Commit | Line | Data |
---|---|---|
86530b38 AT |
1 | .\" Automatically generated by Pod::Man v1.34, Pod::Parser v1.13 |
2 | .\" | |
3 | .\" Standard preamble: | |
4 | .\" ======================================================================== | |
5 | .de Sh \" Subsection heading | |
6 | .br | |
7 | .if t .Sp | |
8 | .ne 5 | |
9 | .PP | |
10 | \fB\\$1\fR | |
11 | .PP | |
12 | .. | |
13 | .de Sp \" Vertical space (when we can't use .PP) | |
14 | .if t .sp .5v | |
15 | .if n .sp | |
16 | .. | |
17 | .de Vb \" Begin verbatim text | |
18 | .ft CW | |
19 | .nf | |
20 | .ne \\$1 | |
21 | .. | |
22 | .de Ve \" End verbatim text | |
23 | .ft R | |
24 | .fi | |
25 | .. | |
26 | .\" Set up some character translations and predefined strings. \*(-- will | |
27 | .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left | |
28 | .\" double quote, and \*(R" will give a right double quote. | will give a | |
29 | .\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to | |
30 | .\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C' | |
31 | .\" expand to `' in nroff, nothing in troff, for use with C<>. | |
32 | .tr \(*W-|\(bv\*(Tr | |
33 | .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' | |
34 | .ie n \{\ | |
35 | . ds -- \(*W- | |
36 | . ds PI pi | |
37 | . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch | |
38 | . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch | |
39 | . ds L" "" | |
40 | . ds R" "" | |
41 | . ds C` "" | |
42 | . ds C' "" | |
43 | 'br\} | |
44 | .el\{\ | |
45 | . ds -- \|\(em\| | |
46 | . ds PI \(*p | |
47 | . ds L" `` | |
48 | . ds R" '' | |
49 | 'br\} | |
50 | .\" | |
51 | .\" If the F register is turned on, we'll generate index entries on stderr for | |
52 | .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index | |
53 | .\" entries marked with X<> in POD. Of course, you'll have to process the | |
54 | .\" output yourself in some meaningful fashion. | |
55 | .if \nF \{\ | |
56 | . de IX | |
57 | . tm Index:\\$1\t\\n%\t"\\$2" | |
58 | .. | |
59 | . nr % 0 | |
60 | . rr F | |
61 | .\} | |
62 | .\" | |
63 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes | |
64 | .\" way too many mistakes in technical documents. | |
65 | .hy 0 | |
66 | .if n .na | |
67 | .\" | |
68 | .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). | |
69 | .\" Fear. Run. Save yourself. No user-serviceable parts. | |
70 | . \" fudge factors for nroff and troff | |
71 | .if n \{\ | |
72 | . ds #H 0 | |
73 | . ds #V .8m | |
74 | . ds #F .3m | |
75 | . ds #[ \f1 | |
76 | . ds #] \fP | |
77 | .\} | |
78 | .if t \{\ | |
79 | . ds #H ((1u-(\\\\n(.fu%2u))*.13m) | |
80 | . ds #V .6m | |
81 | . ds #F 0 | |
82 | . ds #[ \& | |
83 | . ds #] \& | |
84 | .\} | |
85 | . \" simple accents for nroff and troff | |
86 | .if n \{\ | |
87 | . ds ' \& | |
88 | . ds ` \& | |
89 | . ds ^ \& | |
90 | . ds , \& | |
91 | . ds ~ ~ | |
92 | . ds / | |
93 | .\} | |
94 | .if t \{\ | |
95 | . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" | |
96 | . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' | |
97 | . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' | |
98 | . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' | |
99 | . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' | |
100 | . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' | |
101 | .\} | |
102 | . \" troff and (daisy-wheel) nroff accents | |
103 | .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' | |
