Description Unlike many schemes , RC5 has a variable block size -LRB- NUMBER@1 , NUMBER@2 or NUMBER@3 bits -RRB- , key size -LRB- NUMBER@4 to NUMBER@5 bits -RRB- and number of rounds -LRB- NUMBER@4 to NUMBER@6 -RRB- .

In order to provide varieties of security and efficiency levels ; RC5 has a variable block size -LRB- NUMBER@1 , NUMBER@2 or NUMBER@3 bits -RRB- , variable key size -LRB- NUMBER@4 to NUMBER@5 bits -RRB- and variable number of rounds -LRB- NUMBER@4 to NUMBER@6 -RRB- .
