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The RC algorithms are a set of symmetric-key encryption algorithms invented by Ron Rivest. The "RC" may stand for either Rivest's cipher or, more informally, Ron's code.[1] Despite the similarity in their names, the algorithms are for the most part unrelated. There have been six RC algorithms so far:

  • RC1 was never published.
  • RC2 was a 64-bit block cipher developed in 1987.
  • RC3 was broken before ever being used.
  • RC4 is the world's most widely used stream cipher.
  • RC5 is a 32/64/128-bit block cipher developed in 1994.
  • RC6, a 128-bit block cipher based heavily on RC5[2], was an AES finalist developed in 1997.