104 | .ds 8 \h'\*(#H'\(*b\h'-\*(#H' | |
105 | .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] | |
106 | .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' | |
107 | .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' | |
108 | .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] | |
109 | .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] | |
110 | .ds ae a\h'-(\w'a'u*4/10)'e | |
111 | .ds Ae A\h'-(\w'A'u*4/10)'E | |
112 | . \" corrections for vroff | |
113 | .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' | |
114 | .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' | |
115 | . \" for low resolution devices (crt and lpr) | |
116 | .if \n(.H>23 .if \n(.V>19 \ | |
117 | \{\ | |
118 | . ds : e | |
119 | . ds 8 ss | |
120 | . ds o a | |
121 | . ds d- d\h'-1'\(ga | |
122 | . ds D- D\h'-1'\(hy | |
123 | . ds th \o'bp' | |
124 | . ds Th \o'LP' | |
125 | . ds ae ae | |
126 | . ds Ae AE | |
127 | .\} | |
128 | .rm #[ #] #H #V #F C | |
129 | .\" ======================================================================== | |
130 | .\" | |
131 | .IX Title "CBC 3" | |
132 | .TH CBC 3 "2002-09-11" "perl v5.8.0" "User Contributed Perl Documentation" | |
133 | .SH "NAME" | |
134 | Crypt::CBC \- Encrypt Data with Cipher Block Chaining Mode | |
135 | .SH "SYNOPSIS" | |
136 | .IX Header "SYNOPSIS" | |
137 | .Vb 8 | |
138 | \& use Crypt::CBC; | |
139 | \& $cipher = Crypt::CBC->new( {'key' => 'my secret key', | |
140 | \& 'cipher' => 'Blowfish', | |
141 | \& 'iv' => '$KJh#(}q', | |
142 | \& 'regenerate_key' => 0, # default true | |
143 | \& 'padding' => 'space', | |
144 | \& 'prepend_iv' => 0 | |
145 | \& }); | |
146 | .Ve | |
147 | .PP | |
148 | .Vb 2 | |
149 | \& $ciphertext = $cipher->encrypt("This data is hush hush"); | |
150 | \& $plaintext = $cipher->decrypt($ciphertext); | |
151 | .Ve | |
152 | .PP | |
153 | .Vb 6 | |
154 | \& $cipher->start('encrypting'); | |
155 | \& open(F,"./BIG_FILE"); | |
156 | \& while (read(F,$buffer,1024)) { | |
157 | \& print $cipher->crypt($buffer); | |
158 | \& } | |
159 | \& print $cipher->finish; | |
160 | .Ve | |
161 | .SH "DESCRIPTION" | |
162 | .IX Header "DESCRIPTION" | |
163 | This module is a Perl-only implementation of the cryptographic cipher | |
164 | block chaining mode (\s-1CBC\s0). In combination with a block cipher such as | |
165 | \&\s-1DES\s0 or \s-1IDEA\s0, you can encrypt and decrypt messages of arbitrarily long | |
166 | length. The encrypted messages are compatible with the encryption | |
167 | format used by \fBSSLeay\fR. | |
168 | .PP | |
169 | To use this module, you will first create a Crypt::CBC cipher object with | |
170 | \&\fInew()\fR. At the time of cipher creation, you specify an encryption key | |
171 | to use and, optionally, a block encryption algorithm. You will then | |
172 | call the \fIstart()\fR method to initialize the encryption or decryption | |
173 | process, \fIcrypt()\fR to encrypt or decrypt one or more blocks of data, and | |
174 | lastly \fIfinish()\fR, to pad and encrypt the final block. For your | |
175 | convenience, you can call the \fIencrypt()\fR and \fIdecrypt()\fR methods to | |
176 | operate on a whole data value at once. | |
177 | .Sh "\fInew()\fP" | |
178 | .IX Subsection "new()" | |
179 | .Vb 7 | |
180 | \& $cipher = Crypt::CBC->new( {'key' => 'my secret key', | |
181 | \& 'cipher' => 'Blowfish', | |
182 | \& 'iv' => '$KJh#(}q', | |
183 | \& 'regenerate_key' => 0, # default true | |
184 | \& 'padding' => 'space', | |
