2 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file crypt.c openssl-based RSA 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>
23 * Fill a buffer with random content.
25 * \param buf The buffer to fill.
26 * \param num The size of \a buf in bytes.
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().
33 void get_random_bytes_or_die(unsigned char *buf, int num)
37 /* RAND_bytes() returns 1 on success, 0 otherwise. */
38 if (RAND_bytes(buf, num) == 1)
40 err = ERR_get_error();
41 PARA_EMERG_LOG("%s\n", ERR_reason_error_string(err));
46 * Seed pseudo random number generators.
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().
53 * \sa RAND_load_file(3), \ref get_random_bytes_or_die(), srandom(3),
54 * random(3), \ref para_random().
56 void init_random_seed_or_die(void)
58 int seed, ret = RAND_load_file("/dev/urandom", 64);
61 PARA_EMERG_LOG("could not seed PRNG (ret = %d)\n", ret);
64 get_random_bytes_or_die((unsigned char *)&seed, sizeof(seed));
68 static int check_key_file(const char *file, int private)
72 if (stat(file, &st) != 0)
73 return -ERRNO_TO_PARA_ERROR(errno);
74 if (private != LOAD_PRIVATE_KEY)
76 if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0)
81 static EVP_PKEY *load_key(const char *file, int private)
84 EVP_PKEY *pkey = NULL;
85 int ret = check_key_file(file, private);
88 PARA_ERROR_LOG("%s\n", para_strerror(-ret));
91 key = BIO_new(BIO_s_file());
94 if (BIO_read_filename(key, file) > 0) {
95 if (private == LOAD_PRIVATE_KEY)
96 pkey = PEM_read_bio_PrivateKey(key, NULL, NULL, NULL);
98 pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);
105 * read an RSA key from a file
107 * \param key_file the file containing the key
108 * \param rsa RSA structure is returned here
109 * \param private if non-zero, read the private key, otherwise the public key
111 * \return The size of the RSA key on success, negative on errors.
113 * \sa openssl(1), rsa(1).
115 int get_rsa_key(char *key_file, RSA **rsa, int private)
117 EVP_PKEY *key = load_key(key_file, private);
120 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
122 *rsa = EVP_PKEY_get1_RSA(key);
126 return RSA_size(*rsa);
130 * free an RSA structure
132 * \param rsa pointer to the RSA struct to free
134 * This must be called for any key obtained by get_rsa_key().
136 void rsa_free(RSA *rsa)
143 * decrypt a buffer using an RSA key
145 * \param key_file full path of the rsa key
146 * \param outbuf the output buffer
147 * \param inbuf the encrypted input buffer
148 * \param rsa_inlen the length of \a inbuf
150 * The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
152 * \return The size of the recovered plaintext on success, negative on errors.
154 * \sa RSA_private_decrypt(3)
156 int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
160 int ret, inlen = rsa_inlen;
164 ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
168 * RSA is vulnerable to timing attacks. Generate a random blinding
169 * factor to protect against this kind of attack.
172 if (RSA_blinding_on(rsa, NULL) == 0)
174 ret = RSA_private_decrypt(inlen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
175 RSA_blinding_off(rsa);
184 * encrypt a buffer using an RSA key
186 * \param rsa: public rsa key
187 * \param inbuf the input buffer
188 * \param len the length of \a inbuf
189 * \param outbuf the output buffer
191 * \return The size of the encrypted data on success, negative on errors
193 * \sa RSA_public_encrypt(3)
195 int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
196 unsigned len, unsigned char *outbuf)
198 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
202 ret = RSA_public_encrypt(flen, inbuf, outbuf, rsa, RSA_PKCS1_OAEP_PADDING);
203 return ret < 0? -E_ENCRYPT : ret;
207 * Encrypt and send a buffer.
209 * \param rc4c The rc4 crypt context.
210 * \param buf The buffer to send.
211 * \param len The size of \a buf in bytes.
213 * \return The return value of the underyling call to write_all().
215 * \sa \ref write_all(), RC4(3).
217 int rc4_send_bin_buffer(struct rc4_context *rc4c, const char *buf, size_t len)
223 tmp = para_malloc(len);
224 RC4(&rc4c->send_key, len, (const unsigned char *)buf, tmp);
225 ret = write_all(rc4c->fd, (char *)tmp, &len);
231 * Encrypt and send a \p NULL-terminated buffer.
233 * \param rc4c The rc4 crypt context.
234 * \param buf The buffer to send.
236 * \return The return value of the underyling call to rc4_send_bin_buffer().
238 int rc4_send_buffer(struct rc4_context *rc4c, const char *buf)
240 return rc4_send_bin_buffer(rc4c, buf, strlen(buf));
244 * Format, encrypt and send a buffer.
246 * \param rc4c The rc4 crypt context.
247 * \param fmt A format string.
249 * \return The return value of the underyling call to rc4_send_buffer().
251 __printf_2_3 int rc4_send_va_buffer(struct rc4_context *rc4c, const char *fmt, ...)
256 PARA_VSPRINTF(fmt, msg);
257 ret = rc4_send_buffer(rc4c, msg);
263 * Receive a buffer and decrypt it.
265 * \param rc4c The rc4 crypt context.
266 * \param buf The buffer to write the decrypted data to.
267 * \param size The size of \a buf.
269 * \return The number of bytes received on success, negative on errors, zero if
270 * the peer has performed an orderly shutdown.
272 * \sa recv(2), RC4(3).
274 int rc4_recv_bin_buffer(struct rc4_context *rc4c, char *buf, size_t size)
276 unsigned char *tmp = para_malloc(size);
277 ssize_t ret = recv(rc4c->fd, tmp, size, 0);
280 RC4(&rc4c->recv_key, ret, tmp, (unsigned char *)buf);
282 ret = -ERRNO_TO_PARA_ERROR(errno);
288 * Receive a buffer, decrypt it and write terminating NULL byte.
290 * \param rc4c The rc4 crypt context.
291 * \param buf The buffer to write the decrypted data to.
292 * \param size The size of \a buf.
294 * Read at most \a size - 1 bytes from file descriptor given by \a rc4c,
295 * decrypt the received data and write a NULL byte at the end of the decrypted
298 * \return The return value of the underlying call to \ref
299 * rc4_recv_bin_buffer().
301 int rc4_recv_buffer(struct rc4_context *rc4c, char *buf, size_t size)
306 n = rc4_recv_bin_buffer(rc4c, buf, size - 1);