OLD | NEW |
1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 library crypto.base64; | 5 library crypto.base64; |
6 | 6 |
7 import 'dart:convert'; | 7 import 'dart:convert'; |
8 import 'dart:typed_data'; | 8 |
| 9 import 'base64/decoder.dart'; |
| 10 import 'base64/encoder.dart'; |
9 | 11 |
10 /// An instance of the default implementation of [Base64Codec]. | 12 /// An instance of the default implementation of [Base64Codec]. |
11 /// | 13 /// |
12 /// This provides convenient access to most common Base64 use-cases. | 14 /// This provides convenient access to most common Base64 use-cases. |
13 const Base64Codec BASE64 = const Base64Codec(); | 15 const Base64Codec BASE64 = const Base64Codec(); |
14 | 16 |
15 /// A mapping from ASCII character codes to their corresponding Base64 values. | |
16 /// | |
17 /// Characters with a value of -2 are invalid. Characters with a value of -1 | |
18 /// should be ignored. The padding character, "=", is represented as 0. | |
19 const List<int> _decodeTable = const [ | |
20 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -1, -2, -2, -1, -2, -2, | |
21 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, | |
22 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, 62, -2, 62, -2, 63, | |
23 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -2, -2, -2, 0, -2, -2, | |
24 -2, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, | |
25 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -2, -2, -2, -2, 63, | |
26 -2, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, | |
27 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -2, -2, -2, -2, -2, | |
28 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, | |
29 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, | |
30 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, | |
31 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, | |
32 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, | |
33 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, | |
34 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, | |
35 -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2 | |
36 ]; | |
37 | |
38 /// A String representing a mapping from numbers between 0 and 63, inclusive, to | |
39 /// their corresponding encoded character. | |
40 /// | |
41 /// This is the table for URL-safe encodings. | |
42 const String _encodeTableUrlSafe = | |
43 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; | |
44 | |
45 /// A String representing a mapping from numbers between 0 and 63, inclusive, to | |
46 /// their corresponding encoded character. | |
47 /// | |
48 /// This is the table for URL-unsafe encodings. | |
49 const String _encodeTable = | |
50 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; | |
51 | |
52 /// The line length for Base64 strings with line separators. | |
53 const int _LINE_LENGTH = 76; | |
54 | |
55 /// A carriage return. | |
56 const int _CR = 13; // '\r' | |
57 | |
58 /// A line feed. | |
59 const int _LF = 10; // '\n' | |
60 | |
61 /// The byte sequence representing non-URL-encoded padding. | |
62 const List<int> _PAD_BYTES = const [61]; // '=' | |
63 | |
64 /// The byte sequence representing URL-encoded padding. | |
65 const List<int> _ENCODED_PAD_BYTES = const [37, 51, 68]; // '%3D' | |
66 | |
67 /// The string representing non-URL-encoded padding. | |
68 const String _PAD = "="; | |
69 | |
70 /// The string representing URL-encoded padding. | |