185 | \& 'prepend_iv' => 0 | |
186 | \& }); | |
187 | .Ve | |
188 | .PP | |
189 | .Vb 2 | |
190 | \& # or (for compatibility with earlier versions) | |
191 | \& $cipher = new Crypt::CBC($key,$algorithm); | |
192 | .Ve | |
193 | .PP | |
194 | The \fInew()\fR method creates a new Crypt::CBC object. | |
195 | .PP | |
196 | You must provide an encryption/decryption key, which can be any series | |
197 | of characters of any length. If regenerate_key is not specified as a | |
198 | false value, the actual key used is derived from the \s-1MD5\s0 hash of the | |
199 | key you provide. The cipher is optional and will default to \s-1DES\s0 unless | |
200 | specified otherwise. You may use any compatible block encryption | |
201 | algorithm that you have installed. Currently, this includes Crypt::DES, | |
202 | Crypt::DES_EDE3, Crypt::IDEA, Crypt::Blowfish, and Crypt::Rijndael. You | |
203 | may refer to them using their full names (\*(L"Crypt::IDEA\*(R") or in | |
204 | abbreviated form (\*(L"\s-1IDEA\s0\*(R"). | |
205 | .PP | |
206 | An initialization vector may be specified, either by passing in a key of | |
207 | \&'iv' as an option to new, or by calling | |
208 | \&\f(CW$cipher\fR\->set_initialization_key($iv) before calling \f(CW$cipher\fR\->\fIstart()\fR. | |
209 | The \s-1IV\s0 will be ignored in decryption if the ciphertext is prepended by | |
210 | text which matches the regex /^RandomIV.{8}/, in which case the 8 | |
211 | characters following \*(L"RandomIV\*(R" will be used as the \s-1IV\s0. When encrypting, | |
212 | by default the ciphertext will be prepended with "RandomIV<\s-1IV\s0>\*(L" | |
213 | (16 bytes). To disable this, set 'prepend_iv' to a false value. The | |
214 | padding method can be specified by the 'padding' option. If no padding | |
215 | method is specified, PKCS#5 (\*(R"standard") padding is assumed. | |
216 | .Sh "\fIstart()\fP" | |
217 | .IX Subsection "start()" | |
218 | .Vb 2 | |
219 | \& $cipher->start('encrypting'); | |
220 | \& $cipher->start('decrypting'); | |
221 | .Ve | |
222 | .PP | |
223 | The \fIstart()\fR method prepares the cipher for a series of encryption or | |
224 | decryption steps, resetting the internal state of the cipher if | |
225 | necessary. You must provide a string indicating whether you wish to | |
226 | encrypt or decrypt. \*(L"E\*(R" or any word that begins with an \*(L"e\*(R" indicates | |
227 | encryption. \*(L"D\*(R" or any word that begins with a \*(L"d\*(R" indicates | |
228 | decryption. | |
229 | .Sh "\fIcrypt()\fP" | |
230 | .IX Subsection "crypt()" | |
231 | .Vb 1 | |
232 | \& $ciphertext = $cipher->crypt($plaintext); | |
233 | .Ve | |
234 | .PP | |
235 | After calling \fIstart()\fR, you should call \fIcrypt()\fR as many times as | |
236 | necessary to encrypt the desired data. | |
237 | .Sh "\fIfinish()\fP" | |
238 | .IX Subsection "finish()" | |
239 | .Vb 1 | |
240 | \& $ciphertext = $cipher->finish(); | |
241 | .Ve | |
242 | .PP | |
243 | The \s-1CBC\s0 algorithm must buffer data blocks inernally until they are | |
244 | even multiples of the encryption algorithm's blocksize (typically 8 | |
245 | bytes). After the last call to \fIcrypt()\fR you should call \fIfinish()\fR. | |
246 | This flushes the internal buffer and returns any leftover ciphertext. | |
247 | .PP | |
248 | In a typical application you will read the plaintext from a file or | |
249 | input stream and write the result to standard output in a loop that | |
