57 lines
1.4 KiB
JavaScript
57 lines
1.4 KiB
JavaScript
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/** @fileOverview Bit array codec implementations.
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*
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* @author Emily Stark
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* @author Mike Hamburg
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* @author Dan Boneh
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*/
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/** @namespace Base64 encoding/decoding */
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sjcl.codec.base64 = {
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/** The base64 alphabet.
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* @private
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*/
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_chars: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
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/** Convert from a bitArray to a base64 string. */
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fromBits: function (arr, _noEquals) {
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var out = "", i, bits=0, c = sjcl.codec.base64._chars, ta=0, bl = sjcl.bitArray.bitLength(arr);
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for (i=0; out.length * 6 < bl; ) {
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out += c.charAt((ta ^ arr[i]>>>bits) >>> 26);
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if (bits < 6) {
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ta = arr[i] << (6-bits);
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bits += 26;
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i++;
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} else {
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ta <<= 6;
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bits -= 6;
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}
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}
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while ((out.length & 3) && !_noEquals) { out += "="; }
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return out;
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},
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/** Convert from a base64 string to a bitArray */
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toBits: function(str) {
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str = str.replace(/\s|=/g,'');
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var out = [], i, bits=0, c = sjcl.codec.base64._chars, ta=0, x;
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for (i=0; i<str.length; i++) {
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x = c.indexOf(str.charAt(i));
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if (x < 0) {
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throw new sjcl.exception.invalid("this isn't base64!");
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}
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if (bits > 26) {
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bits -= 26;
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out.push(ta ^ x>>>bits);
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ta = x << (32-bits);
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} else {
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bits += 6;
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ta ^= x << (32-bits);
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}
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}
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if (bits&56) {
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out.push(sjcl.bitArray.partial(bits&56, ta, 1));
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}
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return out;
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}
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};
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