mayhem-firmware/firmware/application/keeloq_common.cpp

#include "keeloq_common.hpp"

uint32_t keeloq_encrypt(const uint32_t data, const uint64_t key) {
    uint32_t x = data, r;

    for (r = 0; r < 528; r++)
        x = (x >> 1) ^ ((bit(x, 0) ^ bit(x, 16) ^ (uint32_t)bit(key, r & 63) ^
                         bit(KEELOQ_NLF, g5(x, 1, 9, 20, 26, 31)))
                        << 31);

    return x;
}

uint32_t keeloq_decrypt(const uint32_t data, const uint64_t key) {
    uint32_t x = data, r;

    for (r = 0; r < 528; r++)
        x = (x << 1) ^ bit(x, 31) ^ bit(x, 15) ^ (uint32_t)bit(key, (15 - r) & 63) ^
            bit(KEELOQ_NLF, g5(x, 0, 8, 19, 25, 30));

    return x;
}

uint64_t keeloq_normal_learning(uint32_t data, const uint64_t key) {
    uint32_t k1, k2;

    data &= 0x0FFFFFFF;
    data |= 0x20000000;
    k1 = keeloq_decrypt(data, key);

    data &= 0x0FFFFFFF;
    data |= 0x60000000;
    k2 = keeloq_decrypt(data, key);

    return ((uint64_t)k2 << 32) | k1;
}