redpike.cpp

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 * Copyright (C) Akiel Aries, <akiel@akiel.org>, et al.
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/*
 * Implementation of the Red Pike block cipher algorithm
 */
#include <cstdint>
#include <openGPMP/nt/redpike.hpp>
 
uint32_t gpmp::nt::RedPike::rotl(uint32_t X, int R) {
    return ((X) << ((R)&31)) | ((X) >> (32 - ((R)&31)));
}
 
uint32_t gpmp::nt::RedPike::rotr(uint32_t X, int R) {
    return ((X) >> ((R)&31)) | ((X) << (32 - ((R)&31)));
}
 
void gpmp::nt::RedPike::encrypt(uint32_t *x, const uint32_t *k) {
    uint32_t rk0 = k[0];
    uint32_t rk1 = k[1];
 
    for (int i = 0; i < ROUNDS; i++) {
        rk0 += CONST;
        rk1 -= CONST;
 
        x[0] ^= rk0;
        x[0] += x[1];
        x[0] = rotl(x[0], x[1]);
 
        x[1] = rotr(x[1], x[0]);
        x[1] -= x[0];
        x[1] ^= rk1;
    }
 
    rk0 = x[0];
    x[0] = x[1];
    x[1] = rk0;
}
 
void gpmp::nt::RedPike::decrypt(uint32_t *x, const uint32_t *k) {
    uint32_t dk[2] = {k[1] - CONST * (ROUNDS + 1), k[0] + CONST * (ROUNDS + 1)};
 
    encrypt(x, dk);
}