com_ff(): Depreciate "n-" syntax.
[paraslash.git] / openssl.c
1 /* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
2
3 /** \file openssl.c Openssl-based encryption/decryption routines. */
4
5 #include <regex.h>
6 #include <sys/types.h>
7 #include <sys/socket.h>
8 #include <openssl/rand.h>
9 #include <openssl/err.h>
10 #include <openssl/pem.h>
11 #include <openssl/sha.h>
12 #include <openssl/bn.h>
13 #include <openssl/aes.h>
14
15 #include "para.h"
16 #include "error.h"
17 #include "string.h"
18 #include "crypt.h"
19 #include "crypt_backend.h"
20 #include "portable_io.h"
21
22 struct asymmetric_key {
23 RSA *rsa;
24 };
25
26 void get_random_bytes_or_die(unsigned char *buf, int num)
27 {
28 unsigned long err;
29
30 /* RAND_bytes() returns 1 on success, 0 otherwise. */
31 if (RAND_bytes(buf, num) == 1)
32 return;
33 err = ERR_get_error();
34 PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
35 exit(EXIT_FAILURE);
36 }
37
38 /*
39 * Read 64 bytes from /dev/urandom and add them to the SSL PRNG. Seed the PRNG
40 * used by random(3) with a random seed obtained from SSL. If /dev/urandom is
41 * not readable, the function calls exit().
42 *
43 * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
44 * random(3), \ref para_random().
45 */
46 void crypt_init(void)
47 {
48 int seed, ret = RAND_load_file("/dev/urandom", 64);
49
50 if (ret != 64) {
51 PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
52 exit(EXIT_FAILURE);
53 }
54 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
55 srandom(seed);
56 }
57
58 void crypt_shutdown(void)
59 {
60 CRYPTO_cleanup_all_ex_data();
61 }
62
63 static int get_private_key(const char *path, RSA **rsa)
64 {
65 EVP_PKEY *pkey;
66 BIO *bio = BIO_new(BIO_s_file());
67
68 *rsa = NULL;
69 if (!bio)
70 return -E_PRIVATE_KEY;
71 if (BIO_read_filename(bio, path) <= 0)
72 goto bio_free;
73 pkey = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
74 if (!pkey)
75 goto bio_free;
76 *rsa = EVP_PKEY_get1_RSA(pkey);
77 EVP_PKEY_free(pkey);
78 bio_free:
79 BIO_free(bio);
80 return *rsa? RSA_size(*rsa) : -E_PRIVATE_KEY;
81 }
82
83 /*
84 * The public key loading functions below were inspired by corresponding code
85 * of openssh-5.2p1, Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo,
86 * Finland. However, not much of the original code remains.
87 */
88
89 static int read_bignum(const unsigned char *buf, size_t len, BIGNUM **result)
90 {
91 const unsigned char *p = buf, *end = buf + len;
92 uint32_t bnsize;
93 BIGNUM *bn;
94
95 if (p + 4 < p)
96 return -E_BIGNUM;
97 if (p + 4 > end)
98 return -E_BIGNUM;
99 bnsize = read_u32_be(p);
100 PARA_DEBUG_LOG("bnsize: %u\n", bnsize);
101 p += 4;
102 if (p + bnsize < p)
103 return -E_BIGNUM;
104 if (p + bnsize > end)
105 return -E_BIGNUM;
106 if (bnsize > 8192)
107 return -E_BIGNUM;
108 bn = BN_bin2bn(p, bnsize, NULL);
109 if (!bn)
110 return -E_BIGNUM;
111 *result = bn;
112 return bnsize + 4;
113 }
114
115 static int read_rsa_bignums(const unsigned char *blob, int blen, RSA **result)
116 {
117 int ret;
118 RSA *rsa;
119 BIGNUM *n, *e;
120 const unsigned char *p = blob, *end = blob + blen;
121
122 rsa = RSA_new();
123 if (!rsa)
124 return -E_BIGNUM;
125 ret = read_bignum(p, end - p, &e);
126 if (ret < 0)
127 goto fail;
128 p += ret;
129 ret = read_bignum(p, end - p, &n);
130 if (ret < 0)
131 goto fail;
132 #ifdef HAVE_RSA_SET0_KEY
133 RSA_set0_key(rsa, n, e, NULL);
134 #else
135 rsa->n = n;
136 rsa->e = e;
137 #endif
138 *result = rsa;
139 return 1;
140 fail:
141 RSA_free(rsa);
