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1
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'use strict';
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2
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3
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const baseEncodeTables = {
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4
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26: 'abcdefghijklmnopqrstuvwxyz',
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5
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32: '123456789abcdefghjkmnpqrstuvwxyz', // no 0lio
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6
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36: '0123456789abcdefghijklmnopqrstuvwxyz',
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7
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49: 'abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ', // no lIO
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8
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52: 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ',
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9
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58: '123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ', // no 0lIO
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10
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62: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ',
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11
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64: '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-_',
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12
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};
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13
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14
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function encodeBufferToBase(buffer, base) {
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15
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const encodeTable = baseEncodeTables[base];
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16
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if (!encodeTable) {
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17
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throw new Error('Unknown encoding base' + base);
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18
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}
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19
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20
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const readLength = buffer.length;
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21
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const Big = require('big.js');
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22
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23
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Big.RM = Big.DP = 0;
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24
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let b = new Big(0);
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25
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26
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for (let i = readLength - 1; i >= 0; i--) {
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27
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b = b.times(256).plus(buffer[i]);
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28
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}
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29
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30
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let output = '';
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31
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while (b.gt(0)) {
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32
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output = encodeTable[b.mod(base)] + output;
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33
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b = b.div(base);
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34
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}
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35
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36
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Big.DP = 20;
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37
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Big.RM = 1;
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38
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39
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return output;
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40
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}
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41
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42
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function getHashDigest(buffer, hashType, digestType, maxLength) {
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43
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hashType = hashType || 'md5';
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44
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maxLength = maxLength || 9999;
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45
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46
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const hash = require('crypto').createHash(hashType);
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47
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48
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hash.update(buffer);
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49
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50
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if (
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51
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digestType === 'base26' ||
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52
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digestType === 'base32' ||
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53
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digestType === 'base36' ||
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54
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digestType === 'base49' ||
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55
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digestType === 'base52' ||
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56
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digestType === 'base58' ||
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57
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digestType === 'base62' ||
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58
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digestType === 'base64'
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59
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) {
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60
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return encodeBufferToBase(hash.digest(), digestType.substr(4)).substr(
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61
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0,
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62
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maxLength
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63
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);
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64
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} else {
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65
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return hash.digest(digestType || 'hex').substr(0, maxLength);
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66
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}
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67
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}
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68
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69
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module.exports = getHashDigest;
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