2 * Copyright (C) 2005-2013 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. */
10 #include <sys/types.h>
11 #include <sys/socket.h>
12 #include <openssl/rand.h>
13 #include <openssl/err.h>
14 #include <openssl/rc4.h>
15 #include <openssl/pem.h>
16 #include <openssl/sha.h>
17 #include <openssl/bn.h>
24 #include "crypt_backend.h"
26 struct asymmetric_key {
30 void get_random_bytes_or_die(unsigned char *buf, int num)
34 /* RAND_bytes() returns 1 on success, 0 otherwise. */
35 if (RAND_bytes(buf, num) == 1)
37 err = ERR_get_error();
38 PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
43 * Read 64 bytes from /dev/urandom and adds them to the SSL PRNG. Seed the PRNG
44 * used by random() with a random seed obtained from SSL. If /dev/random is not
45 * readable the function calls exit().
47 * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
48 * random(3), \ref para_random().
50 void init_random_seed_or_die(void)
52 int seed, ret = RAND_load_file("/dev/urandom", 64);
55 PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
58 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
62 static EVP_PKEY *load_key(const char *file, int private)
65 EVP_PKEY *pkey = NULL;
66 int ret = check_key_file(file, private);
69 PARA_ERROR_LOG("%s\n", para_strerror(-ret));
72 key = BIO_new(BIO_s_file());
75 if (BIO_read_filename(key, file) > 0) {
76 if (private == LOAD_PRIVATE_KEY)
77 pkey = PEM_read_bio_PrivateKey(key, NULL, NULL, NULL);
79 pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);
85 static int get_openssl_key(const char *key_file, RSA **rsa, int private)
87 EVP_PKEY *key = load_key(key_file, private);
90 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
92 *rsa = EVP_PKEY_get1_RSA(key);
96 return RSA_size(*rsa);
100 * The public key loading functions below were inspired by corresponding code
101 * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
102 * Finland. However, not much of the original code remains.
105 static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
107 const unsigned char *p = buf, *end = buf + len;
115 bnsize = read_ssh_u32(p);
116 PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
120 if (p + bnsize > end)
124 bn = BN_bin2bn(p, bnsize, NULL);
131 static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
135 const unsigned char *p = blob, *end = blob + blen;
140 ret = read_bignum(p, end - p, &rsa->e);
144 ret = read_bignum(p, end - p, &rsa->n);
154 int get_asymmetric_key(const char *key_file, int private,
155 struct asymmetric_key **result)
157 struct asymmetric_key *key = NULL;
159 unsigned char *blob = NULL;
160 size_t map_size, blob_size, decoded_size;
164 key = para_malloc(sizeof(*key));
166 ret = get_openssl_key(key_file, &key->rsa, LOAD_PRIVATE_KEY);
169 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
172 ret = is_ssh_rsa_key(map, map_size);
174 ret = para_munmap(map, map_size);
178 ret = get_openssl_key(key_file, &key->rsa, LOAD_PUBLIC_KEY);
182 PARA_INFO_LOG("decoding public rsa-ssh key %s\n", key_file);
183 ret = -ERRNO_TO_PARA_ERROR(EOVERFLOW);
184 if (map_size > INT_MAX / 4)
186 blob_size = 2 * map_size;
187 blob = para_malloc(blob_size);
188 ret = uudecode(cp, blob, blob_size);
192 ret = check_ssh_key_header(blob, decoded_size);
195 ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
198 ret = RSA_size(key->rsa);
200 ret2 = para_munmap(map, map_size);
201 if (ret >= 0 && ret2 < 0)
207 PARA_ERROR_LOG("key %s: %s\n", key_file, para_strerror(-ret));
214 void free_asymmetric_key(struct asymmetric_key *key)
222 int priv_decrypt(const char *key_file, unsigned char *outbuf,
223 unsigned char *inbuf, int inlen)
225 struct asymmetric_key *priv;
230 ret = get_asymmetric_key(key_file, LOAD_PRIVATE_KEY, &priv);
234 * RSA is vulnerable to timing attacks. Generate a random blinding
235 * factor to protect against this kind of attack.
238 if (RSA_blinding_on(priv->rsa, NULL) == 0)
240 ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
241 RSA_PKCS1_OAEP_PADDING);
242 RSA_blinding_off(priv->rsa);
246 free_asymmetric_key(priv);
250 int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
251 unsigned len, unsigned char *outbuf)
253 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
257 ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
258 RSA_PKCS1_OAEP_PADDING);
259 return ret < 0? -E_ENCRYPT : ret;
262 struct stream_cipher {
266 struct stream_cipher *sc_new(const unsigned char *data, int len)
268 struct stream_cipher *sc = para_malloc(sizeof(*sc));
269 RC4_set_key(&sc->key, len, data);
273 void sc_free(struct stream_cipher *sc)
279 * The RC4() implementation of openssl apparently reads and writes data in
280 * blocks of 8 bytes. So we have to make sure our buffer sizes are a multiple
285 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
287 size_t len = src->iov_len, l1, l2;
288 RC4_KEY *key = &sc->key;
291 assert(len < ((typeof(src->iov_len))-1) / 2);
292 l1 = ROUND_DOWN(len, RC4_ALIGN);
293 l2 = ROUND_UP(len, RC4_ALIGN);
295 *dst = (typeof(*dst)) {
296 /* Add one for the terminating zero byte. */
297 .iov_base = para_malloc(l2 + 1),
300 RC4(key, l1, src->iov_base, dst->iov_base);
302 unsigned char remainder[RC4_ALIGN] = "";
303 memcpy(remainder, src->iov_base + l1, len - l1);
304 RC4(key, len - l1, remainder, dst->iov_base + l1);
306 ((char *)dst->iov_base)[len] = '\0';
309 void hash_function(const char *data, unsigned long len, unsigned char *hash)
313 SHA1_Update(&c, data, len);
314 SHA1_Final(hash, &c);