2 * Copyright (C) 2005-2011 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file crypt_common.c Crypto functions independent of openssl/libgcrypt. */
15 #include "crypt_backend.h"
18 /** If the key begins with this text, we treat it as an ssh key. */
19 #define KEY_TYPE_TXT "ssh-rsa"
22 * Check if given buffer starts with a ssh rsa key signature.
24 * \param data The buffer.
25 * \param size Number of data bytes.
27 * \return Number of header bytes to be skipped on success, zero if
28 * ssh rsa signature was not found.
30 size_t is_ssh_rsa_key(char *data
, size_t size
)
34 if (size
< strlen(KEY_TYPE_TXT
) + 2)
36 cp
= memchr(data
, ' ', size
);
39 if (strncmp(KEY_TYPE_TXT
, data
, strlen(KEY_TYPE_TXT
)))
42 if (cp
>= data
+ size
)
50 * This base64/uudecode stuff below is taken from openssh-5.2p1, Copyright (c)
51 * 1996 by Internet Software Consortium. Portions Copyright (c) 1995 by
52 * International Business Machines, Inc.
55 static const char Base64
[] =
56 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
57 static const char Pad64
= '=';
60 * base64-decode a buffer.
62 * \param src The buffer to decode.
63 * \param target Result is stored here.
64 * \param targsize Number of bytes of \a target.
66 * Skips all whitespace anywhere. Converts characters, four at a time, starting
67 * at (or after) src from base - 64 numbers into three 8 bit bytes in the
70 * \return The number of data bytes stored at the target, -E_BASE64 on errors.
72 int base64_decode(char const *src
, unsigned char *target
, size_t targsize
)
74 unsigned int tarindex
, state
;
81 while ((ch
= *src
++) != '\0') {
82 if (para_isspace(ch
)) /* Skip whitespace anywhere. */
88 pos
= strchr(Base64
, ch
);
89 if (pos
== 0) /* A non-base64 character. */
95 if (tarindex
>= targsize
)
97 target
[tarindex
] = (pos
- Base64
) << 2;
103 if (tarindex
+ 1 >= targsize
)
105 target
[tarindex
] |= (pos
- Base64
) >> 4;
106 target
[tarindex
+1] = ((pos
- Base64
) & 0x0f)
114 if (tarindex
+ 1 >= targsize
)
116 target
[tarindex
] |= (pos
- Base64
) >> 2;
117 target
[tarindex
+1] = ((pos
- Base64
) & 0x03)
125 if (tarindex
>= targsize
)
127 target
[tarindex
] |= (pos
- Base64
);
136 * We are done decoding Base-64 chars. Let's see if we ended
137 * on a byte boundary, and/or with erroneous trailing characters.
140 if (ch
== Pad64
) { /* We got a pad char. */
141 ch
= *src
++; /* Skip it, get next. */
143 case 0: /* Invalid = in first position */
144 case 1: /* Invalid = in second position */
147 case 2: /* Valid, means one byte of info */
148 /* Skip any number of spaces. */
149 for (; ch
!= '\0'; ch
= *src
++)
152 /* Make sure there is another trailing = sign. */
155 ch
= *src
++; /* Skip the = */
156 /* Fall through to "single trailing =" case. */
159 case 3: /* Valid, means two bytes of info */
161 * We know this char is an =. Is there anything but
162 * whitespace after it?
164 for (; ch
!= '\0'; ch
= *src
++)
169 * Now make sure for cases 2 and 3 that the "extra"
170 * bits that slopped past the last full byte were
171 * zeros. If we don't check them, they become a
172 * subliminal channel.
174 if (target
&& target
[tarindex
] != 0)
179 * We ended by seeing the end of the string. Make sure we
180 * have no partial bytes lying around.
192 * \param src The buffer to decode.
193 * \param target Result buffer.
194 * \param targsize The length of \a target in bytes.
196 * This is just a simple wrapper for base64_decode() which strips whitespace.
198 * \return The return value of the underlying call to base64_decode().
