NEWS update
[paraslash.git] / crypt.c
1 /*
2 * Copyright (C) 2005-2007 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 "para.h"
22 #include "error.h"
23 #include "string.h"
24 #include "crypt.h"
25
26 static EVP_PKEY *load_key(const char *file, int private)
27 {
28 BIO *key;
29 EVP_PKEY *pkey = NULL;
30
31 key = BIO_new(BIO_s_file());
32 if (!key)
33 return NULL;
34 if (BIO_read_filename(key, file) > 0) {
35 if (private == LOAD_PRIVATE_KEY)
36 pkey = PEM_read_bio_PrivateKey(key, NULL, NULL, NULL);
37 else
38 pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);
39 }
40 BIO_free(key);
41 return pkey;
42 }
43
44 /**
45 * read an RSA key from a file
46 *
47 * \param key_file the file containing the key
48 * \param rsa RSA structure is returned here
49 * \param private if non-zero, read the private key, otherwise the public key
50 *
51 * \return The size of the RSA key on success, negative on errors.
52 *
53 * \sa openssl(1), rsa(1).
54 */
55 int get_rsa_key(char *key_file, RSA **rsa, int private)
56 {
57 EVP_PKEY *key = load_key(key_file, private);
58
59 if (!key)
60 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY
61 : -E_PUBLIC_KEY;
62 *rsa = EVP_PKEY_get1_RSA(key);
63 EVP_PKEY_free(key);
64 if (!*rsa)
65 return -E_RSA;
66 return RSA_size(*rsa);
67 }
68
69 /**
70 * free an RSA structure
71 *
72 * \param rsa pointer to the RSA struct to free
73 *
74 * This must be called for any key obtained by get_rsa_key().
75 */
76 void rsa_free(RSA *rsa)
77 {
78 if (rsa)
79 RSA_free(rsa);
80 }
81
82 /**
83 * decrypt a buffer using an RSA key
84 *
85 * \param key_file full path of the rsa key
86 * \param outbuf the output buffer
87 * \param inbuf the encrypted input buffer
88 * \param rsa_inlen the length of \a inbuf
89 *
90 * The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
91 *
92 * \return The size of the recovered plaintext on success, negative on errors.
93 *
94 * \sa RSA_private_decrypt(3)
95 **/
96 int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
97 unsigned rsa_inlen)
98 {
99 RSA *rsa;
100 int ret, inlen = rsa_inlen;
101
102 if (inlen < 0)
103 return -E_RSA;
104 ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
105 if (ret < 0)
106 return ret;
107 ret = RSA_private_decrypt(inlen, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
108 rsa_free(rsa);
109 return (ret > 0)? ret : -E_DECRYPT;
110 }
111
112 /**
113 * decrypt the challenge number sent by para_server
114 *
115 * \param key_file full path of the rsa key
116 * \param challenge_nr result is stored here
117 * \param inbuf the input buffer
118 * \param rsa_inlen the length of \a inbuf
119 *
120 * \return positive on success, negative on errors
121 *
122 * \sa para_decrypt_buffer()
123 */
124 int para_decrypt_challenge(char *key_file, long unsigned *challenge_nr,
125 unsigned char *inbuf, unsigned rsa_inlen)
126 {
127 unsigned char *rsa_out = OPENSSL_malloc(rsa_inlen + 1);
128 int ret = para_decrypt_buffer(key_file, rsa_out, inbuf, rsa_inlen);
129
130 if (ret >= 0) {
131 rsa_out[ret] = '\0';
132 ret = sscanf((char *)rsa_out, "%lu", challenge_nr) == 1?
133 1 : -E_CHALLENGE;
134 }
135 OPENSSL_free(rsa_out);
136 return ret;
137 }
138
139 /**
140 * encrypt a buffer using an RSA key
141 *
142 * \param rsa: public rsa key
143 * \param inbuf the input buffer
144 * \param len the length of \a inbuf
145 * \param outbuf the output buffer
146 *
147 * \return The size of the encrypted data on success, negative on errors
148 *
149 * \sa RSA_public_encrypt(3)
150 */
151 int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
152 unsigned len, unsigned char *outbuf)
153 {
154 int ret, flen = len; /* RSA_public_encrypt expects a signed int */
155
156 if (flen < 0)
157 return -E_ENCRYPT;
158 ret = RSA_public_encrypt(flen, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
159 return ret < 0? -E_ENCRYPT : ret;
160 }
161
162 /**
163 * encrypt the given challenge number
164 *
165 * \param rsa: public rsa key
166 * \param challenge_nr the number to be encrypted
167 * \param outbuf the output buffer
168 *
169 * \a outbuf must be at least 64 bytes long
170 *
171 * \return The size of the encrypted data on success, negative on errors
172 *
173 * \sa para_encrypt_buffer()
174 *
175 */
176 int para_encrypt_challenge(RSA* rsa, long unsigned challenge_nr,
177 unsigned char *outbuf)
178 {
179 unsigned char *inbuf = (unsigned char*) make_message("%lu", challenge_nr);
180 int ret = para_encrypt_buffer(rsa, inbuf, strlen((char *)inbuf), outbuf);
181 free(inbuf);
182 return ret;
183 }
184