71 const String _ENCODED_PAD = "%3D"; | |
72 | |
73 /// A codec that converts between binary data and [Base64][rfc]-encoded strings. | 17 /// A codec that converts between binary data and [Base64][rfc]-encoded strings. |
74 /// | 18 /// |
75 /// [rfc]: https://tools.ietf.org/html/rfc4648 | 19 /// [rfc]: https://tools.ietf.org/html/rfc4648 |
76 class Base64Codec extends Codec<List<int>, String> { | 20 class Base64Codec extends Codec<List<int>, String> { |
77 final bool _urlSafe; | 21 final bool _urlSafe; |
78 final bool _addLineSeparator; | 22 final bool _addLineSeparator; |
79 final bool _encodePaddingCharacter; | 23 final bool _encodePaddingCharacter; |
80 | 24 |
81 /// Creates a new [Base64Codec]. | 25 /// Creates a new [Base64Codec]. |
82 /// | 26 /// |
(...skipping 34 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
117 /// | 61 /// |
118 /// Any flags passed to this method take precedence over the flags passed to | 62 /// Any flags passed to this method take precedence over the flags passed to |
119 /// the codec itself. | 63 /// the codec itself. |
120 String encode(List<int> bytes, | 64 String encode(List<int> bytes, |
121 {bool urlSafe, bool addLineSeparator, bool encodePaddingCharacter}) { | 65 {bool urlSafe, bool addLineSeparator, bool encodePaddingCharacter}) { |
122 if (urlSafe == null) urlSafe = _urlSafe; | 66 if (urlSafe == null) urlSafe = _urlSafe; |
123 if (addLineSeparator == null) addLineSeparator = _addLineSeparator; | 67 if (addLineSeparator == null) addLineSeparator = _addLineSeparator; |
124 if (encodePaddingCharacter == null) { | 68 if (encodePaddingCharacter == null) { |
125 encodePaddingCharacter = _encodePaddingCharacter; | 69 encodePaddingCharacter = _encodePaddingCharacter; |
126 } | 70 } |
| 71 |
127 return new Base64Encoder( | 72 return new Base64Encoder( |
128 urlSafe: urlSafe, | 73 urlSafe: urlSafe, |
129 addLineSeparator: addLineSeparator, | 74 addLineSeparator: addLineSeparator, |
130 encodePaddingCharacter: encodePaddingCharacter).convert(bytes); | 75 encodePaddingCharacter: encodePaddingCharacter).convert(bytes); |
131 } | 76 } |
132 | 77 |
133 Base64Encoder get encoder => new Base64Encoder( | 78 Base64Encoder get encoder => new Base64Encoder( |
134 urlSafe: _urlSafe, | 79 urlSafe: _urlSafe, |
135 addLineSeparator: _addLineSeparator, | 80 addLineSeparator: _addLineSeparator, |
136 encodePaddingCharacter: _encodePaddingCharacter); | 81 encodePaddingCharacter: _encodePaddingCharacter); |
137 | 82 |
138 Base64Decoder get decoder => new Base64Decoder(); | 83 Base64Decoder get decoder => const Base64Decoder(); |
139 } | 84 } |
140 | |
141 /// An encoder that converts sequences of bytes to strings using [Base64][rfc]. | |
142 /// | |
143 /// [rfc]: https://tools.ietf.org/html/rfc4648 | |
144 class Base64Encoder extends Converter<List<int>, String> { | |
145 /// Whether this encoder generates URL-safe strings. | |
146 final bool _urlSafe; | |
147 | |
148 /// Whether this encoder adds line breaks to the output. | |
149 final bool _addLineSeparator; | |
150 | |
151 /// Whether this encoder URL-encodes trailing padding characters. | |
152 final bool _encodePaddingCharacter; | |
153 | |
154 /// The sequence of bytes to use as a padding character. | |
155 final List<int> _pad; | |
156 | |
157 /// Creates a new [Base64Encoder]. | |
158 /// | |
159 /// The default [BASE64.encoder] will be good enough for most cases. A new | |
160 /// codec only needs to be instantiated when you want to do multiple | |
