2 * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file crypt.h Public crypto interface. */
10 /** \cond used to distinguish between loading of private/public key */
11 #define LOAD_PUBLIC_KEY 0
12 #define LOAD_PRIVATE_KEY 1
13 #define CHALLENGE_SIZE 64
16 /* asymetric (public key) crypto */
18 /** Opaque structure for public and private keys. */
19 struct asymmetric_key;
22 * Encrypt a buffer using asymmetric keys.
24 * \param pub: The public key.
25 * \param inbuf The input buffer.
26 * \param len The length of \a inbuf.
27 * \param outbuf The output buffer.
29 * \return The size of the encrypted data on success, negative on errors.
31 int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
32 unsigned len, unsigned char *outbuf);
35 * Decrypt a buffer using a private key.
37 * \param key_file Full path of the key.
38 * \param outbuf The output buffer.
39 * \param inbuf The encrypted input buffer.
40 * \param inlen The length of \a inbuf.
42 * The \a outbuf must be large enough to hold at least 512 bytes.
44 * \return The size of the recovered plaintext on success, negative on errors.
46 int priv_decrypt(const char *key_file, unsigned char *outbuf,
47 unsigned char *inbuf, int inlen);
50 * Read an asymmetric key from a file.
52 * \param key_file The file containing the key.
53 * \param private if non-zero, read the private key, otherwise the public key.
54 * \param result The key structure is returned here.
56 * \return The size of the key on success, negative on errors.
58 int get_asymmetric_key(const char *key_file, int private,
59 struct asymmetric_key **result);
62 * Deallocate an asymmetric key structure.
64 * \param key Pointer to the key structure to free.
66 * This must be called for any key obtained by get_asymmetric_key().
68 void free_asymmetric_key(struct asymmetric_key *key);
72 * Fill a buffer with random content.
74 * \param buf The buffer to fill.
75 * \param num The size of \a buf in bytes.
77 * This function puts \a num cryptographically strong pseudo-random bytes into
78 * buf. If it can not guarantee an unpredictable byte sequence (for example
79 * because the PRNG has not been seeded with enough randomness) the function
80 * logs an error message and calls exit().
82 void get_random_bytes_or_die(unsigned char *buf, int num);
85 * Seed pseudo random number generators.
87 * This function seeds the PRNG used by random() with a random seed obtained
88 * from the crypto implementation. On errors, an error message is logged and
89 * the function calls exit().
91 * \sa \ref get_random_bytes_or_die(), srandom(3), random(3), \ref
94 void init_random_seed_or_die(void);
97 /** Opaque structure for stream ciphers. */
100 /** Number of bytes of the session key for stream ciphers. */
101 #define SESSION_KEY_LEN 32
104 * Used for client-server communication encryption.
106 * The traffic between (the forked child of) para_server and the remote client
107 * process is crypted by a symmetric session key. This structure contains the
108 * keys for the stream cipher and the file descriptor for which these keys
111 struct stream_cipher_context {
112 /** The socket file descriptor. */
114 /** Key used for receiving data. */
115 struct stream_cipher *recv;
116 /** Key used for sending data. */
117 struct stream_cipher *send;
121 * Allocate and initialize a stream cipher structure.
123 * \param data The key.
124 * \param len The size of the key.
126 * \return A new stream cipher structure.
128 struct stream_cipher *sc_new(const unsigned char *data, int len);
131 * Deallocate a stream cipher structure.
133 * \param sc A stream cipher previously obtained by sc_new().
135 void sc_free(struct stream_cipher *sc);
138 * Encrypt and send a buffer.
140 * \param scc The context.
141 * \param buf The buffer to send.
142 * \param len The size of \a buf in bytes.
144 * \return The return value of the underyling call to write_all().
146 * \sa \ref write_all(), RC4(3).
148 int sc_send_bin_buffer(struct stream_cipher_context *scc, char *buf,
152 * Encrypt and send a \p NULL-terminated buffer.
154 * \param scc The context.
155 * \param buf The buffer to send.
157 * \return The return value of the underyling call to sc_send_bin_buffer().
159 int sc_send_buffer(struct stream_cipher_context *scc, char *buf);
162 * Format, encrypt and send a buffer.
164 * \param scc The context.
165 * \param fmt A format string.
167 * \return The return value of the underyling call to sc_send_buffer().
169 __printf_2_3 int sc_send_va_buffer(struct stream_cipher_context *scc,
170 const char *fmt, ...);
173 * Receive a buffer and decrypt it.
175 * \param scc The context.
176 * \param buf The buffer to write the decrypted data to.
177 * \param size The size of \a buf.
179 * \return The number of bytes received on success, negative on errors, zero if
180 * the peer has performed an orderly shutdown.
182 * \sa recv(2), RC4(3).
184 int sc_recv_bin_buffer(struct stream_cipher_context *scc, char *buf,
188 * Receive a buffer, decrypt it and write terminating NULL byte.
190 * \param scc The context.
191 * \param buf The buffer to write the decrypted data to.
192 * \param size The size of \a buf.
194 * Read at most \a size - 1 bytes from file descriptor given by \a scc, decrypt
195 * the received data and write a NULL byte at the end of the decrypted data.
197 * \return The return value of the underlying call to \ref
198 * sc_recv_bin_buffer().
200 int sc_recv_buffer(struct stream_cipher_context *scc, char *buf, size_t size);
203 /** Size of the hash value in bytes. */
208 * Compute the hash of the given input data.
210 * \param data Pointer to the data to compute the hash value from.
211 * \param len The length of \a data in bytes.
212 * \param hash Result pointer.
214 * \a hash must point to an area at least \p HASH_SIZE bytes large.
216 * \sa sha(3), openssl(1).
218 void hash_function(const char *data, unsigned long len, unsigned char *hash);
221 * Convert a hash value to ascii format.
223 * \param hash the hash value.
224 * \param asc Result pointer.
226 * \a asc must point to an area of at least 2 * \p HASH_SIZE + 1 bytes which
227 * will be filled by the function with the ascii representation of the hash
228 * value given by \a hash, and a terminating \p NULL byte.
230 void hash_to_asc(unsigned char *hash, char *asc);
233 * Compare two hashes.
235 * \param h1 Pointer to the first hash value.
236 * \param h2 Pointer to the second hash value.
238 * \return 1, -1, or zero, depending on whether \a h1 is greater than,
239 * less than or equal to h2, respectively.
241 int hash_compare(unsigned char *h1, unsigned char *h2);