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base64 javascript 加密解密

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<HTML> 

<HEAD> 

<TITLE>Base64-www.51windows.Net</TITLE> 

<script language=javascript> 

var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 

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 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; 

}

 

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; 

}

 

function utf16to8(str) { 

var out, i, len, c;

 

out = ""; 

len = str.length; 

for(i = 0; i < len; i++) { 

c = str.charCodeAt(i); 

if ((c >= 0x0001) && (c <= 0x007F)) { 

out += str.charAt(i); 

} else if (c > 0x07FF) { 

out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F)); 

out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F)); 

out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); 

} else { 

out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F)); 

out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); 

return out; 

}

 

function utf8to16(str) { 

var out, i, len, c; 

var char2, char3;

 

out = ""; 

len = str.length; 

i = 0; 

while(i < len) { 

c = str.charCodeAt(i++); 

switch(c >> 4) 

case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: 

// 0xxxxxxx 

out += str.charAt(i-1); 

break; 

case 12: case 13: 

// 110x xxxx 10xx xxxx 

char2 = str.charCodeAt(i++); 

out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F)); 

break; 

case 14: 

// 1110 xxxx 10xx xxxx 10xx xxxx 

char2 = str.charCodeAt(i++); 

char3 = str.charCodeAt(i++); 

out += String.fromCharCode(((c & 0x0F) << 12) | 

((char2 & 0x3F) << 6) | 

((char3 & 0x3F) << 0)); 

break; 

}

 

return out; 

}

 

 

function doit() { 

  var f = document.f 

  f.output.value = base64encode(utf16to8(f.source.value)) 

  f.decode.value = utf8to16(base64decode(f.output.value)) 

</script> 

 

</HEAD> 

<BODY> 

<H1>Base64</H1> 

<FORM NAME="f"> 

原码<BR> 

<TEXTAREA NAME="source" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR> 

  Base64 encode<BR> 

<TEXTAREA NAME="output" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR> 

  Base64 decode<BR> 

<TEXTAREA NAME="decode" ROWS=4 COLS=60 WRAP="soft"></TEXTAREA><BR><BR> 

<INPUT TYPE=BUTTON VALUE="转换" ONCLICK="doit()"> 

</FORM> 

</BODY> 

<div style="position: absolute; top: 10; right: 10; width: 148; height: 18;cursor:hand"> 

<input type="button" name="Button" value="查看源代码" onClick= 'window.location = "view-source:" + window.location.href'></div>

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