├── README.md
└── crc32.htm


/README.md:
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 1 | #BiliBili 弹幕hash极速反查
 2 | 
 3 | 
 4 | 算法作者：MoePus
 5 | 
 6 | 
 7 | JS改编：esterTion
 8 | 
 9 | 
10 | License: [GFUL](https://www.cnbeining.com/gful-go-fuck-yourself-license-version-1/)
11 | 


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/crc32.htm:
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  1 | <meta charset=utf8><script>
  2 | var BiliBili_midcrc=function(){
  3 | 	'use strict';
  4 | 	const CRCPOLYNOMIAL = 0xEDB88320;
  5 | 	var startTime=performance.now(),
  6 | 	crctable=new Array(256),
  7 | 	create_table=function(){
  8 | 		var crcreg,
  9 | 		i,j;
 10 | 		for (i = 0; i < 256; ++i)
 11 | 		{
 12 | 			crcreg = i;
 13 | 			for (j = 0; j < 8; ++j)
 14 | 			{
 15 | 				if ((crcreg & 1) != 0)
 16 | 				{
 17 | 					crcreg = CRCPOLYNOMIAL ^ (crcreg >>> 1);
 18 | 				}
 19 | 				else
 20 | 				{
 21 | 					crcreg >>>= 1;
 22 | 				}
 23 | 			}
 24 | 			crctable[i] = crcreg;
 25 | 		}
 26 | 	},
 27 | 	crc32=function(input){
 28 | 		if(typeof(input)!='string')
 29 | 			input=input.toString();
 30 | 		var crcstart = 0xFFFFFFFF, len = input.length, index;
 31 | 		for(var i=0;i<len;++i){
 32 | 			index = (crcstart ^ input.charCodeAt(i)) & 0xff;
 33 | 			crcstart = (crcstart >>> 8) ^ crctable[index];
 34 | 		}
 35 | 		return crcstart;
 36 | 	},
 37 | 	crc32lastindex=function(input){
 38 | 		if(typeof(input)!='string')
 39 | 			input=input.toString();
 40 | 		var crcstart = 0xFFFFFFFF, len = input.length, index;
 41 | 		for(var i=0; i<len;++i){
 42 | 			index = (crcstart ^ input.charCodeAt(i)) & 0xff;
 43 | 			crcstart = (crcstart >>> 8) ^ crctable[index];
 44 | 		}
 45 | 		return index;
 46 | 	},
 47 | 	getcrcindex=function(t){
 48 | 		//if(t>0)
 49 | 			//t-=256;
 50 | 		for(var i=0;i<256;i++){
 51 | 			if(crctable[i] >>> 24 == t)
 52 | 				return i;
 53 | 		}
 54 | 		return -1;
 55 | 	},
 56 | 	deepCheck=function(i, index){
 57 | 		var tc=0x00,str='',
 58 | 		hash=crc32(i);
 59 | 		tc = hash & 0xff ^ index[2];
 60 | 		if (!(tc <= 57 && tc >= 48))
 61 | 			return [0];
 62 | 		str+=tc-48;
 63 | 		hash = crctable[index[2]] ^ (hash >>> 8);
 64 | 		tc = hash & 0xff ^ index[1];
 65 | 		if (!(tc <= 57 && tc >= 48))
 66 | 			return [0];
 67 | 		str+=tc-48;
 68 | 		hash = crctable[index[1]] ^ (hash >>> 8);
 69 | 		tc = hash & 0xff ^ index[0];
 70 | 		if (!(tc <= 57 && tc >= 48))
 71 | 			return [0];
 72 | 		str+=tc-48;
 73 | 		hash = crctable[index[0]] ^ (hash >>> 8);
 74 | 		return [1,str];
 75 | 	};
 76 | 	create_table();
 77 | 	var index=new Array(4);
 78 | 	console.log('初始化耗时：'+(performance.now()-startTime));
 79 | 	return function(input){
 80 | 		var ht=parseInt('0x'+input)^0xffffffff,
 81 | 		snum,i,lastindex,deepCheckData;
 82 | 		for(i=3;i>=0;i--){
 83 | 			index[3-i]=getcrcindex( ht >>> (i*8) );
 84 | 			snum=crctable[index[3-i]];
 85 | 			ht^=snum>>>((3-i)*8);
 86 | 		}
 87 | 		for(i=0;i<100000; i++){
 88 | 			lastindex = crc32lastindex(i);
 89 | 			if(lastindex == index[3]){
 90 | 				deepCheckData=deepCheck(i,index)
 91 | 				if(deepCheckData[0])
 92 | 					break;
 93 | 			}
 94 | 		}
 95 | 		if(i==100000)
 96 | 			return -1;
 97 | 		return i+''+deepCheckData[1];
 98 | 	}
 99 | }
100 | window.crc_engine=new BiliBili_midcrc();
101 | </script>


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