2 * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file crypt.c Openssl-based encryption/decryption routines. */
11 #include <sys/types.h>
12 #include <sys/socket.h>
13 #include <openssl/rand.h>
14 #include <openssl/err.h>
15 #include <openssl/rc4.h>
16 #include <openssl/pem.h>
17 #include <openssl/sha.h>
18 #include <openssl/bn.h>
25 #include "crypt_backend.h"
27 struct asymmetric_key {
31 void get_random_bytes_or_die(unsigned char *buf, int num)
35 /* RAND_bytes() returns 1 on success, 0 otherwise. */
36 if (RAND_bytes(buf, num) == 1)
38 err = ERR_get_error();
39 PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
44 * Read 64 bytes from /dev/urandom and adds them to the SSL PRNG. Seed the PRNG
45 * used by random() with a random seed obtained from SSL. If /dev/random is not
46 * readable the function calls exit().
48 * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
49 * random(3), \ref para_random().
51 void init_random_seed_or_die(void)
53 int seed, ret = RAND_load_file("/dev/urandom", 64);
56 PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
59 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
63 static EVP_PKEY *load_key(const char *file, int private)
66 EVP_PKEY *pkey = NULL;
67 int ret = check_key_file(file, private);
70 PARA_ERROR_LOG("%s\n", para_strerror(-ret));
73 key = BIO_new(BIO_s_file());
76 if (BIO_read_filename(key, file) > 0) {
77 if (private == LOAD_PRIVATE_KEY)
78 pkey = PEM_read_bio_PrivateKey(key, NULL, NULL, NULL);
80 pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);
86 static int get_openssl_key(const char *key_file, RSA **rsa, int private)
88 EVP_PKEY *key = load_key(key_file, private);
91 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
93 *rsa = EVP_PKEY_get1_RSA(key);
97 return RSA_size(*rsa);
101 * The public key loading functions below were inspired by corresponding code
102 * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
103 * Finland. However, not much of the original code remains.
106 static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
108 const unsigned char *p = buf, *end = buf + len;
116 bnsize = read_ssh_u32(p);
117 PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
121 if (p + bnsize > end)
125 bn = BN_bin2bn(p, bnsize, NULL);
132 static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
136 const unsigned char *p = blob, *end = blob + blen;
141 ret = read_bignum(p, end - p, &rsa->e);
145 ret = read_bignum(p, end - p, &rsa->n);
156 int get_asymmetric_key(const char *key_file, int private,
157 struct asymmetric_key **result)
159 struct asymmetric_key *key = NULL;
161 unsigned char *blob = NULL;
162 size_t map_size, blob_size, decoded_size;
166 key = para_malloc(sizeof(*key));
168 ret = get_openssl_key(key_file, &key->rsa, LOAD_PRIVATE_KEY);
171 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
174 ret = is_ssh_rsa_key(map, map_size);
176 ret = para_munmap(map, map_size);
180 ret = get_openssl_key(key_file, &key->rsa, LOAD_PUBLIC_KEY);
184 PARA_INFO_LOG("decoding public rsa-ssh key %s\n", key_file);
185 ret = -ERRNO_TO_PARA_ERROR(EOVERFLOW);
186 if (map_size > INT_MAX / 4)
188 blob_size = 2 * map_size;
189 blob = para_malloc(blob_size);
190 ret = uudecode(cp, blob, blob_size);
194 ret = check_ssh_key_header(blob, decoded_size);
197 ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
200 ret = RSA_size(key->rsa);
202 ret2 = para_munmap(map, map_size);
203 if (ret >= 0 && ret2 < 0)
208 PARA_ERROR_LOG("key %s: %s\n", key_file, para_strerror(-ret));
215 void free_asymmetric_key(struct asymmetric_key *key)
223 int priv_decrypt(const char *key_file, unsigned char *outbuf,
224 unsigned char *inbuf, int inlen)
226 struct asymmetric_key *priv;
231 ret = get_asymmetric_key(key_file, LOAD_PRIVATE_KEY, &priv);
235 * RSA is vulnerable to timing attacks. Generate a random blinding
236 * factor to protect against this kind of attack.
239 if (RSA_blinding_on(priv->rsa, NULL) == 0)
241 ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
242 RSA_PKCS1_OAEP_PADDING);
243 RSA_blinding_off(priv->rsa);
247 free_asymmetric_key(priv);
251 int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
252 unsigned len, unsigned char *outbuf)
254 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
258 ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
259 RSA_PKCS1_OAEP_PADDING);
260 return ret < 0? -E_ENCRYPT : ret;
263 struct stream_cipher {
267 struct stream_cipher *sc_new(const unsigned char *data, int len)
269 struct stream_cipher *sc = para_malloc(sizeof(*sc));
270 RC4_set_key(&sc->key, len, data);
274 void sc_free(struct stream_cipher *sc)
280 * The RC4() implementation of openssl apparently reads and writes data in
281 * blocks of 8 bytes. So we have to make sure our buffer sizes are a multiple
286 int sc_send_bin_buffer(struct stream_cipher_context *scc, char *buf,
291 static unsigned char remainder[RC4_ALIGN];
292 size_t l1 = ROUND_DOWN(len, RC4_ALIGN), l2 = ROUND_UP(len, RC4_ALIGN);
295 tmp = para_malloc(l2);
296 RC4(&scc->send->key, l1, (const unsigned char *)buf, tmp);
298 memcpy(remainder, buf + l1, len - l1);
299 RC4(&scc->send->key, len - l1, remainder, tmp + l1);
301 ret = write_all(scc->fd, (char *)tmp, &len);
306 int sc_recv_bin_buffer(struct stream_cipher_context *scc, char *buf,
309 unsigned char *tmp = para_malloc(size);
310 ssize_t ret = recv(scc->fd, tmp, size, 0);
313 RC4(&scc->recv->key, ret, tmp, (unsigned char *)buf);
315 ret = -ERRNO_TO_PARA_ERROR(errno);
320 void hash_function(const char *data, unsigned long len, unsigned char *hash)
324 SHA1_Update(&c, data, len);
325 SHA1_Final(hash, &c);