A device and method for decrypting digital contents are discussed. According to an embodiment, a method for decrypting digital content at a target device, includes receiving the digital content without a source encryption key from a source device connected to the target device, the digital content having been encrypted with the source encryption key in the source device, wherein the source device is configured to perform an authenticating operation with the target device by using an identifier (ID) associated with at least one of the target device and a storage medium of the target device; performing a first addition operation by using a first target internal key and the ID; generating a target encryption key based on an output of the first addition operation and a second target internal key by using a predetermined encryption algorithm; and decrypting the encrypted digital content using the target encryption key.