Collision Resistance;  Hash Functions;  Preimage Resistance;  Second Preimage Resistance

The RIPEMD Family designates a family of five different  Hash Functions: RIPEMD, RIPEMD-128, RIPEMD-160, RIPEMD-256, and RIPEMD-320 [1,  2]. They take variable length input messages and hash them to fixed-length outputs. They all operate on 512-bit message blocks divided into sixteen 32-bit words. RIPEMD (later replaced by RIPEMD-128/160) and RIPEMD-128 produce a hash value of 128 bits, RIPEMD-160, RIPEMD-256, and RIPEMD-320 have a hash result of 160, 256, and 320 bits, respectively. All the five functions start by padding the message according to the so-called Merkle–Damgård strengthening technique (refer to  Hash Functionsfor more details). Next, the message is processed block by block by the underlying compression function. This function initializes an appropriate number of 32-bit chaining variables to a fixed value to hash the first message block, and to the intermediate...