161 /// conversions with the same configuration. | |
162 /// | |
163 /// If [urlSafe] is `true`, a URL-safe alphabet will be used. Specifically, | |
164 /// the characters `-` and `_` will be used instead of `+` and `/`. | |
165 /// | |
166 /// If [addLineSeparator] is `true`, `\r\n` line separators will be added | |
167 /// every 76 characters. | |
168 /// | |
169 /// If [encodePaddingCharacter] is `true`, the padding character `=` will be | |
170 /// written as `%3D`. | |
171 const Base64Encoder( | |
172 {bool urlSafe: false, | |
173 bool addLineSeparator: false, | |
174 bool encodePaddingCharacter: false}) | |
175 : _urlSafe = urlSafe, | |
176 _addLineSeparator = addLineSeparator, | |
177 _encodePaddingCharacter = encodePaddingCharacter, | |
178 _pad = encodePaddingCharacter == true ? _ENCODED_PAD_BYTES : _PAD_BYTES; | |
179 | |
180 /// Converts [bytes] to Base64. | |
181 /// | |
182 /// If [start] and [end] are provided, only the sublist `bytes.sublist(start, | |
183 /// end)` is converted. | |
184 String convert(List<int> bytes, [int start = 0, int end]) { | |
185 int bytes_length = bytes.length; | |
186 RangeError.checkValidRange(start, end, bytes_length); | |
187 if (end == null) end = bytes_length; | |
188 int length = end - start; | |
189 if (length == 0) { | |
190 return ""; | |
191 } | |
192 final String lookup = _urlSafe ? _encodeTableUrlSafe : _encodeTable; | |
193 // Size of 24 bit chunks. | |
194 final int remainderLength = length.remainder(3); | |
195 final int chunkLength = length - remainderLength; | |
196 // Size of base output. | |
197 int baseOutputLength = ((length ~/ 3) * 4); | |
198 int remainderOutputLength; | |
199 if (_encodePaddingCharacter) { | |
200 remainderOutputLength = ((remainderLength > 0) ? 6 : 0); | |
201 } else { | |
202 remainderOutputLength = ((remainderLength > 0) ? 4 : 0); | |
203 } | |
204 | |
205 int outputLength = baseOutputLength + remainderOutputLength; | |
206 // Add extra for line separators. | |
207 if (_addLineSeparator) { | |
208 outputLength += ((outputLength - 1) ~/ _LINE_LENGTH) << 1; | |
209 } | |
210 List<int> out = new List<int>(outputLength); | |
211 | |
212 // Encode 24 bit chunks. | |
213 int j = 0, i = start, c = 0; | |
214 while (i < chunkLength) { | |
215 int x = ((bytes[i++] << 16) & 0x00FFFFFF) | | |
216 ((bytes[i++] << 8) & 0x00FFFFFF) | | |
217 bytes[i++]; | |
218 out[j++] = lookup.codeUnitAt(x >> 18); | |
219 out[j++] = lookup.codeUnitAt((x >> 12) & 0x3F); | |
220 out[j++] = lookup.codeUnitAt((x >> 6) & 0x3F); | |
221 out[j++] = lookup.codeUnitAt(x & 0x3F); | |
222 // Add optional line separator for each 76 char output. | |
223 if (_addLineSeparator && ++c == 19 && j < outputLength - 2) { | |
224 out[j++] = _CR; | |
225 out[j++] = _LF; | |
226 c = 0; | |
227 } | |
228 } | |
229 | |
230 // If input length if not a multiple of 3, encode remaining bytes and | |
231 // add padding. | |
232 if (remainderLength == 1) { | |
233 int x = bytes[i]; | |
234 out[j++] = lookup.codeUnitAt(x >> 2); | |
235 out[j++] = lookup.codeUnitAt((x << 4) & 0x3F); | |
236 out.setRange(j, j + _pad.length, _pad); | |
237 out.setRange(j + _pad.length, j + 2 * _pad.length, _pad); | |
238 } else if (remainderLength == 2) { | |
239 int x = bytes[i]; | |
240 int y = bytes[i + 1]; | |
241 out[j++] = lookup.codeUnitAt(x >> 2); | |
242 out[j++] = lookup.codeUnitAt(((x << 4) | (y >> 4)) & 0x3F); | |
