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/* $OpenBSD: ssh-ed25519.c,v 1.2 2014/02/02 03:44:31 djm Exp $ */
/*
* Copyright (c) 2013 Markus Friedl <markus@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include "crypto_api.h"
#include <string.h>
#include <stdarg.h>
#include "xmalloc.h"
#include "log.h"
#include "buffer.h"
#include "key.h"
#include "ssh.h"
int
ssh_ed25519_sign(const Key *key, u_char **sigp, u_int *lenp,
const u_char *data, u_int datalen)
{
u_char *sig;
u_int slen, len;
unsigned long long smlen;
int ret;
Buffer b;
if (key == NULL || key_type_plain(key->type) != KEY_ED25519 ||
key->ed25519_sk == NULL) {
error("%s: no ED25519 key", __func__);
return -1;
}
smlen = slen = datalen + crypto_sign_ed25519_BYTES;
sig = xmalloc(slen);
if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen,
key->ed25519_sk)) != 0 || smlen <= datalen) {
error("%s: crypto_sign_ed25519 failed: %d", __func__, ret);
free(sig);
return -1;
}
/* encode signature */
buffer_init(&b);
buffer_put_cstring(&b, "ssh-ed25519");
buffer_put_string(&b, sig, smlen - datalen);
len = buffer_len(&b);
if (lenp != NULL)
*lenp = len;
if (sigp != NULL) {
*sigp = xmalloc(len);
memcpy(*sigp, buffer_ptr(&b), len);
}
buffer_free(&b);
explicit_bzero(sig, slen);
free(sig);
return 0;
}
int
ssh_ed25519_verify(const Key *key, const u_char *signature, u_int signaturelen,
const u_char *data, u_int datalen)
{
Buffer b;
char *ktype;
u_char *sigblob, *sm, *m;
u_int len;
unsigned long long smlen, mlen;
int rlen, ret;
if (key == NULL || key_type_plain(key->type) != KEY_ED25519 ||
key->ed25519_pk == NULL) {
error("%s: no ED25519 key", __func__);
return -1;
}
buffer_init(&b);
buffer_append(&b, signature, signaturelen);
ktype = buffer_get_cstring(&b, NULL);
if (strcmp("ssh-ed25519", ktype) != 0) {
error("%s: cannot handle type %s", __func__, ktype);
buffer_free(&b);
free(ktype);
return -1;
}
free(ktype);
sigblob = buffer_get_string(&b, &len);
rlen = buffer_len(&b);
buffer_free(&b);
if (rlen != 0) {
error("%s: remaining bytes in signature %d", __func__, rlen);
free(sigblob);
return -1;
}
if (len > crypto_sign_ed25519_BYTES) {
error("%s: len %u > crypto_sign_ed25519_BYTES %u", __func__,
len, crypto_sign_ed25519_BYTES);
free(sigblob);
return -1;
}
smlen = len + datalen;
sm = xmalloc(smlen);
memcpy(sm, sigblob, len);
memcpy(sm+len, data, datalen);
mlen = smlen;
m = xmalloc(mlen);
if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
key->ed25519_pk)) != 0) {
debug2("%s: crypto_sign_ed25519_open failed: %d",
__func__, ret);
}
if (ret == 0 && mlen != datalen) {
debug2("%s: crypto_sign_ed25519_open "
"mlen != datalen (%llu != %u)", __func__, mlen, datalen);
ret = -1;
}
/* XXX compare 'm' and 'data' ? */
explicit_bzero(sigblob, len);
explicit_bzero(sm, smlen);
explicit_bzero(m, smlen); /* NB. mlen may be invalid if ret != 0 */
free(sigblob);
free(sm);
free(m);
debug("%s: signature %scorrect", __func__, (ret != 0) ? "in" : "");
/* translate return code carefully */
return (ret == 0) ? 1 : -1;
}
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