2 * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
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>
18 #include <openssl/aes.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);
155 int get_asymmetric_key(const char *key_file, int private,
156 struct asymmetric_key **result)
158 struct asymmetric_key *key = NULL;
160 unsigned char *blob = NULL;
161 size_t map_size, blob_size, decoded_size;
165 key = para_malloc(sizeof(*key));
167 ret = get_openssl_key(key_file, &key->rsa, LOAD_PRIVATE_KEY);
170 ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
173 ret = is_ssh_rsa_key(map, map_size);
175 ret = para_munmap(map, map_size);
179 ret = get_openssl_key(key_file, &key->rsa, LOAD_PUBLIC_KEY);
183 PARA_INFO_LOG("decoding public rsa-ssh key %s\n", key_file);
184 ret = -ERRNO_TO_PARA_ERROR(EOVERFLOW);
185 if (map_size > INT_MAX / 4)
187 blob_size = 2 * map_size;
188 blob = para_malloc(blob_size);
189 ret = uudecode(cp, blob, blob_size);
193 ret = check_ssh_key_header(blob, decoded_size);
196 ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
199 ret = RSA_size(key->rsa);
201 ret2 = para_munmap(map, map_size);
202 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 aes_ctr_128_context {
265 unsigned char ivec[AES_CRT128_BLOCK_SIZE];
266 unsigned char ecount[AES_CRT128_BLOCK_SIZE];
270 struct stream_cipher {
274 struct aes_ctr_128_context aes;
278 struct stream_cipher *sc_new(const unsigned char *data, int len,
282 struct stream_cipher *sc = para_malloc(sizeof(*sc));
283 struct aes_ctr_128_context *aes;
285 sc->use_aes = use_aes;
287 RC4_set_key(&sc->context.rc4_key, len, data);
290 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
291 aes = &sc->context.aes;
292 ret = AES_set_encrypt_key(data, AES_CRT128_BLOCK_SIZE * 8 /* bits */,
295 memcpy(aes->ivec, data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
300 void sc_free(struct stream_cipher *sc)
306 * The RC4() implementation of openssl apparently reads and writes data in
307 * blocks of 8 bytes. So we have to make sure our buffer sizes are a multiple
312 static void rc4_crypt(RC4_KEY *key, struct iovec *src, struct iovec *dst)
314 size_t len = src->iov_len, l1, l2;
317 assert(len < ((typeof(src->iov_len))-1) / 2);
318 l1 = ROUND_DOWN(len, RC4_ALIGN);
319 l2 = ROUND_UP(len, RC4_ALIGN);
321 *dst = (typeof(*dst)) {
322 /* Add one for the terminating zero byte. */
323 .iov_base = para_malloc(l2 + 1),
326 RC4(key, l1, src->iov_base, dst->iov_base);
328 unsigned char remainder[RC4_ALIGN] = "";
329 memcpy(remainder, src->iov_base + l1, len - l1);
330 RC4(key, len - l1, remainder, dst->iov_base + l1);
332 ((char *)dst->iov_base)[len] = '\0';
335 static void aes_ctr128_crypt(struct aes_ctr_128_context *aes, struct iovec *src,
338 size_t len = src->iov_len;
340 *dst = (typeof(*dst)) {
341 /* Add one for the terminating zero byte. */
342 .iov_base = para_malloc(len + 1),
345 AES_ctr128_encrypt(src->iov_base, dst->iov_base, len,
346 &aes->key, aes->ivec, aes->ecount, &aes->num);
347 ((char *)dst->iov_base)[len] = '\0';
350 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
353 return aes_ctr128_crypt(&sc->context.aes, src, dst);
354 return rc4_crypt(&sc->context.rc4_key, src, dst);
357 void hash_function(const char *data, unsigned long len, unsigned char *hash)
361 SHA1_Update(&c, data, len);
362 SHA1_Final(hash, &c);