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Inline the concatArrays function in calculatePDF20Hash

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This helper function is first of all only called *twice*, and secondly it also leads to unnecessary intermediate allocations given how the `TypedArray`s are handled.
Hence we can simply inline this small function, and thus directly allocate the combined `TypedArray` instead.
This commit is contained in:
Jonas Jenwald 2021-02-26 15:51:39 +01:00
parent 9a9a5b2365
commit b884757873
1 changed files with 11 additions and 13 deletions
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24
src/core/crypto.js
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@ -1323,26 +1323,24 @@ var PDF17 = (function PDF17Closure() {
})(); })();
var PDF20 = (function PDF20Closure() { var PDF20 = (function PDF20Closure() {
function concatArrays(array1, array2) {
var t = new Uint8Array(array1.length + array2.length);
t.set(array1, 0);
t.set(array2, array1.length);
return t;
}
function calculatePDF20Hash(password, input, userBytes) { function calculatePDF20Hash(password, input, userBytes) {
// This refers to Algorithm 2.B as defined in ISO 32000-2. // This refers to Algorithm 2.B as defined in ISO 32000-2.
var k = calculateSHA256(input, 0, input.length).subarray(0, 32); var k = calculateSHA256(input, 0, input.length).subarray(0, 32);
var e = [0]; var e = [0];
var i = 0; var i = 0;
while (i < 64 || e[e.length - 1] > i - 32) { while (i < 64 || e[e.length - 1] > i - 32) {
var arrayLength = password.length + k.length + userBytes.length; const combinedLength = password.length + k.length + userBytes.length,
combinedArray = new Uint8Array(combinedLength);
let writeOffset = 0;
combinedArray.set(password, writeOffset);
writeOffset += password.length;
combinedArray.set(k, writeOffset);
writeOffset += k.length;
combinedArray.set(userBytes, writeOffset);
var k1 = new Uint8Array(arrayLength * 64); var k1 = new Uint8Array(combinedLength * 64);
var array = concatArrays(password, k); for (var j = 0, pos = 0; j < 64; j++, pos += combinedLength) {
array = concatArrays(array, userBytes); k1.set(combinedArray, pos);
for (var j = 0, pos = 0; j < 64; j++, pos += arrayLength) {
k1.set(array, pos);
} }
// AES128 CBC NO PADDING with first 16 bytes of k as the key // AES128 CBC NO PADDING with first 16 bytes of k as the key
// and the second 16 as the iv. // and the second 16 as the iv.