To leverage the efficiency and the scalability of BitTorrent (BT) systems for Internet content distribution, the present invention discloses enhancing BT peer-to-peer systems to enable digital rights management without infrastructure changes. The technique involves runtime re-encryption of each file piece, which may already be encrypted, before a peer uploads it to any other peer. To access the re-encrypted pieces, a tracker site generates decryption keys that are unique for each peer and for each file piece. While any user can take part in the content distribution, only legitimate users with the unique decryption keys can access the plaintext of the encrypted distributed content.