expiry
-
-
-if __name__ == '__main__':
-    key = generate_secret_key("Besondere Gottesdienste", "30042025")
-    print(key)
-    identifier, expiry = decode_secret_key(key)
-    print("identifier:", identifier)
-    print("expiry:", expiry)