243 out[j++] = lookup.codeUnitAt((y << 2) & 0x3F); | |
244 out.setRange(j, j + _pad.length, _pad); | |
245 } | |
246 | |
247 return new String.fromCharCodes(out); | |
248 } | |
249 | |
250 _Base64EncoderSink startChunkedConversion(Sink<String> sink) { | |
251 StringConversionSink stringSink; | |
252 if (sink is StringConversionSink) { | |
253 stringSink = sink; | |
254 } else { | |
255 stringSink = new StringConversionSink.from(sink); | |
256 } | |
257 return new _Base64EncoderSink(stringSink, _urlSafe, _addLineSeparator); | |
258 } | |
259 } | |
260 | |
261 /// A [ChunkedConversionSink] for encoding chunks of data to Base64. | |
262 class _Base64EncoderSink extends ChunkedConversionSink<List<int>> { | |
263 /// The encoder used to encode each chunk. | |
264 final Base64Encoder _encoder; | |
265 | |
266 /// The underlying sink to which to emit the encoded strings. | |
267 final ChunkedConversionSink<String> _outSink; | |
268 | |
269 /// The buffer of as-yet-unconverted bytes. | |
270 /// | |
271 /// This is used to ensure that we don't generate interstitial padding | |
272 /// characters. | |
273 final List<int> _buffer = new List<int>(); | |
274 | |
275 /// The length of [_buffer]; that is, the number of unconverted bytes. | |
276 int _bufferCount = 0; | |
277 | |
278 _Base64EncoderSink(this._outSink, urlSafe, addLineSeparator) | |
279 : _encoder = new Base64Encoder( | |
280 urlSafe: urlSafe, addLineSeparator: addLineSeparator); | |
281 | |
282 void add(List<int> chunk) { | |
283 var nextBufferCount = (chunk.length + _bufferCount) % 3; | |
284 | |
285 int decodableLength = _bufferCount + chunk.length - nextBufferCount; | |
286 | |
287 if (_bufferCount + chunk.length > _buffer.length) { | |
288 _buffer.replaceRange(_bufferCount, _buffer.length, | |
289 chunk.sublist(0, _buffer.length - _bufferCount)); | |
290 _buffer.addAll(chunk.sublist(_buffer.length - _bufferCount)); | |
291 } else { | |
292 _buffer.replaceRange(_bufferCount, _bufferCount + chunk.length, chunk); | |
293 } | |
294 | |
295 _outSink.add(_encoder.convert(_buffer, 0, decodableLength)); | |
296 _buffer.removeRange(0, decodableLength); | |
297 _bufferCount = nextBufferCount; | |
298 } | |
299 | |
300 void close() { | |
301 if (_bufferCount > 0) { | |
302 _outSink.add(_encoder.convert(_buffer.sublist(0, _bufferCount))); | |
303 } | |
304 _outSink.close(); | |
305 } | |
306 } | |
307 | |
308 /// An encoder that converts [Base64][rfc] strings to sequences of bytes. | |
309 /// | |
310 /// [rfc]: https://tools.ietf.org/html/rfc4648 | |
311 class Base64Decoder extends Converter<String, List<int>> { | |
312 const Base64Decoder(); | |
313 | |
314 List<int> convert(String input) { | |
315 int length = input.length; | |
316 if (length == 0) { | |
317 return new Uint8List(0); | |
318 } | |
319 | |
320 int normalLength = 0; | |
321 int i = 0; | |
322 // Count '\r', '\n' and illegal characters, check if | |
323 // '/', '+' / '-', '_' are used consistently, for illegal characters, | |
324 // throw an exception. | |
325 | |
326 while (i < length) { | |
327 int codeUnit = input.codeUnitAt(i); | |
328 int c = _decodeTable[codeUnit]; | |
329 if (c == -2) { | |
330 if (codeUnit == _ENCODED_PAD_BYTES[0] && | |
331 i < length - 2 && | |
332 input.codeUnitAt(i + 1) == _ENCODED_PAD_BYTES[1] && | |
333 input.codeUnitAt(i + 2) == _ENCODED_PAD_BYTES[2]) { | |
334 normalLength++; | |
335 i += 2; | |
336 } else { | |
337 throw new FormatException('Invalid character', input, i); | |