142 return ret;
143 }
144
145 int apc_get_pubkey(const char *key_file, struct asymmetric_key **result)
146 {
147 unsigned char *blob;
148 size_t decoded_size;
149 int ret;
150 struct asymmetric_key *key = para_malloc(sizeof(*key));
151
152 ret = decode_ssh_key(key_file, &blob, &decoded_size);
153 if (ret < 0)
154 goto out;
155 ret = read_rsa_bignums(blob + ret, decoded_size - ret, &key->rsa);
156 if (ret < 0)
157 goto free_blob;
158 ret = RSA_size(key->rsa);
159 assert(ret > 0);
160 *result = key;
161 free_blob:
162 free(blob);
163 out:
164 if (ret < 0) {
165 free(key);
166 *result = NULL;
167 PARA_ERROR_LOG("can not load key %s\n", key_file);
168 }
169 return ret;
170 }
171
172 void apc_free_pubkey(struct asymmetric_key *key)
173 {
174 if (!key)
175 return;
176 RSA_free(key->rsa);
177 free(key);
178 }
179
180 int apc_priv_decrypt(const char *key_file, unsigned char *outbuf,
181 unsigned char *inbuf, int inlen)
182 {
183 struct asymmetric_key *priv;
184 int ret;
185
186 ret = check_private_key_file(key_file);
187 if (ret < 0)
188 return ret;
189 if (inlen < 0)
190 return -E_RSA;
191 priv = para_malloc(sizeof(*priv));
192 ret = get_private_key(key_file, &priv->rsa);
193 if (ret < 0) {
194 free(priv);
195 return ret;
196 }
197 /*
198 * RSA is vulnerable to timing attacks. Generate a random blinding
199 * factor to protect against this kind of attack.
200 */
201 ret = -E_BLINDING;
202 if (RSA_blinding_on(priv->rsa, NULL) == 0)
203 goto out;
204 ret = RSA_private_decrypt(inlen, inbuf, outbuf, priv->rsa,
205 RSA_PKCS1_OAEP_PADDING);
206 RSA_blinding_off(priv->rsa);
207 if (ret <= 0)
208 ret = -E_DECRYPT;
209 out:
210 RSA_free(priv->rsa);
211 free(priv);
212 return ret;
213 }
214
215 int apc_pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
216 unsigned len, unsigned char *outbuf)
217 {
218 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
219
220 if (flen < 0)
221 return -E_ENCRYPT;
222 ret = RSA_public_encrypt(flen, inbuf, outbuf, pub->rsa,
223 RSA_PKCS1_OAEP_PADDING);
224 return ret < 0? -E_ENCRYPT : ret;
225 }
226
227 struct stream_cipher {
228 EVP_CIPHER_CTX *aes;
229 };
230
231 struct stream_cipher *sc_new(const unsigned char *data, int len)
232 {
233 struct stream_cipher *sc = para_malloc(sizeof(*sc));
234
235 assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
236 sc->aes = EVP_CIPHER_CTX_new();
237 EVP_EncryptInit_ex(sc->aes, EVP_aes_128_ctr(), NULL, data,
238 data + AES_CRT128_BLOCK_SIZE);
239 return sc;
240 }
241
242 void sc_free(struct stream_cipher *sc)
243 {
244 if (!sc)
245 return;
246 EVP_CIPHER_CTX_free(sc->aes);
247 free(sc);
248 }
249
250 static void aes_ctr128_crypt(EVP_CIPHER_CTX *ctx, struct iovec *src,
251 struct iovec *dst)
252 {
253 int ret, inlen = src->iov_len, outlen, tmplen;
254
255 *dst = (typeof(*dst)) {
256 /* Add one for the terminating zero byte. */
257 .iov_base = para_malloc(inlen + 1),
258 .iov_len = inlen
259 };
260 ret = EVP_EncryptUpdate(ctx, dst->iov_base, &outlen, src->iov_base, inlen);
261 assert(ret != 0);
262 ret = EVP_EncryptFinal_ex(ctx, dst->iov_base + outlen, &tmplen);
263 assert(ret != 0);
264 outlen += tmplen;
265 ((char *)dst->iov_base)[outlen] = '\0';
266 dst->iov_len = outlen;
267 }
268
269 void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
270 {
271 return aes_ctr128_crypt(sc->aes, src, dst);
272 }
273
274 void hash_function(const char *data, unsigned long len, unsigned char *hash)
275 {
276 SHA_CTX c;
277 SHA1_Init(&c);
278 SHA1_Update(&c, data, len);
279 SHA1_Final(hash, &c);
280 }