 The MIX transformation of RC2; four of these comprise a MIXING round | |
| General | |
|---|---|
| Designers | Ron Rivest |
| First published | Leaked in 1996, designed in 1987, officially published in 1998 |
| Cipher detail | |
| Key sizes | 1–128 bytes |
| Block sizes | 64 bits |
| Structure | Source-heavy unbalancedFeistel network |
| Rounds | 16 of type MIXING, 2 of type MASHING |
| Best publiccryptanalysis | |
| Arelated-key attack is possible requiring 234chosen plaintexts (Kelsey et al., 1997). | |
Incryptography,RC2 (also known asARC2) is asymmetric-keyblock cipher designed byRon Rivest in 1987. "RC" stands for "Ron's Code"[1] (see alsoRC2,RC5 andRC6), but generally called simply RC2. Other ciphers designed by Ron Rivest includeRC4,RC5, andRC6.
The development of RC2 was sponsored byLotus, who were seeking a customcipher that, after evaluation by theNSA, could be exported as part of theirLotus Notes software. The NSA suggested a few changes, which Rivest incorporated. After further negotiations, the cipher was approved for export in 1989. Along with RC4, RC2 with a40-bitkey size was treated favourably under USexport regulations for cryptography.
Initially, the details of the algorithm were kept secret — proprietary toRSA Security — but on 29 January 1996, source code for RC2 was anonymously posted to the Internet on theUsenet forumsci.crypt. Mentions ofCodeView andSoftICE (populardebuggers) suggest that it had beenreverse engineered. A similar disclosure had occurred earlier with RC4.
In March 1998, Ron Rivest authored anRFC publicly describing RC2 himself.[2]
RC2 is a64-bit block cipher with a variable sizekey. Its 18 rounds are arranged as a source-heavy unbalancedFeistel network, with 16 rounds of one type (MIXING) punctuated by two rounds of another type (MASHING). A MIXING round consists of four applications of the MIX transformation, as shown in the diagram.
RC2 is vulnerable to arelated-key attack using 234chosen plaintexts.[3]
