- markus@cvs.openbsd.org 2013/12/06 13:34:54
[authfile.c authfile.h cipher.c cipher.h key.c packet.c ssh-agent.c]
[ssh-keygen.c PROTOCOL.key] new private key format, bcrypt as KDF by
default; details in PROTOCOL.key; feedback and lots help from djm;
ok djm@
diff --git a/authfile.c b/authfile.c
index d0c1089..e38a3dd 100644
--- a/authfile.c
+++ b/authfile.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: authfile.c,v 1.98 2013/11/21 00:45:43 djm Exp $ */
+/* $OpenBSD: authfile.c,v 1.99 2013/12/06 13:34:54 markus Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -13,7 +13,7 @@
* called by a name other than "ssh" or "Secure Shell".
*
*
- * Copyright (c) 2000 Markus Friedl. All rights reserved.
+ * Copyright (c) 2000, 2013 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@@ -58,6 +58,8 @@
#include <string.h>
#include <unistd.h>
+#include <util.h>
+
#include "xmalloc.h"
#include "cipher.h"
#include "buffer.h"
@@ -68,6 +70,16 @@
#include "rsa.h"
#include "misc.h"
#include "atomicio.h"
+#include "uuencode.h"
+
+/* openssh private key file format */
+#define MARK_BEGIN "-----BEGIN OPENSSH PRIVATE KEY-----\n"
+#define MARK_END "-----END OPENSSH PRIVATE KEY-----\n"
+#define KDFNAME "bcrypt"
+#define AUTH_MAGIC "openssh-key-v1"
+#define SALT_LEN 16
+#define DEFAULT_CIPHERNAME "aes256-cbc"
+#define DEFAULT_ROUNDS 16
#define MAX_KEY_FILE_SIZE (1024 * 1024)
@@ -75,6 +87,333 @@
static const char authfile_id_string[] =
"SSH PRIVATE KEY FILE FORMAT 1.1\n";
+static int
+key_private_to_blob2(Key *prv, Buffer *blob, const char *passphrase,
+ const char *comment, const char *ciphername, int rounds)
+{
+ u_char *key, *cp, salt[SALT_LEN];
+ size_t keylen, ivlen, blocksize, authlen;
+ u_int len, check;
+ int i, n;
+ const Cipher *c;
+ Buffer encoded, b, kdf;
+ CipherContext ctx;
+ const char *kdfname = KDFNAME;
+
+ if (rounds <= 0)
+ rounds = DEFAULT_ROUNDS;
+ if (passphrase == NULL || !strlen(passphrase)) {
+ ciphername = "none";
+ kdfname = "none";
+ } else if (ciphername == NULL)
+ ciphername = DEFAULT_CIPHERNAME;
+ else if (cipher_number(ciphername) != SSH_CIPHER_SSH2)
+ fatal("invalid cipher");
+
+ if ((c = cipher_by_name(ciphername)) == NULL)
+ fatal("unknown cipher name");
+ buffer_init(&kdf);
+ blocksize = cipher_blocksize(c);
+ keylen = cipher_keylen(c);
+ ivlen = cipher_ivlen(c);
+ authlen = cipher_authlen(c);
+ key = xcalloc(1, keylen + ivlen);
+ if (strcmp(kdfname, "none") != 0) {
+ arc4random_buf(salt, SALT_LEN);
+ if (bcrypt_pbkdf(passphrase, strlen(passphrase),
+ salt, SALT_LEN, key, keylen + ivlen, rounds) < 0)
+ fatal("bcrypt_pbkdf failed");
+ buffer_put_string(&kdf, salt, SALT_LEN);
+ buffer_put_int(&kdf, rounds);
+ }
+ cipher_init(&ctx, c, key, keylen, key + keylen , ivlen, 1);
+ memset(key, 0, keylen + ivlen);
+ free(key);
+
+ buffer_init(&encoded);
+ buffer_append(&encoded, AUTH_MAGIC, sizeof(AUTH_MAGIC));
+ buffer_put_cstring(&encoded, ciphername);
+ buffer_put_cstring(&encoded, kdfname);
+ buffer_put_string(&encoded, buffer_ptr(&kdf), buffer_len(&kdf));
+ buffer_put_int(&encoded, 1); /* number of keys */
+ key_to_blob(prv, &cp, &len); /* public key */
+ buffer_put_string(&encoded, cp, len);
