mirror of
https://github.com/foliojs/pdfkit.git
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405 lines
12 KiB
JavaScript
405 lines
12 KiB
JavaScript
/*
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PDFSecurity - represents PDF security settings
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By Yang Liu <hi@zesik.com>
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*/
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import CryptoJS from 'crypto-js';
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import saslprep from 'saslprep';
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class PDFSecurity {
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static generateFileID(info = {}) {
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let infoStr = `${info.CreationDate.getTime()}\n`;
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for (let key in info) {
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if (!info.hasOwnProperty(key)) {
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continue;
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}
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infoStr += `${key}: ${info[key].toString()}\n`;
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}
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return wordArrayToBuffer(CryptoJS.MD5(infoStr));
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}
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static generateRandomWordArray(bytes) {
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return CryptoJS.lib.WordArray.random(bytes);
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}
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static create(document, options = {}) {
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if (!options.ownerPassword && !options.userPassword) {
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return null;
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}
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return new PDFSecurity(document, options);
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}
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constructor(document, options = {}) {
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if (!options.ownerPassword && !options.userPassword) {
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throw new Error('None of owner password and user password is defined.');
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}
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this.document = document;
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this._setupEncryption(options);
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}
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_setupEncryption(options) {
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switch (options.pdfVersion) {
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case '1.4':
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case '1.5':
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this.version = 2;
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break;
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case '1.6':
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case '1.7':
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this.version = 4;
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break;
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case '1.7ext3':
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this.version = 5;
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break;
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default:
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this.version = 1;
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break;
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}
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const encDict = {
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Filter: 'Standard'
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};
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switch (this.version) {
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case 1:
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case 2:
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case 4:
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this._setupEncryptionV1V2V4(this.version, encDict, options);
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break;
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case 5:
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this._setupEncryptionV5(encDict, options);
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break;
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}
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this.dictionary = this.document.ref(encDict);
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}
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_setupEncryptionV1V2V4(v, encDict, options) {
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let r, permissions;
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switch (v) {
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case 1:
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r = 2;
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this.keyBits = 40;
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permissions = getPermissionsR2(options.permissions);
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break;
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case 2:
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r = 3;
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this.keyBits = 128;
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permissions = getPermissionsR3(options.permissions);
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break;
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case 4:
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r = 4;
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this.keyBits = 128;
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permissions = getPermissionsR3(options.permissions);
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break;
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}
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const paddedUserPassword = processPasswordR2R3R4(options.userPassword);
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const paddedOwnerPassword = options.ownerPassword ?
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processPasswordR2R3R4(options.ownerPassword) : paddedUserPassword;
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const ownerPasswordEntry = getOwnerPasswordR2R3R4(r, this.keyBits, paddedUserPassword, paddedOwnerPassword);
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this.encryptionKey = getEncryptionKeyR2R3R4(r, this.keyBits, this.document._id,
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paddedUserPassword, ownerPasswordEntry, permissions);
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let userPasswordEntry;
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if (r === 2) {
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userPasswordEntry = getUserPasswordR2(this.encryptionKey);
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} else {
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userPasswordEntry = getUserPasswordR3R4(this.document._id, this.encryptionKey);
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}
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encDict.V = v;
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if (v >= 2) {
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encDict.Length = this.keyBits;
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}
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if (v === 4) {
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encDict.CF = {
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StdCF: {
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AuthEvent: 'DocOpen',
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CFM: 'AESV2',
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Length: this.keyBits / 8
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}
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};
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encDict.StmF = 'StdCF';
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encDict.StrF = 'StdCF';
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}
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encDict.R = r;
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encDict.O = wordArrayToBuffer(ownerPasswordEntry);
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encDict.U = wordArrayToBuffer(userPasswordEntry);
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encDict.P = permissions;
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}
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_setupEncryptionV5(encDict, options) {
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this.keyBits = 256;
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const permissions = getPermissionsR3(options);
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const processedUserPassword = processPasswordR5(options.userPassword);
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const processedOwnerPassword = options.ownerPassword ?