250 | might look like this: | |
251 | .PP | |
252 | .Vb 4 | |
253 | \& $cipher = new Crypt::CBC('hey jude!'); | |
254 | \& $cipher->start('encrypting'); | |
255 | \& print $cipher->crypt($_) while <>; | |
256 | \& print $cipher->finish(); | |
257 | .Ve | |
258 | .Sh "\fIencrypt()\fP" | |
259 | .IX Subsection "encrypt()" | |
260 | .Vb 1 | |
261 | \& $ciphertext = $cipher->encrypt($plaintext) | |
262 | .Ve | |
263 | .PP | |
264 | This convenience function runs the entire sequence of \fIstart()\fR, \fIcrypt()\fR | |
265 | and \fIfinish()\fR for you, processing the provided plaintext and returning | |
266 | the corresponding ciphertext. | |
267 | .Sh "\fIdecrypt()\fP" | |
268 | .IX Subsection "decrypt()" | |
269 | .Vb 1 | |
270 | \& $plaintext = $cipher->decrypt($ciphertext) | |
271 | .Ve | |
272 | .PP | |
273 | This convenience function runs the entire sequence of \fIstart()\fR, \fIcrypt()\fR | |
274 | and \fIfinish()\fR for you, processing the provided ciphertext and returning | |
275 | the corresponding plaintext. | |
276 | .Sh "\fIencrypt_hex()\fP, \fIdecrypt_hex()\fP" | |
277 | .IX Subsection "encrypt_hex(), decrypt_hex()" | |
278 | .Vb 2 | |
279 | \& $ciphertext = $cipher->encrypt_hex($plaintext) | |
280 | \& $plaintext = $cipher->decrypt_hex($ciphertext) | |
281 | .Ve | |
282 | .PP | |
283 | These are convenience functions that operate on ciphertext in a | |
284 | hexadecimal representation. \fBencrypt_hex($plaintext)\fR is exactly | |
285 | equivalent to \fBunpack('H*',encrypt($plaintext))\fR. These functions | |
286 | can be useful if, for example, you wish to place the encrypted | |
287 | .Sh "\fIget_initialization_vector()\fP" | |
288 | .IX Subsection "get_initialization_vector()" | |
289 | .Vb 1 | |
290 | \& $iv = $cipher->get_initialization_vector() | |
291 | .Ve | |
292 | .PP | |
293 | This function will return the \s-1IV\s0 used in encryption and or decryption. | |
294 | This function may be useful to determine the random \s-1IV\s0 used when | |
295 | encrypting if none is specified in \fInew()\fR. The \s-1IV\s0 is not guaranteed to | |
296 | be set when encrypting until \fIstart()\fR is called, and when decrypting | |
297 | until \fIcrypt()\fR is called the first time. | |
298 | .Sh "\fIset_initialization_vector()\fP" | |
299 | .IX Subsection "set_initialization_vector()" | |
300 | .Vb 1 | |
301 | \& $cipher->set_initialization_vector('76543210') | |
302 | .Ve | |
303 | .PP | |
304 | This function sets the \s-1IV\s0 used in encryption and/or decryption. This | |
305 | function may be useful if the \s-1IV\s0 is not contained within the ciphertext | |
306 | string being decrypted, or if a particular \s-1IV\s0 is desired for encryption. | |
307 | If not set, a random \s-1IV\s0 will be generated. The \s-1IV\s0 is not guaranteed to | |
308 | be set when encrypting until \fIstart()\fR is called, and when decrypting | |
309 | until \fIcrypt()\fR is called the first time. | |
310 | .Sh "Padding methods" | |
311 | .IX Subsection "Padding methods" | |
312 | Use the 'padding' option to change the padding method. | |
313 | .PP | |
314 | When the last block of plaintext is shorter than the block size, | |
315 | it must be padded. Padding methods include: \*(L"standard\*(R" (i.e., PKCS#5), | |
316 | \&\*(L"oneandzeroes\*(R", \*(L"space\*(R", and \*(L"null\*(R". | |
317 | .PP | |
318 | .Vb 5 | |
319 | \& standard: (default) Binary safe | |
320 | \& pads with the number of bytes that should be truncated. So, if | |
