mirror of https://gitlab.com/octospacc/SmolOTP.git
126 lines
4.2 KiB
C
126 lines
4.2 KiB
C
/*
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*
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* TOTP: Time-Based One-Time Password Algorithm
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* Copyright (c) 2017, fmount <fmount9@autistici.org>
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*
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* This software is distributed under MIT License
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*
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* Compute the hmac using openssl library.
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* SHA-1 engine is used by default, but you can pass another one,
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*
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* e.g EVP_md5(), EVP_sha224, EVP_sha512, etc
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*
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*/
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#include "utils.h"
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static const int8_t base32_vals[256] = {
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// This map cheats and interprets:
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// - the numeral zero as the letter "O" as in oscar
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// - the numeral one as the letter "L" as in lima
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// - the numeral eight as the letter "B" as in bravo
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// 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x00
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x10
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x20
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14, 11, 26, 27, 28, 29, 30, 31, 1, -1, -1, -1, -1, 0, -1, -1, // 0x30
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-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 0x40
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, // 0x50
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-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 0x60
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, -1, -1, -1, -1, // 0x70
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x80
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x90
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xA0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xB0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xC0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xD0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xE0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xF0
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};
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int validate_b32key(char *k, size_t len, size_t pos)
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{
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// validates base32 key
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if (((len & 0xF) != 0) && ((len & 0xF) != 8))
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return 1;
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for (pos = 0; (pos < len); pos++) {
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if (base32_vals[k[pos]] == -1)
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return 1;
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if (k[pos] == '=') {
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if (((pos & 0xF) == 0) || ((pos & 0xF) == 8))
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return(1);
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if ((len - pos) > 6)
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return 1;
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switch (pos % 8) {
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case 2:
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case 4:
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case 5:
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case 7:
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break;
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default:
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return 1;
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}
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for ( ; (pos < len); pos++) {
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if (k[pos] != '=')
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return 1;
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}
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}
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}
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return 0;
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}
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size_t decode_b32key(uint8_t **k, size_t len)
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{
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size_t keylen;
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size_t pos;
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// decodes base32 secret key
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keylen = 0;
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for (pos = 0; pos <= (len - 8); pos += 8) {
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// MSB is Most Significant Bits (0x80 == 10000000 ~= MSB)
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// MB is middle bits (0x7E == 01111110 ~= MB)
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// LSB is Least Significant Bits (0x01 == 00000001 ~= LSB)
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// byte 0
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(*k)[keylen+0] = (base32_vals[(*k)[pos+0]] << 3) & 0xF8; // 5 MSB
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(*k)[keylen+0] |= (base32_vals[(*k)[pos+1]] >> 2) & 0x07; // 3 LSB
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if ((*k)[pos+2] == '=') {
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keylen += 1;
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break;
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}
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// byte 1
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(*k)[keylen+1] = (base32_vals[(*k)[pos+1]] << 6) & 0xC0; // 2 MSB
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(*k)[keylen+1] |= (base32_vals[(*k)[pos+2]] << 1) & 0x3E; // 5 MB
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(*k)[keylen+1] |= (base32_vals[(*k)[pos+3]] >> 4) & 0x01; // 1 LSB
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if ((*k)[pos+4] == '=') {
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keylen += 2;
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break;
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}
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// byte 2
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(*k)[keylen+2] = (base32_vals[(*k)[pos+3]] << 4) & 0xF0; // 4 MSB
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(*k)[keylen+2] |= (base32_vals[(*k)[pos+4]] >> 1) & 0x0F; // 4 LSB
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if ((*k)[pos+5] == '=') {
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keylen += 3;
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break;
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}
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// byte 3
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(*k)[keylen+3] = (base32_vals[(*k)[pos+4]] << 7) & 0x80; // 1 MSB
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(*k)[keylen+3] |= (base32_vals[(*k)[pos+5]] << 2) & 0x7C; // 5 MB
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(*k)[keylen+3] |= (base32_vals[(*k)[pos+6]] >> 3) & 0x03; // 2 LSB
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if ((*k)[pos+7] == '=') {
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keylen += 4;
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break;
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}
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// byte 4
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(*k)[keylen+4] = (base32_vals[(*k)[pos+6]] << 5) & 0xE0; // 3 MSB
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(*k)[keylen+4] |= (base32_vals[(*k)[pos+7]] >> 0) & 0x1F; // 5 LSB
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keylen += 5;
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}
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(*k)[keylen] = 0;
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return keylen;
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}
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