| /* ==================================================================== |
| Licensed to the Apache Software Foundation (ASF) under one or more |
| contributor license agreements. See the NOTICE file distributed with |
| this work for additional information regarding copyright ownership. |
| The ASF licenses this file to You under the Apache License, Version 2.0 |
| (the "License"); you may not use this file except in compliance with |
| the License. You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, software |
| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| See the License for the specific language governing permissions and |
| limitations under the License. |
| ==================================================================== */ |
| package org.apache.poi.poifs.crypt; |
| |
| import java.nio.charset.StandardCharsets; |
| import java.security.DigestException; |
| import java.security.GeneralSecurityException; |
| import java.security.Key; |
| import java.security.MessageDigest; |
| import java.security.Provider; |
| import java.security.Security; |
| import java.security.spec.AlgorithmParameterSpec; |
| import java.util.Arrays; |
| import java.util.Locale; |
| |
| import javax.crypto.Cipher; |
| import javax.crypto.Mac; |
| import javax.crypto.SecretKey; |
| import javax.crypto.spec.IvParameterSpec; |
| import javax.crypto.spec.RC2ParameterSpec; |
| |
| import org.apache.poi.EncryptedDocumentException; |
| import org.apache.poi.util.IOUtils; |
| import org.apache.poi.util.Internal; |
| import org.apache.poi.util.LittleEndian; |
| import org.apache.poi.util.LittleEndianConsts; |
| import org.apache.poi.util.StringUtil; |
| |
| /** |
| * Helper functions used for standard and agile encryption |
| */ |
| @Internal |
| public final class CryptoFunctions { |
| |
| //arbitrarily selected; may need to increase |
| private static final int MAX_RECORD_LENGTH = 100_000; |
| |
| private CryptoFunctions() { |
| } |
| |
| /** |
| * <p><cite>2.3.4.7 ECMA-376 Document Encryption Key Generation (Standard Encryption)<br> |
| * 2.3.4.11 Encryption Key Generation (Agile Encryption)</cite></p> |
| * |
| * <p>The encryption key for ECMA-376 document encryption [ECMA-376] using agile |
| * encryption MUST be generated by using the following method, which is derived from PKCS #5: |
| * <a href="https://www.ietf.org/rfc/rfc2898.txt">Password-Based Cryptography Version 2.0 [RFC2898]</a>.</p> |
| * |
| * <p>Let H() be a hashing algorithm as determined by the PasswordKeyEncryptor.hashAlgorithm |
| * element, H_n be the hash data of the n-th iteration, and a plus sign (+) represent concatenation. |
| * The password MUST be provided as an array of Unicode characters. Limitations on the length of the |
| * password and the characters used by the password are implementation-dependent. |
| * The initial password hash is generated as follows:</p> |
| * |
| * |
| * <pre>H_0 = H(salt + password)</pre> |
| * |
| * <p>The salt used MUST be generated randomly. The salt MUST be stored in the |
| * PasswordKeyEncryptor.saltValue element contained within the \EncryptionInfo stream as |
| * specified in section 2.3.4.10. The hash is then iterated by using the following approach:</p> |
| * |
| * <pre>H_n = H(iterator + H_n-1)</pre> |
| * |
| * <p>where iterator is an unsigned 32-bit value that is initially set to 0x00000000 and then incremented |
| * monotonically on each iteration until PasswordKey.spinCount iterations have been performed. |
| * The value of iterator on the last iteration MUST be one less than PasswordKey.spinCount.</p> |
| * |
| * <p>For POI, H_final will be calculated by {@link #generateKey(byte[],HashAlgorithm,byte[],int)}</p> |
| * |
| * @param password the password |
| * @param hashAlgorithm the hash algorithm |
| * @param salt the initial salt value |
| * @param spinCount the repetition count |
| * @return the hashed password |
| */ |
| public static byte[] hashPassword(String password, HashAlgorithm hashAlgorithm, byte[] salt, int spinCount) { |
| return hashPassword(password, hashAlgorithm, salt, spinCount, true); |
| } |
| |
| /** |
| * Generalized method for read and write protection hash generation. |
| * The difference is, read protection uses the order iterator then hash in the hash loop, whereas write protection |
| * uses first the last hash value and then the current iterator value |
| * |
| * @param password the pasword |
| * @param hashAlgorithm the hash algorighm |
| * @param salt the initial salt value |
