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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "memory-util.h"
#include "random-util.h"
#include "recovery-key.h"
const char modhex_alphabet[16] = {
'c', 'b', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'n', 'r', 't', 'u', 'v'
};
int decode_modhex_char(char x) {
for (size_t i = 0; i < ELEMENTSOF(modhex_alphabet); i++)
/* Check both upper and lowercase */
if (modhex_alphabet[i] == x || (modhex_alphabet[i] - 32) == x)
return i;
return -EINVAL;
}
int normalize_recovery_key(const char *password, char **ret) {
_cleanup_(erase_and_freep) char *mangled = NULL;
size_t l;
assert(password);
assert(ret);
l = strlen(password);
if (!IN_SET(l,
RECOVERY_KEY_MODHEX_RAW_LENGTH*2, /* syntax without dashes */
RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1)) /* syntax with dashes */
return -EINVAL;
mangled = new(char, RECOVERY_KEY_MODHEX_FORMATTED_LENGTH);
if (!mangled)
return -ENOMEM;
for (size_t i = 0, j = 0; i < RECOVERY_KEY_MODHEX_RAW_LENGTH; i++) {
size_t k;
int a, b;
if (l == RECOVERY_KEY_MODHEX_RAW_LENGTH*2)
/* Syntax without dashes */
k = i * 2;
else {
/* Syntax with dashes */
assert(l == RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1);
k = i * 2 + i / 4;
if (i > 0 && i % 4 == 0 && password[k-1] != '-')
return -EINVAL;
}
a = decode_modhex_char(password[k]);
if (a < 0)
return -EINVAL;
b = decode_modhex_char(password[k+1]);
if (b < 0)
return -EINVAL;
mangled[j++] = modhex_alphabet[a];
mangled[j++] = modhex_alphabet[b];
if (i % 4 == 3)
mangled[j++] = '-';
}
mangled[RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1] = 0;
*ret = TAKE_PTR(mangled);
return 0;
}
int make_recovery_key(char **ret) {
_cleanup_(erase_and_freep) char *formatted = NULL;
_cleanup_(erase_and_freep) uint8_t *key = NULL;
size_t j = 0;
int r;
assert(ret);
key = new(uint8_t, RECOVERY_KEY_MODHEX_RAW_LENGTH);
if (!key)
return -ENOMEM;
r = crypto_random_bytes(key, RECOVERY_KEY_MODHEX_RAW_LENGTH);
if (r < 0)
return r;
/* Let's now format it as 64 modhex chars, and after each 8 chars insert a dash */
formatted = new(char, RECOVERY_KEY_MODHEX_FORMATTED_LENGTH);
if (!formatted)
return -ENOMEM;
for (size_t i = 0; i < RECOVERY_KEY_MODHEX_RAW_LENGTH; i++) {
formatted[j++] = modhex_alphabet[key[i] >> 4];
formatted[j++] = modhex_alphabet[key[i] & 0xF];
if (i % 4 == 3)
formatted[j++] = '-';
}
assert(j == RECOVERY_KEY_MODHEX_FORMATTED_LENGTH);
assert(formatted[RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1] == '-');
formatted[RECOVERY_KEY_MODHEX_FORMATTED_LENGTH-1] = 0; /* replace final dash with a NUL */
*ret = TAKE_PTR(formatted);
return 0;
}
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