Monster Hunter Stories 2 blowfish key generation

MHS2_blowfish_keygen.cpp

#include <iostream>
#include <cstdint>


uint32_t HIDWORD(uint64_t v) {
    return v >> 32;
}

class MtRandom {
public:
    unsigned long field_0;
    unsigned long field_4;
    unsigned long field_8;
    unsigned long field_C;

    void Init(unsigned int seed)
    {
        int v2; // r12
        int v3; // r3
        unsigned int v4; // lr
        unsigned int v5; // r2
        int v6; // r1
        int v7; // r5

        v2 = 0x159A55E5;
        this->field_0 = 123456789;
        this->field_4 = 0x159A55E5;
        v3 = 521288629;
        v4 = 88675123;
        v5 = seed ^ 0xAC9365;
        v6 = 100;
        this->field_8 = 521288629;
        this->field_C = 88675123;
        do
        {
            v7 = v2;
            v2 = v3;
            v3 = v4;
            --v6;
            v5 ^= (0x65AC9365u >> (v5 & 3)) ^ ((v5 ^ (0x65AC9365u >> (v5 & 3))) >> 3) ^ ((v5 ^ (0x65AC9365u >> (v5 & 3))) >> 4) ^ (8 * (v5 ^ (0x65AC9365u >> (v5 & 3)))) ^ (16 * (v5 ^ (0x65AC9365u >> (v5 & 3))));
            v4 ^= v5 ^ (v5 << 15) ^ ((v5 ^ (v5 << 15)) >> 4) ^ (v4 >> 21);
        } while (v6);
        this->field_0 = v7;
        this->field_4 = v2;
        this->field_8 = v3;
        this->field_C = v4;
    }

    int nrand()
    {
        uint64_t v1; // kr00_8
        unsigned int v2; // r1
        int v3; // r1

        v1 = *(uint64_t*)&this->field_8;
        v2 = this->field_0 ^ (this->field_0 << 15);
        this->field_0 = this->field_4;
        *(uint64_t*)&this->field_4 = v1;
        v3 = v2 ^ (v2 >> 4) ^ HIDWORD(v1) ^ (HIDWORD(v1) >> 21);
        this->field_C = v3;
        return v3;
    }
};



int main() {
    const char alphabet[] = { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x2D, 0x5F, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x7B, 0x7C, 0x7D, 0x7E, 0x20, 0x00};

    MtRandom mrand;

    uint32_t rand_seed = 0x1FE01ED9;

    char output[56];

    bool unk_mode = 0;
    if (unk_mode == 1)
    {
        mrand.Init(rand_seed);
        for (size_t i = 0; i < 56; i++)
        {
            char x = alphabet[(unsigned int)mrand.nrand() % 0x62];
            output[i] = x;
        }
    }
    else
    {
        mrand.Init((rand_seed >> 1) + 1);
        for (size_t i = 0; i < 56; i++)
        {
            output[i] = alphabet[(unsigned int)mrand.nrand() % 0x62];
        }
    }

    for (int i = 0; i < 56; i++)
    {
        printf("%02X ", output[i]);
    }
    printf("\n");

	return 0;
}