+
+ memset(cp, 0, len);
+ free(cp);
+
+ buffer_free(&kdf);
+
+ /* set up the buffer that will be encrypted */
+ buffer_init(&b);
+
+ /* Random check bytes */
+ check = arc4random();
+ buffer_put_int(&b, check);
+ buffer_put_int(&b, check);
+
+ /* append private key and comment*/
+ key_private_serialize(prv, &b);
+ buffer_put_cstring(&b, comment);
+
+ /* padding */
+ i = 0;
+ while (buffer_len(&b) % blocksize)
+ buffer_put_char(&b, ++i & 0xff);
+
+ /* length */
+ buffer_put_int(&encoded, buffer_len(&b));
+
+ /* encrypt */
+ cp = buffer_append_space(&encoded, buffer_len(&b) + authlen);
+ if (cipher_crypt(&ctx, 0, cp, buffer_ptr(&b), buffer_len(&b), 0,
+ authlen) != 0)
+ fatal("%s: cipher_crypt failed", __func__);
+ buffer_free(&b);
+ cipher_cleanup(&ctx);
+
+ /* uuencode */
+ len = 2 * buffer_len(&encoded);
+ cp = xmalloc(len);
+ n = uuencode(buffer_ptr(&encoded), buffer_len(&encoded),
+ (char *)cp, len);
+ if (n < 0)
+ fatal("%s: uuencode", __func__);
+
+ buffer_clear(blob);
+ buffer_append(blob, MARK_BEGIN, sizeof(MARK_BEGIN) - 1);
+ for (i = 0; i < n; i++) {
+ buffer_put_char(blob, cp[i]);
+ if (i % 70 == 69)
+ buffer_put_char(blob, '\n');
+ }
+ if (i % 70 != 69)
+ buffer_put_char(blob, '\n');
+ buffer_append(blob, MARK_END, sizeof(MARK_END) - 1);
+ free(cp);
+
+ return buffer_len(blob);
+}
+
+static Key *
+key_parse_private2(Buffer *blob, int type, const char *passphrase,
+ char **commentp)
+{
+ u_char *key = NULL, *cp, *salt = NULL, pad, last;
+ char *comment = NULL, *ciphername = NULL, *kdfname = NULL, *kdfp;
+ u_int keylen = 0, ivlen, blocksize, slen, klen, len, rounds, nkeys;
+ u_int check1, check2, m1len, m2len;
+ size_t authlen;
+ const Cipher *c;
+ Buffer b, encoded, copy, kdf;
+ CipherContext ctx;
+ Key *k = NULL;
+ int dlen, ret, i;
+
+ buffer_init(&b);
+ buffer_init(&kdf);
+ buffer_init(&encoded);
+ buffer_init(©);
+
+ /* uudecode */
+ m1len = sizeof(MARK_BEGIN) - 1;
+ m2len = sizeof(MARK_END) - 1;
+ cp = buffer_ptr(blob);
+ len = buffer_len(blob);
+ if (len < m1len || memcmp(cp, MARK_BEGIN, m1len)) {
+ debug("%s: missing begin marker", __func__);
+ goto out;
+ }
+ cp += m1len;
+ len -= m1len;
+ while (len) {
+ if (*cp != '\n' && *cp != '\r')
+ buffer_put_char(&encoded, *cp);
+ last = *cp;
+ len--;
+ cp++;
+ if (last == '\n') {
+ if (len >= m2len && !memcmp(cp, MARK_END, m2len)) {
+ buffer_put_char(&encoded, '\0');
+ break;
+ }
+ }
+ }
+ if (!len) {
+ debug("%s: no end marker", __func__);
+ goto out;
+ }
+ len = buffer_len(&encoded);
+ if ((cp = buffer_append_space(©, len)) == NULL) {
+ error("%s: buffer_append_space", __func__);
+ goto out;
+ }
+ if ((dlen = uudecode(buffer_ptr(&encoded), cp, len)) < 0) {
+ error("%s: uudecode failed", __func__);
+ goto out;
+ }
+ if ((u_int)dlen > len) {
+ error("%s: crazy uudecode length %d > %u", __func__, dlen, len);
+ goto out;
+ }
+ buffer_consume_end(©, len - dlen);
+ if (buffer_len(©) < sizeof(AUTH_MAGIC) ||
+ memcmp(buffer_ptr(©), AUTH_MAGIC, sizeof(AUTH_MAGIC))) {
+ error("%s: bad magic", __func__);
+ goto out;
+ }
+ buffer_consume(©, sizeof(AUTH_MAGIC));
+
+ ciphername = buffer_get_cstring_ret(©, NULL);
