base64加密和解密

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前端js加密

var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";  
  
function base64encode(str) {  
    var out, i, len;  
    var c1, c2, c3;  
    len = str.length;  
    i = 0;  
    out = "";  
    while(i < len) {  
        c1 = str.charCodeAt(i++) & 0xff;  
        if(i == len){  
           out += base64EncodeChars.charAt(c1 >> 2);  
           out += base64EncodeChars.charAt((c1 & 0x3) << 4);  
           out += "==";  
           break;  
        }  
        c2 = str.charCodeAt(i++);  
        if(i == len){  
           out += base64EncodeChars.charAt(c1 >> 2);  
           out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));  
           out += base64EncodeChars.charAt((c2 & 0xF) << 2);  
           out += "=";  
           break;  
        }  
        c3 = str.charCodeAt(i++);  
        out += base64EncodeChars.charAt(c1 >> 2);  
        out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4));  
        out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6));  
        out += base64EncodeChars.charAt(c3 & 0x3F);  
    }  
    return out;  
}

前端js解密

var base64DecodeChars = new Array(  
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,  
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,  
-1, 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, -1, -1, -1, -1, -1,  
-1, 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, -1, -1, -1, -1, -1);  

function base64decode(str) {  
    var c1, c2, c3, c4;  
    var i, len, out;  
    len = str.length;  
    i = 0;  
    out = "";  
    while(i < len) {  
        /* c1 */  
        do {  
          c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff];  
        }while(i < len && c1 == -1);  
        if(c1 == -1)  
        break;  

        /* c2 */  
        do {  
          c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff];  
        } while(i < len && c2 == -1);  
        if(c2 == -1)  
        break;  
        out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));  
        /* c3 */  
        do {  
          c3 = str.charCodeAt(i++) & 0xff;  
          if(c3 == 61)  
          return out;  
          c3 = base64DecodeChars[c3];  
        } while(i < len && c3 == -1);  
        if(c3 == -1)  
        break;  
        out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));  
        /* c4 */  
        do {  
          c4 = str.charCodeAt(i++) & 0xff;  
          if(c4 == 61)  
          return out;  
          c4 = base64DecodeChars[c4];  
        } while(i < len && c4 == -1);  
        if(c4 == -1)  
        break;  
        out += String.fromCharCode(((c3 & 0x03) << 6) | c4);  
    }  
    return out;  
}