| Abstract | Most encryption schemes always use the same decryption key to convert a particular codetext into plaintext. If a decryption key that has been revealed to multiple parties is compromised, it is impossible to determine who is responsible for the breach. Heraclitean encryption, which uses public-key encryption (for instance, RSA or elliptic curve) as its cryptographic basis, permits the encryptor to create as many independent decryption keys as desired. Each decryption key can publicly encode information about the party to whom it was issued, so that given a key, anyone can determine its owner. Since decryption keys can be traced, their holders have an incentive to keep them secret. \par We discuss applications of Heraclitean encryption, provide an example implementation, discuss weaknesses in that implementation, and explore some practicalities of using the scheme. \par We do not address the issue of tracking decrypted information back to the decryptor; the plaintext is identical for each recipient. Heraclitean encryption is applicable to any broadcast medium that can carry proprietary information–-for instance, pay-per-view video and wide distribution of commercial software or databases via CD-ROM or bulletin boards. |