+ if (ciphername == NULL ||
+ (c = cipher_by_name(ciphername)) == NULL) {
+ error("%s: unknown cipher name", __func__);
+ goto out;
+ }
+ if ((passphrase == NULL || !strlen(passphrase)) &&
+ strcmp(ciphername, "none") != 0) {
+ /* passphrase required */
+ goto out;
+ }
+ kdfname = buffer_get_cstring_ret(©, NULL);
+ if (kdfname == NULL ||
+ (!strcmp(kdfname, "none") && !strcmp(kdfname, "bcrypt"))) {
+ error("%s: unknown kdf name", __func__);
+ goto out;
+ }
+ if (!strcmp(kdfname, "none") && strcmp(ciphername, "none") != 0) {
+ error("%s: cipher %s requires kdf", __func__, ciphername);
+ goto out;
+ }
+ /* kdf options */
+ kdfp = buffer_get_string_ptr_ret(©, &klen);
+ if (kdfp == NULL) {
+ error("%s: kdf options not set", __func__);
+ goto out;
+ }
+ if (klen > 0) {
+ if ((cp = buffer_append_space(&kdf, klen)) == NULL) {
+ error("%s: kdf alloc failed", __func__);
+ goto out;
+ }
+ memcpy(cp, kdfp, klen);
+ }
+ /* number of keys */
+ if (buffer_get_int_ret(&nkeys, ©) < 0) {
+ error("%s: key counter missing", __func__);
+ goto out;
+ }
+ if (nkeys != 1) {
+ error("%s: only one key supported", __func__);
+ goto out;
+ }
+ /* pubkey */
+ if ((cp = buffer_get_string_ret(©, &len)) == NULL) {
+ error("%s: pubkey not found", __func__);
+ goto out;
+ }
+ free(cp); /* XXX check pubkey against decrypted private key */
+
+ /* size of encrypted key blob */
+ len = buffer_get_int(©);
+ blocksize = cipher_blocksize(c);
+ authlen = cipher_authlen(c);
+ if (len < blocksize) {
+ error("%s: encrypted data too small", __func__);
+ goto out;
+ }
+ if (len % blocksize) {
+ error("%s: length not multiple of blocksize", __func__);
+ goto out;
+ }
+
+ /* setup key */
+ keylen = cipher_keylen(c);
+ ivlen = cipher_ivlen(c);
+ key = xcalloc(1, keylen + ivlen);
+ if (!strcmp(kdfname, "bcrypt")) {
+ if ((salt = buffer_get_string_ret(&kdf, &slen)) == NULL) {
+ error("%s: salt not set", __func__);
+ goto out;
+ }
+ if (buffer_get_int_ret(&rounds, &kdf) < 0) {
+ error("%s: rounds not set", __func__);
+ goto out;
+ }
+ if (bcrypt_pbkdf(passphrase, strlen(passphrase), salt, slen,
+ key, keylen + ivlen, rounds) < 0) {
+ error("%s: bcrypt_pbkdf failed", __func__);
+ goto out;
+ }
+ }
+
+ cp = buffer_append_space(&b, len);
+ cipher_init(&ctx, c, key, keylen, key + keylen, ivlen, 0);
+ ret = cipher_crypt(&ctx, 0, cp, buffer_ptr(©), len, 0, authlen);
+ cipher_cleanup(&ctx);
+ buffer_consume(©, len);
+
+ /* fail silently on decryption errors */
+ if (ret != 0) {
+ debug("%s: decrypt failed", __func__);
+ goto out;
+ }
+
+ if (buffer_len(©) != 0) {
+ error("%s: key blob has trailing data (len = %u)", __func__,
+ buffer_len(©));
+ goto out;
+ }
+
+ /* check bytes */
+ if (buffer_get_int_ret(&check1, &b) < 0 ||
+ buffer_get_int_ret(&check2, &b) < 0) {
+ error("check bytes missing");
+ goto out;
+ }
+ if (check1 != check2) {
+ debug("%s: decrypt failed: 0x%08x != 0x%08x", __func__,
+ check1, check2);
+ goto out;
+ }
+
+ k = key_private_deserialize(&b);
+
+ /* comment */
+ comment = buffer_get_cstring_ret(&b, NULL);
+
+ i = 0;
+ while (buffer_len(&b)) {
+ if (buffer_get_char_ret(&pad, &b) == -1 ||
+ pad != (++i & 0xff)) {
