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/* printable key IDs, for libreswan
*
* Copyright (C) 2002 Henry Spencer.
* Copyright (C) 2020 Andrew Cagney
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Library General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <https://www.gnu.org/licenses/lgpl-2.1.txt>.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
* License for more details.
*/
#include <string.h>
#include "keyid.h"
#include "ttodata.h" /* for datatot() */
const keyid_t empty_keyid;
/*
* keyblobtokeyid - generate a printable key ID from an RFC 2537/3110
* key blob
*
* Current algorithm is just to use first nine base64 digits.
*/
err_t keyblob_to_keyid(const uint8_t *src, size_t srclen, keyid_t *dst)
{
/* XXX: datatot() returns number of bytes including trailing '\0' */
size_t ret = datatot(src, srclen, 64, dst->keyid, sizeof(dst->keyid));
if (ret < sizeof(dst->keyid)) {
/* how would this happen? */
return "key blob is too small";
} else {
return NULL;
}
}
/*
* splitkeytokeyid - generate a printable key ID from
* exponent/modulus pair
*
* Just constructs the beginnings of a key blob and calls
* keyblobtoid().
*/
err_t splitkey_to_keyid(const uint8_t *e, size_t elen,
const uint8_t *m, size_t mlen,
keyid_t *dst)
{
/* form the leading few bytes of the raw keyblob */
uint8_t keyblob[sizeof(keyid_t)]; /* ample room */
uint8_t *const blob_end = keyblob + sizeof(keyblob);
uint8_t *p = keyblob;
/* start with length of e; assume that it fits */
if (elen <= 0xff) {
/* one byte */
*p++ = elen;
} else if (elen <= 0xffff) {
/* two bytes */
*p++ = 0;
*p++ = (elen >> 8) & 0xff;
*p++ = elen & 0xff;
} else {
*dst = empty_keyid;
return "unrepresentable exponent length";
}
/* append as much of e as fits */
while (elen > 0 && p < blob_end) {
*p++ = *e++;
elen--;
}
/* append as much of m as fits */
while (mlen > 0 && p < blob_end) {
*p++ = *m++;
mlen--;
}
return keyblob_to_keyid(keyblob, p - keyblob, dst);
}
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