js base64加解密

2023-10-02 14 0

/*

* 加密解密

* */

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;

}

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