+ error("%s: bad padding", __func__);
+ key_free(k);
+ k = NULL;
+ goto out;
+ }
+ }
+
+ if (k && commentp) {
+ *commentp = comment;
+ comment = NULL;
+ }
+
+ /* XXX decode pubkey and check against private */
+ out:
+ free(ciphername);
+ free(kdfname);
+ free(salt);
+ free(comment);
+ if (key)
+ memset(key, 0, keylen + ivlen);
+ free(key);
+ buffer_free(&encoded);
+ buffer_free(©);
+ buffer_free(&kdf);
+ buffer_free(&b);
+ return k;
+}
+
/*
* Serialises the authentication (private) key to a blob, encrypting it with
* passphrase. The identification of the blob (lowest 64 bits of n) will
@@ -149,8 +488,9 @@
cipher_set_key_string(&ciphercontext, cipher, passphrase,
CIPHER_ENCRYPT);
- cipher_crypt(&ciphercontext, 0, cp,
- buffer_ptr(&buffer), buffer_len(&buffer), 0, 0);
+ if (cipher_crypt(&ciphercontext, 0, cp,
+ buffer_ptr(&buffer), buffer_len(&buffer), 0, 0) != 0)
+ fatal("%s: cipher_crypt failed", __func__);
cipher_cleanup(&ciphercontext);
memset(&ciphercontext, 0, sizeof(ciphercontext));
@@ -239,7 +579,8 @@
/* Serialise "key" to buffer "blob" */
static int
key_private_to_blob(Key *key, Buffer *blob, const char *passphrase,
- const char *comment)
+ const char *comment, int force_new_format, const char *new_format_cipher,
+ int new_format_rounds)
{
switch (key->type) {
case KEY_RSA1:
@@ -247,6 +588,10 @@
case KEY_DSA:
case KEY_ECDSA:
case KEY_RSA:
+ if (force_new_format) {
+ return key_private_to_blob2(key, blob, passphrase,
+ comment, new_format_cipher, new_format_rounds);
+ }
return key_private_pem_to_blob(key, blob, passphrase, comment);
default:
error("%s: cannot save key type %d", __func__, key->type);
@@ -256,13 +601,15 @@
int
key_save_private(Key *key, const char *filename, const char *passphrase,
- const char *comment)
+ const char *comment, int force_new_format, const char *new_format_cipher,
+ int new_format_rounds)
{
Buffer keyblob;
int success = 0;
buffer_init(&keyblob);
- if (!key_private_to_blob(key, &keyblob, passphrase, comment))
+ if (!key_private_to_blob(key, &keyblob, passphrase, comment,
+ force_new_format, new_format_cipher, new_format_rounds))
goto out;
if (!key_save_private_blob(&keyblob, filename))
goto out;
@@ -473,8 +820,9 @@
/* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
cipher_set_key_string(&ciphercontext, cipher, passphrase,
CIPHER_DECRYPT);
- cipher_crypt(&ciphercontext, 0, cp,
- buffer_ptr(©), buffer_len(©), 0, 0);
+ if (cipher_crypt(&ciphercontext, 0, cp,
+ buffer_ptr(©), buffer_len(©), 0, 0) != 0)
+ fatal("%s: cipher_crypt failed", __func__);
cipher_cleanup(&ciphercontext);
memset(&ciphercontext, 0, sizeof(ciphercontext));
buffer_free(©);
@@ -641,6 +989,8 @@
key_parse_private_type(Buffer *blob, int type, const char *passphrase,
char **commentp)
{
+ Key *k;
+
switch (type) {
case KEY_RSA1:
return key_parse_private_rsa1(blob, passphrase, commentp);
@@ -648,6 +998,8 @@
case KEY_ECDSA:
case KEY_RSA:
case KEY_UNSPEC:
+ if ((k = key_parse_private2(blob, type, passphrase, commentp)))
+ return k;
return key_parse_private_pem(blob, type, passphrase, commentp);
default:
error("%s: cannot parse key type %d", __func__, type);
@@ -943,4 +1295,3 @@
fclose(f);
return ret;
}
-