Pseudo-code for RIPEMD-128
RIPEMD-128 is an iterative hash function that operates on 32-bit words.
The round function takes as input a 4-word chaining variable and a 16-word
message block and maps this to a new chaining variable. All operations are
defined on 32-bit words. Padding is identical to that of MD4.
RIPEMD-128: definitions
nonlinear functions at bit level: exor, mux, -, mux
f(j, x, y, z) = x XOR y XOR z (0 <= j <= 15)
f(j, x, y, z) = (x AND y) OR (NOT(x) AND z) (16 <= j <= 31)
f(j, x, y, z) = (x OR NOT(y)) XOR z (32 <= j <= 47)
f(j, x, y, z) = (x AND z) OR (y AND NOT(z)) (48 <= j <= 63)
added constants (hexadecimal)
K(j) = 0x00000000 (0 <= j <= 15)
K(j) = 0x5A827999 (16 <= j <= 31) int(2**30 x sqrt(2))
K(j) = 0x6ED9EBA1 (32 <= j <= 47) int(2**30 x sqrt(3))
K(j) = 0x8F1BBCDC (48 <= j <= 63) int(2**30 x sqrt(5))
K'(j) = 0x50A28BE6 (0 <= j <= 15) int(2**30 x cbrt(2))
K'(j) = 0x5C4DD124 (16 <= j <= 31) int(2**30 x cbrt(3))
K'(j) = 0x6D703EF3 (32 <= j <= 47) int(2**30 x cbrt(5))
K'(j) = 0x00000000 (48 <= j <= 63)
selection of message word
r(j) = j (0 <= j <= 15)
r(16..31) = 7, 4, 13, 1, 10, 6, 15, 3, 12, 0, 9, 5, 2, 14, 11, 8
r(32..47) = 3, 10, 14, 4, 9, 15, 8, 1, 2, 7, 0, 6, 13, 11, 5, 12
r(48..63) = 1, 9, 11, 10, 0, 8, 12, 4, 13, 3, 7, 15, 14, 5, 6, 2
r'(0..15) = 5, 14, 7, 0, 9, 2, 11, 4, 13, 6, 15, 8, 1, 10, 3, 12
r'(16..31)= 6, 11, 3, 7, 0, 13, 5, 10, 14, 15, 8, 12, 4, 9, 1, 2
r'(32..47)= 15, 5, 1, 3, 7, 14, 6, 9, 11, 8, 12, 2, 10, 0, 4, 13
r'(48..63)= 8, 6, 4, 1, 3, 11, 15, 0, 5, 12, 2, 13, 9, 7, 10, 14
amount for rotate left (rol)
s(0..15) = 11, 14, 15, 12, 5, 8, 7, 9, 11, 13, 14, 15, 6, 7, 9, 8
s(16..31) = 7, 6, 8, 13, 11, 9, 7, 15, 7, 12, 15, 9, 11, 7, 13, 12
s(32..47) = 11, 13, 6, 7, 14, 9, 13, 15, 14, 8, 13, 6, 5, 12, 7, 5
s(48..63) = 11, 12, 14, 15, 14, 15, 9, 8, 9, 14, 5, 6, 8, 6, 5, 12
s'(0..15) = 8, 9, 9, 11, 13, 15, 15, 5, 7, 7, 8, 11, 14, 14, 12, 6
s'(16..31)= 9, 13, 15, 7, 12, 8, 9, 11, 7, 7, 12, 7, 6, 15, 13, 11
s'(32..47)= 9, 7, 15, 11, 8, 6, 6, 14, 12, 13, 5, 14, 13, 13, 7, 5
s'(48..63)= 15, 5, 8, 11, 14, 14, 6, 14, 6, 9, 12, 9, 12, 5, 15, 8
initial value (hexadecimal)
h0 = 0x67452301; h1 = 0xEFCDAB89; h2 = 0x98BADCFE; h3 = 0x10325476;
RIPEMD-128: pseudo-code
It is assumed that the message after padding consists of t 16-word blocks
that will be denoted with X[i][j], with 0 <= i <= t-1 and 0 <= j <= 15.
The symbol [+] denotes addition modulo 2**32 and rol_s denotes cyclic left
shift (rotate) over s positions.
for i := 0 to t-1 {
A := h0; B := h1; C := h2; D = h3;
A' := h0; B' := h1; C' := h2; D' = h3;
for j := 0 to 63 {
T := rol_s(j)(A [+] f(j, B, C, D) [+] X[i][r(j)] [+] K(j));
A := D; D := C; C := B; B := T;
T := rol_s'(j)(A' [+] f(63-j, B', C', D') [+] X[i][r'(j)] [+] K'(j));
A' := D'; D' := C'; C' := B'; B' := T;
}
T := h1 [+] C [+] D'; h1 := h2 [+] D [+] A'; h2 := h3 [+] A [+] B';
h3 := h0 [+] B [+] C'; h0 := T;
}