/* $OpenBSD: yubikey.c,v 1.6 2017/09/16 08:07:15 anton Exp $ */

/*
 * Written by Simon Josefsson <simon@josefsson.org>.
 * Copyright (c) 2006, 2007, 2008, 2009 Yubico AB
 * Copyright (c) 2010 Daniel Hartmeier <daniel@benzedrine.cx>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <ctype.h>
#include <stdlib.h>
#include <wchar.h>
#include <locale.h>
#include <errno.h>

#include "yubikey.h"
#include "keymaps.h"

static const uint8_t RC[] = {
        0x1, 0x2, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36
};

static const uint8_t rijndael_sbox[] = {
        0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5,
        0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
        0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0,
        0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
        0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC,
        0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
        0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A,
        0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
        0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0,
        0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
        0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B,
        0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
        0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85,
        0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
        0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5,
        0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
        0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17,
        0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
        0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88,
        0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
        0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C,
        0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
        0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9,
        0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
        0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6,
        0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
        0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E,
        0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
        0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94,
        0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
        0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68,
        0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
};

static const uint8_t rijndael_inv_sbox[] = {
        0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38,
        0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
        0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87,
        0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
        0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D,
        0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
        0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2,
        0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
        0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16,
        0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
        0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA,
        0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
        0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A,
        0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
        0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02,
        0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
        0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA,
        0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
        0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85,
        0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
        0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89,
        0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
        0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20,
        0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
        0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31,
        0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
        0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D,
        0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
        0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0,
        0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
        0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26,
        0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
};

static inline uint8_t
xtime(uint8_t b)
{
        return (b & 0x80) ? ((b << 1) ^ 0x1b) : (b << 1);
}

#define NUMBER_OF_ROUNDS 10

void
yubikey_aes_decrypt(uint8_t *state, const uint8_t *key)
{
        uint8_t i, j, round_key[0x10];
        uint8_t a02x, a13x;
        uint8_t a02xx, a13xx;
        uint8_t k1, k2;

        memcpy(round_key, key, sizeof(round_key));
        for (i = 0; i < NUMBER_OF_ROUNDS; i++) {
                round_key[0] ^= RC[i];

                round_key[0] ^= rijndael_sbox[round_key[13]];
                round_key[1] ^= rijndael_sbox[round_key[14]];
                round_key[2] ^= rijndael_sbox[round_key[15]];
                round_key[3] ^= rijndael_sbox[round_key[12]];

                for (j = 4; j < 16; j++)
                        round_key[j] ^= round_key[j - 4];
        }
        for (i = 0; i < 0x10; i++)
                state[i] ^= round_key[i];

        for (i = 1; i <= NUMBER_OF_ROUNDS; i++) {
                /* inv_byte_sub_shift_row(); */

                /* First row: 0 shift, 0 4 8 12 */
                state[0] = rijndael_inv_sbox[state[0]];
                state[4] = rijndael_inv_sbox[state[4]];
                state[8] = rijndael_inv_sbox[state[8]];
                state[12] = rijndael_inv_sbox[state[12]];

                /* Second row: -1 shift, 1 5 9 13 */
                j = state[13];
                state[13] = rijndael_inv_sbox[state[9]];
                state[9] = rijndael_inv_sbox[state[5]];
                state[5] = rijndael_inv_sbox[state[1]];
                state[1] = rijndael_inv_sbox[j];

                /* Third row: -2 shift, 2 6 10 14 */
                j = state[2];
                state[2] = rijndael_inv_sbox[state[10]];
                state[10] = rijndael_inv_sbox[j];
                j = state[6];
                state[6] = rijndael_inv_sbox[state[14]];
                state[14] = rijndael_inv_sbox[j];

                /* Fourth row: -3 shift, 3 7 11 15 */
                j = state[3];
                state[3] = rijndael_inv_sbox[state[7]];
                state[7] = rijndael_inv_sbox[state[11]];
                state[11] = rijndael_inv_sbox[state[15]];
                state[15] = rijndael_inv_sbox[j];

                /* get_inv_round_key(i); */

                for (j = 15; j > 3; j--)
                        round_key[j] ^= round_key[j - 4];

                round_key[0] ^= (RC[NUMBER_OF_ROUNDS - i] ^
                    rijndael_sbox[round_key[13]]);

                round_key[1] ^= rijndael_sbox[round_key[14]];
                round_key[2] ^= rijndael_sbox[round_key[15]];
                round_key[3] ^= rijndael_sbox[round_key[12]];

                for (j = 0; j < 16; j++)
                        state[j] ^= round_key[j];
                if (i != NUMBER_OF_ROUNDS) {
                        /* inv_mix_column(); */

                        for (j = 0; j < 16; j += 4) {
                                k1 = state[j] ^ state[j + 2];
                                a02x = xtime(k1);
                                k2 = state[j + 1] ^ state[j + 3];
                                a13x = xtime(k2);

