Add mood methods {artist, title, album, comment}_matches.
[paraslash.git] / crypt.c
1 /*
2 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file crypt.c openssl-based RSA encryption/decryption routines */
8
9 #include <regex.h>
10 #include <dirent.h>
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
17 #include "para.h"
18 #include "error.h"
19 #include "string.h"
20 #include "crypt.h"
21 #include "fd.h"
22 /**
23 * Fill a buffer with random content.
24 *
25 * \param buf The buffer to fill.
26 * \param num The size of \a buf in bytes.
27 *
28 * This function puts \a num cryptographically strong pseudo-random bytes into
29 * buf. If libssl can not guarantee an unpredictable byte sequence (for example
30 * because the PRNG has not been seeded with enough randomness) the function
31 * logs an error message and calls exit().
32 */
33 void get_random_bytes_or_die(unsigned char *buf, int num)
34 {
35 unsigned long err;
36
37 /* RAND_bytes() returns 1 on success, 0 otherwise. */
38 if (RAND_bytes(buf, num) == 1)
39 return;
40 err = ERR_get_error();
41 PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
42 exit(EXIT_FAILURE);
43 }
44
45 /**
46 * Seed pseudo random number generators.
47 *
48 * This function reads 64 bytes from /dev/urandom and adds them to the SSL
49 * PRNG. It also seeds the PRNG used by random() with a random seed obtained
50 * from SSL. If /dev/random could not be read, an error message is logged and
51 * the function calls exit().
52 *
53 * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
54 * random(3), \ref para_random().
55 */
56 void init_random_seed_or_die(void)
57 {
58 int seed, ret = RAND_load_file("/dev/urandom", 64);
59
60 if (ret != 64) {
61 PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
62 exit(EXIT_FAILURE);
63 }
64 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
65 srandom(seed);
66 }
67
68 static EVP_PKEY *load_key(const char *file, int private)
69 {
70 BIO *key;
71 EVP_PKEY *pkey = NULL;
72
73 key = BIO_new(BIO_s_file());
74 if (!key)
75 return NULL;
76 if (BIO_read_filename(key, file) > 0) {
77 if (private == LOAD_PRIVATE_KEY)
78 pkey = PEM_read_bio_PrivateKey(key, NULL, NULL, NULL);
79 else
80 pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);
81 }
82 BIO_free(key);
83 return pkey;
84 }
85
86 /**
87 * read an RSA key from a file
88 *
89 * \param key_file the file containing the key
90 * \param rsa RSA structure is returned here
91 * \param private if non-zero, read the private key, otherwise the public key
92 *
93 * \return The size of the RSA key on success, negative on errors.
94 *
95 * \sa openssl(1), rsa(1).
96 */
97 int get_rsa_key(char *key_file, RSA **rsa, int private)
98 {
99 EVP_PKEY *key = load_key(key_file, private);
100
101 if (!key)
102 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
103 : -E_PUBLIC_KEY;
104 *rsa = EVP_PKEY_get1_RSA(key);
105 EVP_PKEY_free(key);
106 if (!*rsa)
107 return -E_RSA;
108 return RSA_size(*rsa);
109 }
110
111 /**
112 * free an RSA structure
113 *
114 * \param rsa pointer to the RSA struct to free
115 *
116 * This must be called for any key obtained by get_rsa_key().
117 */
118 void rsa_free(RSA *rsa)
119 {
120 if (rsa)
121 RSA_free(rsa);
122 }
123
124 /**
125 * decrypt a buffer using an RSA key
126 *
127 * \param key_file full path of the rsa key
128 * \param outbuf the output buffer
129 * \param inbuf the encrypted input buffer
130 * \param rsa_inlen the length of \a inbuf
131 *
132 * The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
133 *
134 * \return The size of the recovered plaintext on success, negative on errors.