321 | \& blocksize is 8, then "0A0B0C" will be padded with "05", resulting | |
322 | \& in "0A0B0C0505050505". If the final block is a full block of 8 | |
323 | \& bytes, then a whole block of "0808080808080808" is appended. | |
324 | .Ve | |
325 | .PP | |
326 | .Vb 4 | |
327 | \& oneandzeroes: Binary safe | |
328 | \& pads with "80" followed by as many "00" necessary to fill the | |
329 | \& block. If the last block is a full block and blocksize is 8, a | |
330 | \& block of "8000000000000000" will be appended. | |
331 | .Ve | |
332 | .PP | |
333 | .Vb 4 | |
334 | \& null: text only | |
335 | \& pads with as many "00" necessary to fill the block. If the last | |
336 | \& block is a full block and blocksize is 8, a block of | |
337 | \& "0000000000000000" will be appended. | |
338 | .Ve | |
339 | .PP | |
340 | .Vb 2 | |
341 | \& space: text only | |
342 | \& same as "null", but with "20". | |
343 | .Ve | |
344 | .PP | |
345 | Both the standard and oneandzeroes paddings are binary safe. The | |
346 | space and null paddings are recommended only for text data. Which | |
347 | type of padding you use depends on whether you wish to communicate | |
348 | with an external (non Crypt::CBC library). If this is the case, use | |
349 | whatever padding method is compatible. | |
350 | .PP | |
351 | You can also pass in a custom padding function. To do this, create a | |
352 | function that takes the arguments: | |
353 | .PP | |
354 | .Vb 1 | |
355 | \& $padded_block = function($block,$blocksize,$direction); | |
356 | .Ve | |
357 | .PP | |
358 | where \f(CW$block\fR is the current block of data, \f(CW$blocksize\fR is the size to | |
359 | pad it to, \f(CW$direction\fR is \*(L"e\*(R" for encrypting and \*(L"d\*(R" for decrypting, | |
360 | and \f(CW$padded_block\fR is the result after padding or depadding. | |
361 | .PP | |
362 | When encrypting, the function should always return a string of | |
363 | <blocksize> length, and when decrypting, can expect the string coming | |
364 | in to always be that length. See \fI_standard_padding()\fR, \fI_space_padding()\fR, | |
365 | \&\fI_null_padding()\fR, or \fI_oneandzeroes_padding()\fR in the source for examples. | |
366 | .PP | |
367 | Standard and oneandzeroes padding are recommended, as both space and | |
368 | null padding can potentially truncate more characters than they should. | |
369 | .SH "EXAMPLES" | |
370 | .IX Header "EXAMPLES" | |
371 | Two examples, des.pl and idea.pl can be found in the eg/ subdirectory | |
372 | of the Crypt-CBC distribution. These implement command-line \s-1DES\s0 and | |
373 | \&\s-1IDEA\s0 encryption algorithms. | |
374 | .SH "LIMITATIONS" | |
375 | .IX Header "LIMITATIONS" | |
376 | The encryption and decryption process is about a tenth the speed of | |
377 | the equivalent SSLeay programs (compiled C). This could be improved | |
378 | by implementing this module in C. It may also be worthwhile to | |
379 | optimize the \s-1DES\s0 and \s-1IDEA\s0 block algorithms further. | |
380 | .SH "BUGS" | |
381 | .IX Header "BUGS" | |
382 | Please report them. | |
383 | .SH "AUTHOR" | |
384 | .IX Header "AUTHOR" | |
385 | Lincoln Stein, lstein@cshl.org | |
386 | .PP | |
387 | This module is distributed under the \s-1ARTISTIC\s0 \s-1LICENSE\s0 using the same | |
388 | terms as Perl itself. | |
389 | .SH "SEE ALSO" | |
390 | .IX Header "SEE ALSO" | |
391 | \&\fIperl\fR\|(1), \fICrypt::DES\fR\|(3), \fICrypt::IDEA\fR\|(3), rfc2898 (PKCS#5) |