                                k1 ^= (k2 ^ xtime(state[j + 1] ^ state[j + 2]));
                                k2 = k1;

                                a02xx = xtime(a02x);
                                a13xx = xtime(a13x);


                                k1 ^= (xtime(a02xx ^ a13xx) ^ a02xx);
                                k2 ^= (xtime(a02xx ^ a13xx) ^ a13xx);

                                state[j] ^= (k1 ^ a02x);
                                state[j + 1] ^= k2;
                                state[j + 2] ^= (k1 ^ a13x);
                                state[j + 3] ^= (k2 ^ a02x ^ a13x);
                        }
                }

        }
}

uint16_t
yubikey_crc16(const uint8_t *buf, size_t buf_size)
{
        uint16_t m_crc = 0xffff;

        while (buf_size--) {
                int i, j;

                m_crc ^= (uint8_t)*buf++ & 0xFF;
                for (i = 0; i < 8; i++) {
                        j = m_crc & 1;
                        m_crc >>= 1;
                        if (j)
                                m_crc ^= 0x8408;
                }
        }
        return m_crc;
}

static const char hex_trans[] = "0123456789abcdef";

void
yubikey_hex_encode(char *dst, const char *src, size_t srcSize)
{
        while (srcSize--) {
                *dst++ = hex_trans[(*src >> 4) & 0xf];
                *dst++ = hex_trans[*src++ & 0xf];
        }
        *dst = '\0';
}

void
yubikey_hex_decode(char *dst, const char *src, size_t dstSize)
{
        char b;
        int flag = 0;
        char *p1;

        for (; *src && dstSize > 0; src++) {
                p1 = strchr(hex_trans, tolower((unsigned char)*src));
                if (p1 == NULL)
                        b = 0;
                else
                        b = (char)(p1 - hex_trans);
                if ((flag = !flag))
                        *dst = b;
                else {
                        *dst = (*dst << 4) | b;
                        dst++;
                        dstSize--;
                }
        }
        while (dstSize--)
                *dst++ = 0;
}

static const char modhex_trans[] = "cbdefghijklnrtuv";

void
yubikey_modhex_decode(char *dst, const char *src, size_t dstSize)
{
        char b;
        int flag = 0;
        char *p1;

        for (; *src && dstSize > 0; src++) {
                p1 = strchr(modhex_trans, tolower((unsigned char)*src));
                if (p1 == NULL)
                        b = 0;
                else
                        b = (char)(p1 - modhex_trans);

                if ((flag = !flag))
                        *dst = b;
                else {
                        *dst = (*dst << 4) | b;
                        dst++;
                        dstSize--;
                }
        }
        while (dstSize--)
                *dst++ = 0;
}

uint8_t
yubikey_keymap_decode(wchar_t *wpassword, char *token, int index)
{
        int c, j, found;
        for (j=0; j<YUBIKEY_TOKEN_SIZE; j++) {
                found = 0;
                for (c=0; c<16; c++) {
                        if (wpassword[j] == keymaps[index][c]) {
                                token[j] = modhex_trans[c];
                                found++;
                                break;
                        }
                }
                if (found == 0)
                        return 1;
        }
        return 0;
}

int
yubikey_parse(const uint8_t *password, const uint8_t key[YUBIKEY_KEY_SIZE],
    yubikey_token_t out, int index)
{
        wchar_t *wpassword, *pp;
        char token[YUBIKEY_TOKEN_SIZE + 1], *lc_ctype;
        size_t len;
        int rc = 0;

        if (index < 0 || index >= YUBIKEY_KEYMAP_COUNT)
                return -1;

        len = strlen(password);
        pp = wpassword = reallocarray(NULL, len + 1, sizeof(wchar_t));
        if (pp == NULL)
                return ENOMEM;

        memset(out, 0, sizeof(*out));
        memset(token, 0, YUBIKEY_TOKEN_SIZE + 1);

        lc_ctype = getenv("LC_CTYPE");
        setlocale(LC_CTYPE, lc_ctype ? lc_ctype : "C.UTF-8");
        len = mbstowcs(wpassword, password, len);
        if (len == (size_t)-1) {
                rc = errno;
                goto ret;
        }
        setlocale(LC_CTYPE, "C");

        if (len > YUBIKEY_TOKEN_SIZE)
                pp = pp + len - YUBIKEY_TOKEN_SIZE;
        if (len < YUBIKEY_TOKEN_SIZE) {
                rc = EMSGSIZE;
                goto ret;
        }

        if (yubikey_keymap_decode(pp, token, index)) {
                rc = EINVAL;
                goto ret;
        }
        yubikey_modhex_decode((void *)out, token, sizeof(*out));
        yubikey_aes_decrypt((void *)out, key);

ret:
        freezero(wpassword, (len + 1) * sizeof(wchar_t));
        return rc;
}