135 *
136 * \sa RSA_private_decrypt(3)
137 **/
138 int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
139 unsigned rsa_inlen)
140 {
141 RSA *rsa;
142 int ret, inlen = rsa_inlen;
143
144 if (inlen < 0)
145 return -E_RSA;
146 ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
147 if (ret < 0)
148 return ret;
149 ret = RSA_private_decrypt(inlen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
150 rsa_free(rsa);
151 return (ret > 0)? ret : -E_DECRYPT;
152 }
153
154 /**
155 * encrypt a buffer using an RSA key
156 *
157 * \param rsa: public rsa key
158 * \param inbuf the input buffer
159 * \param len the length of \a inbuf
160 * \param outbuf the output buffer
161 *
162 * \return The size of the encrypted data on success, negative on errors
163 *
164 * \sa RSA_public_encrypt(3)
165 */
166 int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
167 unsigned len, unsigned char *outbuf)
168 {
169 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
170
171 if (flen < 0)
172 return -E_ENCRYPT;
173 ret = RSA_public_encrypt(flen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
174 return ret < 0? -E_ENCRYPT : ret;
175 }
176
177 /**
178 * Encrypt and send a buffer.
179 *
180 * \param rc4c The rc4 crypt context.
181 * \param buf The buffer to send.
182 * \param len The size of \a buf in bytes.
183 *
184 * \return The return value of the underyling call to write_all().
185 *
186 * \sa \ref write_all(), RC4(3).
187 */
188 int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len)
189 {
190 int ret;
191 unsigned char *tmp;
192
193 assert(len);
194 tmp = para_malloc(len);
195 RC4(&rc4c->send_key, len, (const unsigned char *)buf, tmp);
196 ret = write_all(rc4c->fd, (char *)tmp, &len);
197 free(tmp);
198 return ret;
199 }
200
201 /**
202 * Encrypt and send a \p NULL-terminated buffer.
203 *
204 * \param rc4c The rc4 crypt context.
205 * \param buf The buffer to send.
206 *
207 * \return The return value of the underyling call to rc4_send_bin_buffer().
208 */
209 int rc4_send_buffer(struct rc4_context *rc4c, const char *buf)
210 {
211 return rc4_send_bin_buffer(rc4c, buf, strlen(buf));
212 }
213
214 /**
215 * Format, encrypt and send a buffer.
216 *
217 * \param rc4c The rc4 crypt context.
218 * \param fmt A format string.
219 *
220 * \return The return value of the underyling call to rc4_send_buffer().
221 */
222 __printf_2_3 int rc4_send_va_buffer(struct rc4_context *rc4c, const char *fmt, ...)
223 {
224 char *msg;
225 int ret;
226
227 PARA_VSPRINTF(fmt, msg);
228 ret = rc4_send_buffer(rc4c, msg);
229 free(msg);
230 return ret;
231 }
232
233 /**
234 * Receive a buffer and decrypt it.
235 *
236 * \param rc4c The rc4 crypt context.
237 * \param buf The buffer to write the decrypted data to.
238 * \param size The size of \a buf.
239 *
240 * \return The number of bytes received on success, negative on errors, zero if
241 * the peer has performed an orderly shutdown.
242 *
243 * \sa recv(2), RC4(3).
244 */
245 int rc4_recv_bin_buffer(struct rc4_context *rc4c, char *buf, size_t size)
246 {
247 unsigned char *tmp = para_malloc(size);
248 ssize_t ret = recv(rc4c->fd, tmp, size, 0);
249
250 if (ret > 0)
251 RC4(&rc4c->recv_key, ret, tmp, (unsigned char *)buf);
252 else if (ret < 0)
253 ret = -ERRNO_TO_PARA_ERROR(errno);
254 free(tmp);
255 return ret;
256 }
257
258 /**
259 * Receive a buffer, decrypt it and write terminating NULL byte.
260 *
261 * \param rc4c The rc4 crypt context.
262 * \param buf The buffer to write the decrypted data to.
263 * \param size The size of \a buf.
264 *
265 * Read at most \a size - 1 bytes from file descriptor given by \a rc4c,
266 * decrypt the received data and write a NULL byte at the end of the decrypted
267 * data.
268 *
269 * \return The return value of the underlying call to \ref
270 * rc4_recv_bin_buffer().
271 */
272 int rc4_recv_buffer(struct rc4_context *rc4c, char *buf, size_t size)
273 {
274 int n;
275
276 assert(size);
277 n = rc4_recv_bin_buffer(rc4c, buf, size - 1);
278 if (n >= 0)
279 buf[n] = '\0';
280 else
281 *buf = '\0';
282 return n;
283 }