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processPasswordR5(options.ownerPassword) : processedUserPassword;
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this.encryptionKey = getEncryptionKeyR5(PDFSecurity.generateRandomWordArray);
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const userPasswordEntry = getUserPasswordR5(processedUserPassword, PDFSecurity.generateRandomWordArray);
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const userKeySalt = CryptoJS.lib.WordArray.create(userPasswordEntry.words.slice(10, 12), 8);
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const userEncryptionKeyEntry = getUserEncryptionKeyR5(processedUserPassword, userKeySalt, this.encryptionKey);
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const ownerPasswordEntry = getOwnerPasswordR5(processedOwnerPassword, userPasswordEntry,
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PDFSecurity.generateRandomWordArray);
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const ownerKeySalt = CryptoJS.lib.WordArray.create(ownerPasswordEntry.words.slice(10, 12), 8);
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const ownerEncryptionKeyEntry = getOwnerEncryptionKeyR5(processedOwnerPassword, ownerKeySalt, userPasswordEntry,
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this.encryptionKey);
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const permsEntry = getEncryptedPermissionsR5(permissions, this.encryptionKey, PDFSecurity.generateRandomWordArray);
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encDict.V = 5;
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encDict.Length = this.keyBits;
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encDict.CF = {
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StdCF: {
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AuthEvent: 'DocOpen',
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CFM: 'AESV3',
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Length: this.keyBits / 8
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}
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};
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encDict.StmF = 'StdCF';
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encDict.StrF = 'StdCF';
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encDict.R = 5;
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encDict.O = wordArrayToBuffer(ownerPasswordEntry);
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encDict.OE = wordArrayToBuffer(ownerEncryptionKeyEntry);
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encDict.U = wordArrayToBuffer(userPasswordEntry);
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encDict.UE = wordArrayToBuffer(userEncryptionKeyEntry);
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encDict.P = permissions;
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encDict.Perms = wordArrayToBuffer(permsEntry);
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}
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getEncryptFn(obj, gen) {
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let digest;
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if (this.version < 5) {
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digest = this.encryptionKey.clone().concat(CryptoJS.lib.WordArray.create([
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((obj & 0xff) << 24) | ((obj & 0xff00) << 8) | ((obj >> 8) & 0xff00) | (gen & 0xff), (gen & 0xff00) << 16
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], 5));
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}
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if (this.version === 1 || this.version === 2) {
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let key = CryptoJS.MD5(digest);
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key.sigBytes = Math.min(16, this.keyBits / 8 + 5);
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return buffer => wordArrayToBuffer(
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CryptoJS.RC4.encrypt(CryptoJS.lib.WordArray.create(buffer), key).ciphertext);
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}
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let key;
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if (this.version === 4) {
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key = CryptoJS.MD5(digest.concat(CryptoJS.lib.WordArray.create([0x73416c54], 4)));
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} else {
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key = this.encryptionKey;
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}
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const iv = PDFSecurity.generateRandomWordArray(16);
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const options = {
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mode: CryptoJS.mode.CBC,
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padding: CryptoJS.pad.Pkcs7,
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iv
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};
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return buffer => wordArrayToBuffer(
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iv.clone().concat(CryptoJS.AES.encrypt(CryptoJS.lib.WordArray.create(buffer), key, options).ciphertext));
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}
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end() {
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this.dictionary.end();
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}
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}
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function getPermissionsR2(permissionObject = {}) {
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let permissions = 0xffffffc0 >> 0;
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if (permissionObject.printing) {
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permissions |= 0b00000000010;
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}
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if (permissionObject.modifying) {
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permissions |= 0b000000001000;
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}
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if (permissionObject.copying) {
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permissions |= 0b000000010000;
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}
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if (permissionObject.annotating) {
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permissions |= 0b000000100000;
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}
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return permissions;
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}
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function getPermissionsR3(permissionObject = {}) {
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let permissions = 0xfffff0c0 >> 0;
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if (permissionObject.printing === 'lowResolution') {
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permissions |= 0b000000000100;
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}
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if (permissionObject.printing === 'highResolution') {
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permissions |= 0b100000000100;
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}
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if (permissionObject.modifying) {
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permissions |= 0b000000001000;
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}
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if (permissionObject.copying) {
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permissions |= 0b000000010000;
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}
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if (permissionObject.annotating) {
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permissions |= 0b000000100000;
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}
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if (permissionObject.fillingForms) {
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permissions |= 0b000100000000;
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}
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if (permissionObject.contentAccessibility) {
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permissions |= 0b001000000000;
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}
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if (permissionObject.documentAssembly) {
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permissions |= 0b010000000000;
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}
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return permissions;
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}
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function getUserPasswordR2(encryptionKey) {
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return CryptoJS.RC4.encrypt(processPasswordR2R3R4(), encryptionKey).ciphertext;
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}
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function getUserPasswordR3R4(documentId, encryptionKey) {
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const key = encryptionKey.clone();
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let cipher = CryptoJS.MD5(processPasswordR2R3R4().concat(CryptoJS.lib.WordArray.create(documentId)));
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for (let i = 0; i < 20; i++) {
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const xorRound = Math.ceil(key.sigBytes / 4);
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for (let j = 0; j < xorRound; j++) {
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key.words[j] = encryptionKey.words[j] ^ (i | (i << 8) | (i << 16) | (i << 24));
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}
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cipher = CryptoJS.RC4.encrypt(cipher, key).ciphertext;
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}
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return cipher.concat(CryptoJS.lib.WordArray.create(null, 16));
