def from_transformation()

in src/dynamodb_encryption_sdk/internal/crypto/jce_bridge/encryption.py [0:0]

• 16 lines of code
• 7 McCabe index (conditional complexity)

    def from_transformation(cls, cipher_transformation):
        """Generates an JavaCipher object from the Java transformation.
        https://docs.oracle.com/javase/8/docs/api/javax/crypto/Cipher.html
        https://docs.oracle.com/javase/8/docs/technotes/guides/security/StandardNames.html#Cipher

        :param str cipher_transformation: Formatted transformation
        :returns: JavaCipher instance
        :rtype: JavaCipher
        """
        if cipher_transformation == "AESWrap":
            # AESWrap does not support encrypt or decrypt, so mode and padding are never
            # used, but we use ECB and NoPadding as placeholders to simplify handling.
            return cls.from_transformation("AESWrap/ECB/NoPadding")

        if cipher_transformation == "RSA":
            # RSA does not use mode, but as with JCE, we use ECB as a placeholder to simplify handling.
            return cls.from_transformation("RSA/ECB/PKCS1Padding")

        cipher_transformation_parts = cipher_transformation.split("/")
        if len(cipher_transformation_parts) != 3:
            raise JceTransformationError(
                'Invalid transformation: "{}": must be three parts ALGORITHM/MODE/PADDING, "RSA", or "AESWrap"'.format(
                    cipher_transformation
                )
            )

        cipher = cls._map_load_or_error("algorithm", cipher_transformation_parts[0], JAVA_ENCRYPTION_ALGORITHM)
        mode = cls._map_load_or_error("mode", cipher_transformation_parts[1], JAVA_MODE)
        padding = cls._map_load_or_error("padding", cipher_transformation_parts[2], JAVA_PADDING)

        return cls(cipher, mode, padding)