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var DEF_PAD_LENGTH = 16;
/**
* Append PKCS#7 padding to a buffer or a string.
*
* @see {@link http://tools.ietf.org/html/rfc5652|RFC 5652 section 6.3}
*
* @param {!(string|Uint8Array|Uint8ClampedArray)} data - the data to be padded
* @param {number=} size - the block size to pad for
* @return {!(string|Uint8Array|Uint8ClampedArray)} the padded data, if the function succeed
*/
function pad(data, size) {
var out = data;
if (typeof size !== 'number') {
size = DEF_PAD_LENGTH;
} else if (size > 255) {
throw new RangeError('pad(): PKCS#7 padding cannot be longer than 255 bytes');
} else if (size < 0) {
throw new RangeError('pad(): PKCS#7 padding size must be positive');
}
if (typeof data === 'string') {
var padLen = size - data.length % size;
if (isNaN(padLen)) padLen = 0;
var padChar = String.fromCharCode(padLen);
for (var i = 0; i < padLen; i++) {
out += padChar;
}
} else if (data instanceof Uint8Array || data instanceof Uint8ClampedArray) {
var baseLen = data.byteLength;
padLen = size - baseLen % size;
if (isNaN(padLen)) padLen = 0;
var newLen = baseLen + padLen;
out = new data.constructor(newLen);
out.set(data);
for (i = baseLen; i < newLen; i++) {
out[i] = padLen;
}
} else {
throw new TypeError('pad(): data could not be padded');
}
return out;
}
/**
* Remove the PKCS#7 padding from a buffer or a string.
*
* @see {@link http://tools.ietf.org/html/rfc5652|RFC 5652 section 6.3}
*
* @param {!(string|Uint8Array|Uint8ClampedArray)} data - the data to be unpadded
* @return {!(string|Uint8Array|Uint8ClampedArray)} the unpadded data, if the function succeed
*/
function unpad(data) {
var out = data;
if (typeof data === 'string' && data.length > 0) {
var padLen = data.charCodeAt(data.length - 1);
if (padLen > data.length) {
throw new Error('unpad(): cannot remove ' + padLen + ' bytes from a ' +
data.length + '-byte(s) string');
}
for (var i = data.length - 2, end = data.length - padLen; i >= end; i--) {
if (data.charCodeAt(i) !== padLen) {
throw new Error('unpad(): found a padding byte of ' + data.charCodeAt(i) +
' instead of ' + padLen + ' at position ' + i);
}
}
out = data.substring(0, end);
} else if (data instanceof Uint8Array || data instanceof Uint8ClampedArray) {
var baseLen = data.byteLength;
padLen = data[baseLen - 1];
var newLen = baseLen - padLen;
if (newLen < 0) {
throw new Error('unpad(): cannot remove ' + padLen + ' bytes from a ' +
baseLen + '-byte(s) string');
}
for (i = baseLen - 2; i >= newLen; i--) {
if (data[i] !== padLen) {
throw new Error('unpad(): found a padding byte of ' + data[i] +
' instead of ' + padLen + ' at position ' + i);
}
}
out = data.slice(0, newLen);
}
return out;
}
module.exports = { pad: pad, unpad: unpad };