338 } | |
339 } | |
340 if (c >= 0) normalLength++; | |
341 i++; | |
342 } | |
343 | |
344 if (normalLength % 4 != 0) { | |
345 throw new FormatException( | |
346 '''Size of Base 64 characters in Input | |
347 must be a multiple of 4''', | |
348 input, | |
349 normalLength); | |
350 } | |
351 | |
352 // Count pad characters. | |
353 int padLength = 0; | |
354 i = length - 1; | |
355 while (i >= 0) { | |
356 int currentCodeUnit = input.codeUnitAt(i); | |
357 if (currentCodeUnit == _ENCODED_PAD_BYTES[2] && | |
358 i >= 2 && | |
359 input.codeUnitAt(i - 1) == _ENCODED_PAD_BYTES[1] && | |
360 input.codeUnitAt(i - 2) == _ENCODED_PAD_BYTES[0]) { | |
361 padLength++; | |
362 i -= 2; | |
363 } else if (_decodeTable[currentCodeUnit] > 0) { | |
364 break; | |
365 } else if (currentCodeUnit == _PAD_BYTES[0]) { | |
366 padLength++; | |
367 } | |
368 i--; | |
369 } | |
370 int outputLength = ((normalLength * 6) >> 3) - padLength; | |
371 List<int> out = new Uint8List(outputLength); | |
372 | |
373 for (int i = 0, o = 0; o < outputLength;) { | |
374 // Accumulate 4 valid 6 bit Base 64 characters into an int. | |
375 int x = 0; | |
376 for (int j = 4; j > 0;) { | |
377 int c = _decodeTable[input.codeUnitAt(i++)]; | |
378 if (c >= 0) { | |
379 x = ((x << 6) & 0x00FFFFFF) | c; | |
380 j--; | |
381 } | |
382 } | |
383 out[o++] = x >> 16; | |
384 if (o < outputLength) { | |
385 out[o++] = (x >> 8) & 0xFF; | |
386 if (o < outputLength) out[o++] = x & 0xFF; | |
387 } | |
388 } | |
389 | |
390 return out; | |
391 } | |
392 | |
393 _Base64DecoderSink startChunkedConversion(Sink<List<int>> sink) { | |
394 if (sink is! ByteConversionSink) { | |
395 sink = new ByteConversionSink.from(sink); | |
396 } | |
397 return new _Base64DecoderSink(sink); | |
398 } | |
399 } | |
400 | |
401 /// A [ChunkedConversionSink] for decoding chunks of Base64 strings to data. | |
402 class _Base64DecoderSink extends ChunkedConversionSink<String> { | |
403 /// The encoder used to decode each chunk. | |
404 final Base64Decoder _decoder = new Base64Decoder(); | |
405 | |
406 /// The underlying sink to which to emit the decoded strings. | |
407 final ChunkedConversionSink<List<int>> _outSink; | |
408 | |
409 /// The as-yet-unconverted text. | |
410 /// | |
411 /// This is used to handle a chunk stopping partway in the middle of a | |
412 /// URL-encoded `=` character. | |
413 String _unconverted = ""; | |
414 | |
415 _Base64DecoderSink(this._outSink); | |
416 | |
417 void add(String chunk) { | |
418 if (chunk.isEmpty) return; | |
419 if (_unconverted.isNotEmpty) { | |
420 chunk = _unconverted + chunk; | |
421 } | |
422 chunk = chunk.replaceAll(_ENCODED_PAD, _PAD); | |
423 int decodableLength = chunk.length; | |
424 // If chunk ends in "%" or "%3", it may be a partial encoded pad. | |
425 // If chunk is smaller than 4 characters, don't bother checking. | |
426 if (chunk.length > 3 && chunk.contains(_ENCODED_PAD[0], chunk.length - 2)) { | |
427 decodableLength = chunk.lastIndexOf(_ENCODED_PAD[0]); | |
428 } | |
429 decodableLength -= decodableLength % 4; | |
430 _unconverted = chunk.substring(decodableLength); | |
431 if (decodableLength > 0) { | |
432 _outSink.add(_decoder.convert(chunk.substring(0, decodableLength))); | |
433 } | |
434 } | |
435 | |
436 void close() { | |
437 if (_unconverted.isNotEmpty) { | |
438 _outSink.add(_decoder.convert(_unconverted)); | |
439 } | |
440 _outSink.close(); | |
441 } | |
442 } | |
OLD | NEW |