move LOAD_PUBLIC_KEY and LOAD_PRIVATE_KEY to crypt.h
[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 "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 int get_rsa_key(char *key_file, RSA **rsa, int private)
46 {
47 EVP_PKEY *key = load_key(key_file, private);
48
49 if (!key)
50 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY : -E_PUBLIC_KEY;
51 *rsa = EVP_PKEY_get1_RSA(key);
52 EVP_PKEY_free(key);
53 if (!*rsa)
54 return -E_RSA;
55 return RSA_size(*rsa);
56 }
57
58 /**
59 * decrypt a buffer using an RSA key
60 *
61 * \param key_file full path of the rsa key
62 * \param outbuf the output buffer
63 * \param inbuf the encrypted input buffer
64 * \param rsa_inlen the length of \a inbuf
65 *
66 * The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
67 *
68 * \return The size of the recovered plaintext on success, negative on errors.
69 *
70 * \sa RSA_private_decrypt(3)
71 **/
72 int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
73 int rsa_inlen)
74 {
75 RSA *rsa;
76 int ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
77
78 if (ret < 0)
79 return ret;
80 ret = RSA_private_decrypt(rsa_inlen, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
81 return (ret > 0)? ret : -E_DECRYPT;
82 }
83
84 /**
85 * decrypt the challenge number sent by para_server
86 *
87 * \param key_file full path of the rsa key
88 * \param challenge_nr result is stored here
89 * \param inbuf the input buffer
90 * \param rsa_inlen the length of \a inbuf
91 *
92 * \return positive on success, negative on errors
93 *
94 * \sa para_decrypt_buffer()
95 */
96 int para_decrypt_challenge(char *key_file, long unsigned *challenge_nr,
97 unsigned char *inbuf, int rsa_inlen)
98 {
99 unsigned char *rsa_out = OPENSSL_malloc(rsa_inlen + 1);
100 int ret = para_decrypt_buffer(key_file, rsa_out, inbuf, rsa_inlen);
101
102 if (ret >= 0) {
103 rsa_out[ret] = '\0';
104 ret = sscanf((char *)rsa_out, "%lu", challenge_nr) == 1?
105 1 : -E_CHALLENGE;
106 }
107 OPENSSL_free(rsa_out);
108 return ret;
109 }
110
111 /**
112 * encrypt a buffer using an RSA key
113 *
114 * \param rsa: public rsa key
115 * \param inbuf the input buffer
116 * \param len the length of \a inbuf
117 * \param outbuf the output buffer
118 *
119 * \return The size of the encrypted data on success, negative on errors
120 *
121 * \sa RSA_public_encrypt(3)
122 */
123 int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
124 const unsigned len, unsigned char *outbuf)
125 {
126 int ret = RSA_public_encrypt(len, inbuf, outbuf, rsa,
127 RSA_PKCS1_PADDING);
128 return ret < 0? -E_ENCRYPT : ret;
129 }
130
131 /**
132 * encrypt the given challenge number
133 *
134 * \param rsa: public rsa key
135 * \param challenge_nr the number to be encrypted
136 * \param outbuf the output buffer
137 *
138 * \a outbuf must be at least 64 bytes long
139 *
140 * \return The size of the encrypted data on success, negative on errors
141 *
142 * \sa para_encrypt_buffer()
143 *
144 */
145 int para_encrypt_challenge(RSA* rsa, long unsigned challenge_nr,
146 unsigned char *outbuf)
147 {
148 unsigned char *inbuf = (unsigned char*) make_message("%lu", challenge_nr);
149 int ret = para_encrypt_buffer(rsa, inbuf, strlen((char *)inbuf), outbuf);
150 free(inbuf);
151 return ret;
152 }
153