2 * Copyright (C) 2005-2012 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
);
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 stream_cipher
{
267 struct stream_cipher
*sc_new(const unsigned char *data
, int len
)
269 struct stream_cipher
*sc
= para_malloc(sizeof(*sc
));
270 RC4_set_key(&sc
->key
, len
, data
);
274 void sc_free(struct stream_cipher
*sc
)
280 * The RC4() implementation of openssl apparently reads and writes data in
281 * blocks of 8 bytes. So we have to make sure our buffer sizes are a multiple
286 int sc_send_bin_buffer(struct stream_cipher_context
*scc
, char *buf
,
291 static unsigned char remainder
[RC4_ALIGN
];
292 size_t l1
= ROUND_DOWN(len
, RC4_ALIGN
), l2
= ROUND_UP(len
, RC4_ALIGN
);
295 tmp
= para_malloc(l2
);
296 RC4(&scc
->send
->key
, l1
, (const unsigned char *)buf
, tmp
);
298 memcpy(remainder
, buf
+ l1
, len
- l1
);
299 RC4(&scc
->send
->key
, len
- l1
, remainder
, tmp
+ l1
);
301 ret
= write_all(scc
->fd
, (char *)tmp
, &len
);
306 int sc_recv_bin_buffer(struct stream_cipher_context
*scc
, char *buf
,
309 unsigned char *tmp
= para_malloc(ROUND_UP(size
, RC4_ALIGN
));
310 ssize_t ret
= recv(scc
->fd
, tmp
, size
, 0);
313 RC4(&scc
->recv
->key
, ret
, tmp
, (unsigned char *)buf
);
315 ret
= -ERRNO_TO_PARA_ERROR(errno
);
320 void hash_function(const char *data
, unsigned long len
, unsigned char *hash
)
324 SHA1_Update(&c
, data
, len
);
325 SHA1_Final(hash
, &c
);