From 5e0722e4c262c13921176aa5f33df4b14d364595 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sun, 23 Apr 2023 10:08:17 +0200
Subject: [PATCH 1/2] Remove the `PDF20` closure, in the `src/core/crypto.js`
 file

To allow doing this the existing helper function was changed into a "private" method instead.
---
 src/core/crypto.js | 92 +++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 51 deletions(-)

diff --git a/src/core/crypto.js b/src/core/crypto.js
index 22bf8aac1..0cd5b7ade 100644
--- a/src/core/crypto.js
+++ b/src/core/crypto.js
@@ -1278,8 +1278,8 @@ class PDF17 {
   }
 }
 
-const PDF20 = (function PDF20Closure() {
-  function calculatePDF20Hash(password, input, userBytes) {
+class PDF20 {
+  _hash(password, input, userBytes) {
     // This refers to Algorithm 2.B as defined in ISO 32000-2.
     let k = calculateSHA256(input, 0, input.length).subarray(0, 32);
     let e = [0];
@@ -1321,57 +1321,47 @@ const PDF20 = (function PDF20Closure() {
     return k.subarray(0, 32);
   }
 
-  // eslint-disable-next-line no-shadow
-  class PDF20 {
-    hash(password, concatBytes, userBytes) {
-      return calculatePDF20Hash(password, concatBytes, userBytes);
-    }
-
-    checkOwnerPassword(
-      password,
-      ownerValidationSalt,
-      userBytes,
-      ownerPassword
-    ) {
-      const hashData = new Uint8Array(password.length + 56);
-      hashData.set(password, 0);
-      hashData.set(ownerValidationSalt, password.length);
-      hashData.set(userBytes, password.length + ownerValidationSalt.length);
-      const result = calculatePDF20Hash(password, hashData, userBytes);
-      return isArrayEqual(result, ownerPassword);
-    }
-
-    checkUserPassword(password, userValidationSalt, userPassword) {
-      const hashData = new Uint8Array(password.length + 8);
-      hashData.set(password, 0);
-      hashData.set(userValidationSalt, password.length);
-      const result = calculatePDF20Hash(password, hashData, []);
-      return isArrayEqual(result, userPassword);
-    }
-
-    getOwnerKey(password, ownerKeySalt, userBytes, ownerEncryption) {
-      const hashData = new Uint8Array(password.length + 56);
-      hashData.set(password, 0);
-      hashData.set(ownerKeySalt, password.length);
-      hashData.set(userBytes, password.length + ownerKeySalt.length);
-      const key = calculatePDF20Hash(password, hashData, userBytes);
-      const cipher = new AES256Cipher(key);
-      return cipher.decryptBlock(ownerEncryption, false, new Uint8Array(16));
-    }
-
-    getUserKey(password, userKeySalt, userEncryption) {
-      const hashData = new Uint8Array(password.length + 8);
-      hashData.set(password, 0);
-      hashData.set(userKeySalt, password.length);
-      // `key` is the decryption key for the UE string.
-      const key = calculatePDF20Hash(password, hashData, []);
-      const cipher = new AES256Cipher(key);
-      return cipher.decryptBlock(userEncryption, false, new Uint8Array(16));
-    }
+  hash(password, concatBytes, userBytes) {
+    return this._hash(password, concatBytes, userBytes);
   }
 
-  return PDF20;
-})();
+  checkOwnerPassword(password, ownerValidationSalt, userBytes, ownerPassword) {
+    const hashData = new Uint8Array(password.length + 56);
+    hashData.set(password, 0);
+    hashData.set(ownerValidationSalt, password.length);
+    hashData.set(userBytes, password.length + ownerValidationSalt.length);
+    const result = this._hash(password, hashData, userBytes);
+    return isArrayEqual(result, ownerPassword);
+  }
+
+  checkUserPassword(password, userValidationSalt, userPassword) {
+    const hashData = new Uint8Array(password.length + 8);
+    hashData.set(password, 0);
+    hashData.set(userValidationSalt, password.length);
+    const result = this._hash(password, hashData, []);
+    return isArrayEqual(result, userPassword);
+  }
+
+  getOwnerKey(password, ownerKeySalt, userBytes, ownerEncryption) {
+    const hashData = new Uint8Array(password.length + 56);
+    hashData.set(password, 0);
+    hashData.set(ownerKeySalt, password.length);
+    hashData.set(userBytes, password.length + ownerKeySalt.length);
+    const key = this._hash(password, hashData, userBytes);
+    const cipher = new AES256Cipher(key);
+    return cipher.decryptBlock(ownerEncryption, false, new Uint8Array(16));
+  }
+
+  getUserKey(password, userKeySalt, userEncryption) {
+    const hashData = new Uint8Array(password.length + 8);
+    hashData.set(password, 0);
+    hashData.set(userKeySalt, password.length);
+    // `key` is the decryption key for the UE string.
+    const key = this._hash(password, hashData, []);
+    const cipher = new AES256Cipher(key);
+    return cipher.decryptBlock(userEncryption, false, new Uint8Array(16));
+  }
+}
 
 class CipherTransform {
   constructor(stringCipherConstructor, streamCipherConstructor) {

From 74585c7c59df39cdea39c5440b2f318fe0579d7f Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sun, 23 Apr 2023 10:13:46 +0200
Subject: [PATCH 2/2] Remove the unused `PDF20.hash` method

This method was added in PR 4938, almost nine years ago, however it doesn't appear to ever have been used.
Given the similarities between the `PDF17` and `PDF20` classes, and how they're used, if the `PDF20.hash` method was actually necessary you'd also expect a similiar method in the `PDF17` class.
---
 src/core/crypto.js | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/src/core/crypto.js b/src/core/crypto.js
index 0cd5b7ade..c8e6f2bc9 100644
--- a/src/core/crypto.js
+++ b/src/core/crypto.js
@@ -1321,10 +1321,6 @@ class PDF20 {
     return k.subarray(0, 32);
   }
 
-  hash(password, concatBytes, userBytes) {
-    return this._hash(password, concatBytes, userBytes);
-  }
-
   checkOwnerPassword(password, ownerValidationSalt, userBytes, ownerPassword) {
     const hashData = new Uint8Array(password.length + 56);
     hashData.set(password, 0);