A device and method for decrypting re-encrypted digital contents are discussed. According to an embodiment, the method includes receiving the re-encrypted digital content without a source encryption key from a source device connected to the target device, wherein the re-encrypted digital content is generated at the source device by: 1) decrypting an encrypted digital content which is previously encrypted in an external device, and 2) re-encrypting the decrypted digital content with the source encryption key; performing an addition operation by using a first target internal key and an identifier (ID); generating a target encryption key based on an output of the addition operation and a second target internal key by using a predetermined encryption algorithm, the second target internal key being associated with the target device; and decrypting the re-encrypted digital content using the target encryption key.