| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| part of crypto; |
| |
| abstract class _CryptoUtils { |
| static String bytesToHex(List<int> bytes) { |
| var result = new StringBuffer(); |
| for (var part in bytes) { |
| result.write('${part < 16 ? '0' : ''}${part.toRadixString(16)}'); |
| } |
| return result.toString(); |
| } |
| |
| static const int PAD = 61; // '=' |
| static const int CR = 13; // '\r' |
| static const int LF = 10; // '\n' |
| static const int LINE_LENGTH = 76; |
| |
| static const String _encodeTable = |
| "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| |
| static const String _encodeTableUrlSafe = |
| "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; |
| |
| // Lookup table used for finding Base 64 alphabet index of a given byte. |
| // -2 : Outside Base 64 alphabet. |
| // -1 : '\r' or '\n' |
| // 0 : = (Padding character). |
| // >0 : Base 64 alphabet index of given byte. |
| static const List<int> _decodeTable = |
| const [ -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -1, -2, -2, -1, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, 62, -2, 62, -2, 63, |
| 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -2, -2, -2, 0, -2, -2, |
| -2, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, |
| 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -2, -2, -2, -2, 63, |
| -2, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, |
| 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, |
| -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2 ]; |
| |
| static String bytesToBase64(List<int> bytes, |
| [bool urlSafe = false, |
| bool addLineSeparator = false]) { |
| int len = bytes.length; |
| if (len == 0) { |
| return ""; |
| } |
| final String lookup = urlSafe ? _encodeTableUrlSafe : _encodeTable; |
| // Size of 24 bit chunks. |
| final int remainderLength = len.remainder(3); |
| final int chunkLength = len - remainderLength; |
| // Size of base output. |
| int outputLen = ((len ~/ 3) * 4) + ((remainderLength > 0) ? 4 : 0); |
| // Add extra for line separators. |
| if (addLineSeparator) { |
| outputLen += ((outputLen - 1) ~/ LINE_LENGTH) << 1; |
| } |
| List<int> out = new List<int>(outputLen); |
| |
| // Encode 24 bit chunks. |
| int j = 0, i = 0, c = 0; |
| while (i < chunkLength) { |
| int x = ((bytes[i++] << 16) & 0xFFFFFF) | |
| ((bytes[i++] << 8) & 0xFFFFFF) | |
| bytes[i++]; |
| out[j++] = lookup.codeUnitAt(x >> 18); |
| out[j++] = lookup.codeUnitAt((x >> 12) & 0x3F); |
| out[j++] = lookup.codeUnitAt((x >> 6) & 0x3F); |
| out[j++] = lookup.codeUnitAt(x & 0x3f); |
| // Add optional line separator for each 76 char output. |
| if (addLineSeparator && ++c == 19 && j < outputLen - 2) { |
| out[j++] = CR; |
| out[j++] = LF; |
| c = 0; |
| } |
| } |
| |
| // If input length if not a multiple of 3, encode remaining bytes and |
| // add padding. |
| if (remainderLength == 1) { |
| int x = bytes[i]; |
| out[j++] = lookup.codeUnitAt(x >> 2); |
| out[j++] = lookup.codeUnitAt((x << 4) & 0x3F); |
| out[j++] = PAD; |
| out[j++] = PAD; |
| } else if (remainderLength == 2) { |
| int x = bytes[i]; |
| int y = bytes[i + 1]; |
| out[j++] = lookup.codeUnitAt(x >> 2); |
| out[j++] = lookup.codeUnitAt(((x << 4) | (y >> 4)) & 0x3F); |
| out[j++] = lookup.codeUnitAt((y << 2) & 0x3F); |
| out[j++] = PAD; |
| } |
| |
| return new String.fromCharCodes(out); |
| } |
| |
| static List<int> base64StringToBytes(String input) { |
| int len = input.length; |
| if (len == 0) { |
| return new List<int>(0); |
| } |
| |
| // Count '\r', '\n' and illegal characters, For illegal characters, |
| // throw an exception. |
| int extrasLen = 0; |
| for (int i = 0; i < len; i++) { |
| int c = _decodeTable[input.codeUnitAt(i)]; |
| if (c < 0) { |
| extrasLen++; |
| if(c == -2) { |
| throw new FormatException('Invalid character: ${input[i]}'); |
| } |
| } |
| } |
| |
| if ((len - extrasLen) % 4 != 0) { |
| throw new FormatException('''Size of Base 64 characters in Input |
| must be a multiple of 4. Input: $input'''); |
| } |
| |
| // Count pad characters. |
| int padLength = 0; |
| for (int i = len - 1; i >= 0; i--) { |
| int currentCodeUnit = input.codeUnitAt(i); |
| if (_decodeTable[currentCodeUnit] > 0) break; |
| if (currentCodeUnit == PAD) padLength++; |
| } |
| int outputLen = (((len - extrasLen) * 6) >> 3) - padLength; |
| List<int> out = new List<int>(outputLen); |
| |
| for (int i = 0, o = 0; o < outputLen;) { |
| // Accumulate 4 valid 6 bit Base 64 characters into an int. |
| int x = 0; |
| for (int j = 4; j > 0;) { |
| int c = _decodeTable[input.codeUnitAt(i++)]; |
| if (c >= 0) { |
| x = ((x << 6) & 0xFFFFFF) | c; |
| j--; |
| } |
| } |
| out[o++] = x >> 16; |
| if (o < outputLen) { |
| out[o++] = (x >> 8) & 0xFF; |
| if (o < outputLen) out[o++] = x & 0xFF; |
| } |
| } |
| return out; |
| } |
| |
| } |