net.c: make it compile without ucred
[paraslash.git] / crypt.c
1 /*
2 * Copyright (C) 2005-2006 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18
19 /** \file crypt.c openssl-based RSA encryption/decryption routines */
20
21 #include <openssl/pem.h>
22 #include "para.h"
23 #include "error.h"
24 #include "string.h"
25
26 /** \cond used to distinguish between loading of private/public key */
27 #define LOAD_PUBLIC_KEY 0
28 #define LOAD_PRIVATE_KEY 1
29 /** \endcond **/
30
31 static EVP_PKEY *load_key(const char *file, int private)
32 {
33 BIO *key;
34 EVP_PKEY *pkey = NULL;
35
36 key = BIO_new(BIO_s_file());
37 if (!key)
38 return NULL;
39 if (BIO_read_filename(key, file) > 0) {
40 if (private == LOAD_PRIVATE_KEY)
41 pkey = PEM_read_bio_PrivateKey(key, NULL, NULL, NULL);
42 else
43 pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);
44 }
45 BIO_free(key);
46 return pkey;
47 }
48
49 static int get_key(char *key_file, RSA **rsa, int private)
50 {
51 EVP_PKEY *key = load_key(key_file, private);
52
53 if (!key)
54 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY : -E_PUBLIC_KEY;
55 *rsa = EVP_PKEY_get1_RSA(key);
56 EVP_PKEY_free(key);
57 if (!*rsa)
58 return -E_RSA;
59 return RSA_size(*rsa);
60 }
61
62 /**
63 * decrypt a buffer using an RSA key
64 *
65 * \param key_file full path of the rsa key
66 * \param outbuf the output buffer
67 * \param inbuf the encrypted input buffer
68 * \param rsa_inlen the length of \a inbuf
69 *
70 * The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
71 *
72 * \return The size of the recovered plaintext on success, negative on errors.
73 *
74 * \sa RSA_private_decrypt(3)
75 **/
76 int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
77 int rsa_inlen)
78 {
79 RSA *rsa;
80 int ret = get_key(key_file, &rsa, LOAD_PRIVATE_KEY);
81
82 if (ret < 0)
83 return ret;
84 ret = RSA_private_decrypt(rsa_inlen, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
85 return (ret > 0)? ret : -E_DECRYPT;
86 }
87
88 /**
89 * decrypt the challenge number sent by para_server
90 *
91 * \param key_file full path of the rsa key
92 * \param challenge_nr result is stored here
93 * \param inbuf the input buffer
94 * \param rsa_inlen the length of \a inbuf
95 *
96 * \return positive on success, negative on errors
97 *
98 * \sa para_decrypt_buffer()
99 */
100 int para_decrypt_challenge(char *key_file, long unsigned *challenge_nr,
101 unsigned char *inbuf, int rsa_inlen)
102 {
103 unsigned char *rsa_out = OPENSSL_malloc(128);
104 int ret = para_decrypt_buffer(key_file, rsa_out, inbuf, rsa_inlen);
105
106 if (ret >= 0)
107 ret = sscanf((char *)rsa_out, "%lu", challenge_nr) == 1?
108 1 : -E_CHALLENGE;
109 OPENSSL_free(rsa_out);
110 return ret;
111 }
112
113 /**
114 * encrypt a buffer using an RSA key
115 *
116 * \param key_file full path of the rsa key
117 * \param inbuf the input buffer
118 * \param len the length of \a inbuf
119 * \param outbuf the output buffer
120 *
121 * \return The size of the encrypted data on success, negative on errors
122 *
123 * \sa RSA_public_encrypt(3)
124 */
125 int para_encrypt_buffer(char *key_file, unsigned char *inbuf,
126 const unsigned len, unsigned char *outbuf)
127 {
128 RSA *rsa;
129 int ret = get_key(key_file, &rsa, LOAD_PUBLIC_KEY);
130
131 if (ret < 0)
132 return ret;
133 ret = RSA_public_encrypt(len, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
134 return ret < 0? -E_ENCRYPT : ret;
135 }
136
137 /**
138 * encrypt the given challenge number
139 *
140 * \param key_file full path of the rsa key
141 * \param challenge_nr the number to be encrypted
142 * \param outbuf the output buffer
143 *
144 * \a outbuf must be at least 64 bytes long
145 *
146 * \return The size of the encrypted data on success, negative on errors
147 *
148 * \sa para_encrypt_buffer()
149 *
150 */
151 int para_encrypt_challenge(char *key_file, long unsigned challenge_nr,
152 unsigned char *outbuf)
153 {
154 unsigned char *inbuf = (unsigned char*) make_message("%lu", challenge_nr);
155 int ret = para_encrypt_buffer(key_file, inbuf, strlen((char *)inbuf), outbuf);
156 free(inbuf);
157 return ret;
158 }
159