Block cipher mode of operation for secure, length-preserving encryption
US5673319A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 6, 1995 |
| Grant date | Sep 30, 1997 |
| Priority date | — |
| Expiry date | Feb 6, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L9/50
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method for encrypting a plaintext string into ciphertext begins by cipher block chaining (CBC) the plaintext using a first key and a null initialization vector to generate a CBC message authentication code (MAC) whose length is equal to the block length. The plaintext string is then cipher block chained again, now using a second key and the CBC-MAC as the initialization vector, to generate an enciphered string. The CBC-MAC and a prefix of the enciphered string comprising all of the enciphered string except the last block are then combined to create the ciphertext. The described mode of operation is length-preserving, yet has the property that related plaintexts give rise to unrelated ciphertexts.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.