200 int uudecode(const char *src
, unsigned char *target
, size_t targsize
)
205 /* copy the 'readonly' source */
206 encoded
= para_strdup(src
);
207 /* skip whitespace and data */
208 for (p
= encoded
; *p
== ' ' || *p
== '\t'; p
++)
210 for (; *p
!= '\0' && *p
!= ' ' && *p
!= '\t'; p
++)
212 /* and remove trailing whitespace because base64_decode needs this */
214 len
= base64_decode(encoded
, target
, targsize
);
220 * Read a 4-byte number from a buffer in big-endian format.
222 * \param vp The buffer.
224 * The byte-order of the buffer is expected to be big-endian, unlike read_u32()
225 * of portable_io.h which expects little endian.
227 * \return The 32 bit number given by \a vp.
229 uint32_t read_ssh_u32(const void *vp
)
231 const unsigned char *p
= (const unsigned char *)vp
;
234 v
= (uint32_t)p
[0] << 24;
235 v
|= (uint32_t)p
[1] << 16;
236 v
|= (uint32_t)p
[2] << 8;
243 * Sanity checks for the header of an ssh key.
245 * \param blob The buffer.
246 * \param blen The number of bytes of \a blob.
248 * This performs some checks to make sure we really have an ssh key. It also
249 * computes the offset in bytes of the start of the key values (modulus,
252 * \return The number of bytes to skip until the start of the first encoded
253 * number (usually 11).
255 int check_ssh_key_header(const unsigned char *blob
, int blen
)
257 const unsigned char *p
= blob
, *end
= blob
+ blen
;
261 return -E_SSH_KEY_HEADER
;
262 rlen
= read_ssh_u32(p
);
265 return -E_SSH_KEY_HEADER
;
267 return -E_SSH_KEY_HEADER
;
268 if (rlen
< strlen(KEY_TYPE_TXT
))
269 return -E_SSH_KEY_HEADER
;
270 PARA_DEBUG_LOG("type: %s, rlen: %d\n", p
, rlen
);
271 if (strncmp((char *)p
, KEY_TYPE_TXT
, strlen(KEY_TYPE_TXT
)))
272 return -E_SSH_KEY_HEADER
;
277 * Check existence and permissions of a key file.
279 * \param file The path of the key file.
280 * \param private_key Whether this is a private key.
282 * This checks whether the file exists. If it is a private key, we additionally
283 * check that the permissions are restrictive enough. It is considered an error
284 * if we own the file and it is readable for others.
288 int check_key_file(const char *file
, bool private_key
)
292 if (stat(file
, &st
) != 0)
293 return -ERRNO_TO_PARA_ERROR(errno
);
296 if ((st
.st_uid
== getuid()) && (st
.st_mode
& 077) != 0)
301 void hash_to_asc(unsigned char *hash
, char *asc
)
304 const char hexchar
[] = "0123456789abcdef";
306 for (i
= 0; i
< HASH_SIZE
; i
++) {
307 asc
[2 * i
] = hexchar
[hash
[i
] >> 4];
308 asc
[2 * i
+ 1] = hexchar
[hash
[i
] & 0xf];
310 asc
[2 * HASH_SIZE
] = '\0';
313 int hash_compare(unsigned char *h1
, unsigned char *h2
)
317 for (i
= 0; i
< HASH_SIZE
; i
++) {
326 int sc_recv_buffer(struct stream_cipher_context
*scc
, char *buf
, size_t size
)
331 n
= sc_recv_bin_buffer(scc
, buf
, size
- 1);
339 int sc_send_buffer(struct stream_cipher_context
*scc
, char *buf
)
341 return sc_send_bin_buffer(scc
, buf
, strlen(buf
));
344 __printf_2_3
int sc_send_va_buffer(struct stream_cipher_context
*scc
,
345 const char *fmt
, ...)
350 PARA_VSPRINTF(fmt
, msg
);
351 ret
= sc_send_buffer(scc
, msg
);