Which Rivest Cipher uses a key size up to 2048 bits and is considered to be a strong system? Cryptography Which Rivest Cipher uses a key size up to 2048 bits and is considered to be a strong system? a. RC2 b. RC3 c. RC4 d. RC5 Answer: d. RC5 Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+