RC2 cipher algorithm

RC2 (Ron's Code 2 or Rivest's Cipher 2) is a block cipher (64-bit block length) with a variable key length developed by Ron Rivest. The algorithm is faster than the DES algorithm. Persistence may be greater or less than DES, depending on the key length. The RC2 algorithm is proprietary to RSA Security Inc. a license is required to use it.
In the United States, a key length for domestic use is recommended to be 128 bits, but the agreement between the Software Publishers Association (SPA) and the US government gives RC2 a special status, which means that it is allowed to export cipher keys up to 40 bits. 56-bit keys are allowed to use overseas branches of US companies.

A 128 bit RC2 key provides the same level of security as IDEA or Triple DES. RC2 is used extensively by developers whose products are exported outside the United States, since exporting DES has long been banned. RC2 is used, in particular, in non-US versions of Microsoft Outlook Express Express.

The structure of the RC2 algorithm is shown in the figure.