view sk-ed25519.c @ 1855:35d504d59c05

Implement server-side support for sk-ecdsa U2F-backed keys (#142) * Implement server-side support for sk-ecdsa U2F-backed keys * Fix out-of-bounds read on normal ecdsa-sha2-[identifier] keys * Fix one more potential out-of-bounds read * Check if nistp256 curve is used in sk-ecdsa-sha2- key It's the only allowed curve per PROTOCOL.u2f specification * Implement server-side support for sk-ed25519 FIDO2-backed keys * Keys with type sk-* make no sense as host keys, so they should be disabled * fix typo * Make sk-ecdsa call buf_ecdsa_verify This reduces code duplication, the SK code just handles the different message format. * Reduce sk specific code The application id can be stored in signkey, then we don't need to call sk-specific functions from svr-authpubkey * Remove debugging output, which causes compilation errors with DEBUG_TRACE disabled * Proper cleanup of sk_app Co-authored-by: Matt Johnston <[email protected]>
author egor-duda <egor-duda@users.noreply.github.com>
date Sat, 22 Jan 2022 16:53:04 +0300
parents
children 333688ec53d0
line wrap: on
line source

#include "includes.h"

#if DROPBEAR_SK_ED25519

#include "dbutil.h"
#include "buffer.h"
#include "curve25519.h"
#include "ed25519.h"

int buf_sk_ed25519_verify(buffer *buf, const dropbear_ed25519_key *key, const buffer *data_buf, const char* app, unsigned int applen) {

	int ret = DROPBEAR_FAILURE;
	unsigned char *s;
	unsigned long slen;
	hash_state hs;
	unsigned char hash[SHA256_HASH_SIZE];
	buffer *sk_buffer = NULL;
	unsigned char flags;
	unsigned int counter;

	TRACE(("enter buf_sk_ed25519_verify"))
	dropbear_assert(key != NULL);

	slen = buf_getint(buf);
	if (slen != 64 || buf->len - buf->pos < slen) {
		TRACE(("leave buf_sk_ed25519_verify: bad size"))
		goto out;
	}
	s = buf_getptr(buf, slen);
	buf_incrpos(buf, slen);

	flags = buf_getbyte (buf);
	counter = buf_getint (buf);
	sk_buffer = buf_new (2*SHA256_HASH_SIZE+5);
	sha256_init (&hs);
	sha256_process (&hs, app, applen);
	sha256_done (&hs, hash);
	buf_putbytes (sk_buffer, hash, sizeof (hash));
	buf_putbyte (sk_buffer, flags);
	buf_putint (sk_buffer, counter);
	sha256_init (&hs);
	sha256_process (&hs, data_buf->data, data_buf->len);
	sha256_done (&hs, hash);
	buf_putbytes (sk_buffer, hash, sizeof (hash));

	if (dropbear_ed25519_verify(sk_buffer->data, sk_buffer->len,
				    s, slen, key->pub) == 0) {
		/* signature is valid */
		TRACE(("leave buf_sk_ed25519_verify: success!"))
		ret = DROPBEAR_SUCCESS;
	}

out:
	if (sk_buffer) {
		buf_free(sk_buffer);
	}
	TRACE(("leave buf_sk_ed25519_verify: ret %d", ret))
	return ret;
}

#endif /* DROPBEAR_SK_ED25519 */