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
  50 int get_rsa_key(char *key_file, RSA **rsa, int private)
  51 {
  52         EVP_PKEY *key = load_key(key_file, private);
  53
  54         if (!key)
  55                 return (private == LOAD_PRIVATE_KEY)? -E_PRIVATE_KEY : -E_PUBLIC_KEY;
  56         *rsa = EVP_PKEY_get1_RSA(key);
  57         EVP_PKEY_free(key);
  58         if (!*rsa)
  59                 return -E_RSA;
  60         return RSA_size(*rsa);
  61 }
  62
  63 /**
  64  * decrypt a buffer using an RSA key
  65  *
  66  * \param key_file full path of the rsa key
  67  * \param outbuf the output buffer
  68  * \param inbuf the encrypted input buffer
  69  * \param rsa_inlen the length of \a inbuf
  70  *
  71  * The \a outbuf must be large enough to hold at least \a rsa_inlen bytes.
  72  *
  73  * \return The size of the recovered plaintext on success, negative on errors.
  74  *
  75  * \sa RSA_private_decrypt(3)
  76  **/
  77 int para_decrypt_buffer(char *key_file, unsigned char *outbuf, unsigned char *inbuf,
  78                         int rsa_inlen)
  79 {
  80         RSA *rsa;
  81         int ret = get_rsa_key(key_file, &rsa, LOAD_PRIVATE_KEY);
  82
  83         if (ret < 0)
  84                 return ret;
  85         ret = RSA_private_decrypt(rsa_inlen, inbuf, outbuf, rsa, RSA_PKCS1_PADDING);
  86         return (ret > 0)? ret : -E_DECRYPT;
  87 }
  88
  89 /**
  90  * decrypt the challenge number sent by para_server
  91  *
  92  * \param key_file full path of the rsa key
  93  * \param challenge_nr result is stored here
  94  * \param inbuf the input buffer
  95  * \param rsa_inlen the length of \a inbuf
  96  *
  97  * \return positive on success, negative on errors
  98  *
  99  * \sa para_decrypt_buffer()
 100  */
 101 int para_decrypt_challenge(char *key_file, long unsigned *challenge_nr,
 102                 unsigned char *inbuf, int rsa_inlen)
 103 {
 104         unsigned char *rsa_out = OPENSSL_malloc(rsa_inlen + 1);
 105         int ret = para_decrypt_buffer(key_file, rsa_out, inbuf, rsa_inlen);
 106
 107         if (ret >= 0) {
 108                 rsa_out[ret] = '\0';
 109                 ret = sscanf((char *)rsa_out, "%lu", challenge_nr) == 1?
 110                         1 : -E_CHALLENGE;
 111         }
 112         OPENSSL_free(rsa_out);
 113         return ret;
 114 }
 115
 116 /**
 117  * encrypt a buffer using an RSA key
 118  *
 119  * \param rsa: public rsa key
 120  * \param inbuf the input buffer
 121  * \param len the length of \a inbuf
 122  * \param outbuf the output buffer
 123  *
 124  * \return The size of the encrypted data on success, negative on errors
 125  *
 126  * \sa RSA_public_encrypt(3)
 127  */
 128 int para_encrypt_buffer(RSA *rsa, unsigned char *inbuf,
 129                 const unsigned len, unsigned char *outbuf)
 130 {
 131         int ret = RSA_public_encrypt(len, inbuf, outbuf, rsa,
 132                 RSA_PKCS1_PADDING);
 133         return ret < 0?  -E_ENCRYPT : ret;
 134 }
 135
 136 /**
 137  * encrypt the given challenge number
 138  *
 139  * \param rsa: public rsa key
 140  * \param challenge_nr the number to be encrypted
 141  * \param outbuf the output buffer
 142  *
 143  * \a outbuf must be at least 64 bytes long
 144  *
 145  * \return The size of the encrypted data on success, negative on errors
 146  *
 147  * \sa para_encrypt_buffer()
 148  *
 149  */
 150 int para_encrypt_challenge(RSA* rsa, long unsigned challenge_nr,
 151         unsigned char *outbuf)
 152 {
 153         unsigned char *inbuf = (unsigned char*) make_message("%lu", challenge_nr);
 154         int ret = para_encrypt_buffer(rsa, inbuf, strlen((char *)inbuf), outbuf);
 155         free(inbuf);
 156         return ret;
 157 }
 158