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}
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function getOwnerPasswordR2R3R4(r, keyBits, paddedUserPassword, paddedOwnerPassword) {
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let digest = paddedOwnerPassword;
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let round = r >= 3 ? 51 : 1;
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for (let i = 0; i < round; i++) {
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digest = CryptoJS.MD5(digest);
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}
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const key = digest.clone();
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key.sigBytes = keyBits / 8;
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let cipher = paddedUserPassword;
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round = r >= 3 ? 20 : 1;
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for (let i = 0; i < round; i++) {
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const xorRound = Math.ceil(key.sigBytes / 4);
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for (let j = 0; j < xorRound; j++) {
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key.words[j] = digest.words[j] ^ (i | (i << 8) | (i << 16) | (i << 24));
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}
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cipher = CryptoJS.RC4.encrypt(cipher, key).ciphertext;
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}
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return cipher;
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}
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function getEncryptionKeyR2R3R4(r, keyBits, documentId, paddedUserPassword, ownerPasswordEntry, permissions) {
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let key = paddedUserPassword.clone()
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.concat(ownerPasswordEntry)
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.concat(CryptoJS.lib.WordArray.create([lsbFirstWord(permissions)], 4))
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.concat(CryptoJS.lib.WordArray.create(documentId));
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const round = r >= 3 ? 51 : 1;
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for (let i = 0; i < round; i++) {
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key = CryptoJS.MD5(key);
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key.sigBytes = keyBits / 8;
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}
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return key;
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}
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function getUserPasswordR5(processedUserPassword, generateRandomWordArray) {
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const validationSalt = generateRandomWordArray(8);
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const keySalt = generateRandomWordArray(8);
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return CryptoJS.SHA256(processedUserPassword.clone().concat(validationSalt))
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.concat(validationSalt).concat(keySalt);
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}
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function getUserEncryptionKeyR5(processedUserPassword, userKeySalt, encryptionKey) {
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const key = CryptoJS.SHA256(processedUserPassword.clone().concat(userKeySalt));
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const options = {
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mode: CryptoJS.mode.CBC,
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padding: CryptoJS.pad.NoPadding,
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iv: CryptoJS.lib.WordArray.create(null, 16)
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};
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return CryptoJS.AES.encrypt(encryptionKey, key, options).ciphertext;
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}
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function getOwnerPasswordR5(processedOwnerPassword, userPasswordEntry, generateRandomWordArray) {
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const validationSalt = generateRandomWordArray(8);
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const keySalt = generateRandomWordArray(8);
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return CryptoJS.SHA256(processedOwnerPassword.clone().concat(validationSalt).concat(userPasswordEntry))
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.concat(validationSalt).concat(keySalt);
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}
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function getOwnerEncryptionKeyR5(processedOwnerPassword, ownerKeySalt, userPasswordEntry, encryptionKey) {
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const key = CryptoJS.SHA256(processedOwnerPassword.clone().concat(ownerKeySalt).concat(userPasswordEntry));
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const options = {
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mode: CryptoJS.mode.CBC,
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padding: CryptoJS.pad.NoPadding,
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iv: CryptoJS.lib.WordArray.create(null, 16)
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};
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return CryptoJS.AES.encrypt(encryptionKey, key, options).ciphertext;
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}
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function getEncryptionKeyR5(generateRandomWordArray) {
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return generateRandomWordArray(32);
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}
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function getEncryptedPermissionsR5(permissions, encryptionKey, generateRandomWordArray) {
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const cipher = CryptoJS.lib.WordArray.create([lsbFirstWord(permissions), 0xffffffff, 0x54616462], 12)
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.concat(generateRandomWordArray(4));
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const options = {
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mode: CryptoJS.mode.ECB,
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padding: CryptoJS.pad.NoPadding
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};
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return CryptoJS.AES.encrypt(cipher, encryptionKey, options).ciphertext;
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}
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function processPasswordR2R3R4(password = '') {
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const out = new Buffer(32);
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const length = password.length;
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let index = 0;
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while (index < length && index < 32) {
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const code = password.charCodeAt(index);
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if (code > 0xff) {
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throw new Error('Password contains one or more invalid characters.');
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}
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out[index] = code;
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index++;
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}
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while (index < 32) {
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out[index] = PASSWORD_PADDING[index - length];
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index++;
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}
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return CryptoJS.lib.WordArray.create(out);
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}
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function processPasswordR5(password = '') {
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password = unescape(encodeURIComponent(saslprep(password)));
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const length = Math.min(127, password.length);
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const out = new Buffer(length);
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for (let i = 0; i < length; i++) {
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out[i] = password.charCodeAt(i);
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}
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return CryptoJS.lib.WordArray.create(out);
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}
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function lsbFirstWord(data) {
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return ((data & 0xff) << 24) | ((data & 0xff00) << 8) | ((data >> 8) & 0xff00) | ((data >> 24) & 0xff);
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}
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function wordArrayToBuffer(wordArray) {
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const byteArray = [];
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for (let i = 0; i < wordArray.sigBytes; i++) {
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byteArray.push((wordArray.words[Math.floor(i / 4)] >> (8 * (3 - i % 4))) & 0xff);
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}
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return Buffer.from(byteArray);
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}
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const PASSWORD_PADDING = [
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0x28, 0xbf, 0x4e, 0x5e, 0x4e, 0x75, 0x8a, 0x41, 0x64, 0x00, 0x4e, 0x56, 0xff, 0xfa, 0x01, 0x08,
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0x2e, 0x2e, 0x00, 0xb6, 0xd0, 0x68, 0x3e, 0x80, 0x2f, 0x0c, 0xa9, 0xfe, 0x64, 0x53, 0x69, 0x7a
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];
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export default PDFSecurity;
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