| * @param spinCount the repetition count |
| * @param iteratorFirst if true, the iterator is hashed before the n-1 hash value, |
| * if false the n-1 hash value is applied first |
| * @return the hashed password |
| */ |
| @SuppressWarnings({"squid:S2068"}) |
| public static byte[] hashPassword(String password, HashAlgorithm hashAlgorithm, byte[] salt, int spinCount, boolean iteratorFirst) { |
| // If no password was given, use the default |
| if (password == null) { |
| password = Decryptor.DEFAULT_PASSWORD; |
| } |
| |
| MessageDigest hashAlg = getMessageDigest(hashAlgorithm); |
| |
| hashAlg.update(salt); |
| byte[] hash = hashAlg.digest(StringUtil.getToUnicodeLE(password)); |
| byte[] iterator = new byte[LittleEndianConsts.INT_SIZE]; |
| |
| byte[] first = (iteratorFirst ? iterator : hash); |
| byte[] second = (iteratorFirst ? hash : iterator); |
| |
| try { |
| for (int i = 0; i < spinCount; i++) { |
| LittleEndian.putInt(iterator, 0, i); |
| hashAlg.reset(); |
| hashAlg.update(first); |
| hashAlg.update(second); |
| hashAlg.digest(hash, 0, hash.length); // don't create hash buffer everytime new |
| } |
| } catch (DigestException e) { |
| throw new EncryptedDocumentException("error in password hashing"); |
| } |
| |
| return hash; |
| } |
| |
| /** |
| * <p><cite>2.3.4.12 Initialization Vector Generation (Agile Encryption)</cite></p> |
| * |
| * <p>Initialization vectors are used in all cases for agile encryption. An initialization vector MUST be |
| * generated by using the following method, where H() is a hash function that MUST be the same as |
| * specified in section 2.3.4.11 and a plus sign (+) represents concatenation:</p> |
| * <ul> |
| * <li>If a blockKey is provided, let IV be a hash of the KeySalt and the following value:<br> |
| * {@code blockKey: IV = H(KeySalt + blockKey)}</li> |
| * <li>If a blockKey is not provided, let IV be equal to the following value:<br> |
| * {@code KeySalt:IV = KeySalt}</li> |
| * <li>If the number of bytes in the value of IV is less than the the value of the blockSize attribute |
| * corresponding to the cipherAlgorithm attribute, pad the array of bytes by appending 0x36 until |
| * the array is blockSize bytes. If the array of bytes is larger than blockSize bytes, truncate the |
| * array to blockSize bytes.</li> |
| * </ul> |
| **/ |
| public static byte[] generateIv(HashAlgorithm hashAlgorithm, byte[] salt, byte[] blockKey, int blockSize) { |
| byte[] iv = salt; |
| if (blockKey != null) { |
| MessageDigest hashAlgo = getMessageDigest(hashAlgorithm); |
| hashAlgo.update(salt); |
| iv = hashAlgo.digest(blockKey); |
| } |
| return getBlock36(iv, blockSize); |
| } |
| |
| /** |
| * <p><cite>2.3.4.11 Encryption Key Generation (Agile Encryption)</cite></p> |
| * |
| * <p>The final hash data that is used for an encryption key is then generated by using the following |
| * method:</p> |
| * |
| * <pre>H_final = H(H_n + blockKey)</pre> |
| * |
| * <p>where blockKey represents an array of bytes used to prevent two different blocks from encrypting |
| * to the same cipher text.</p> |
| * |
| * <p>If the size of the resulting H_final is smaller than that of PasswordKeyEncryptor.keyBits, the key |
| * MUST be padded by appending bytes with a value of 0x36. If the hash value is larger in size than |
| * PasswordKeyEncryptor.keyBits, the key is obtained by truncating the hash value.</p> |
| * |
| * @param passwordHash the hashed password byte |
| * @param hashAlgorithm the hash algorithm |
| * @param blockKey the block key |
| * @param keySize the key size |
| * @return intermediate key |
| */ |
| public static byte[] generateKey(byte[] passwordHash, HashAlgorithm hashAlgorithm, byte[] blockKey, int keySize) { |
| MessageDigest hashAlgo = getMessageDigest(hashAlgorithm); |
| hashAlgo.update(passwordHash); |
| byte[] key = hashAlgo.digest(blockKey); |
| return getBlock36(key, keySize); |
| } |
| |
| /** |
| * Initialize a new cipher object with the given cipher properties and no padding |
| * If the given algorithm is not implemented in the JCE, it will try to load it from the bouncy castle |
| * provider. |
| * |
| * @param key the secret key |
| * @param cipherAlgorithm the cipher algorithm |
| * @param chain the chaining mode |
| * @param vec the initialization vector (IV), can be null |
| * @param cipherMode Cipher.DECRYPT_MODE or Cipher.ENCRYPT_MODE |
| * @return the requested cipher |
| * @throws EncryptedDocumentException if the initialization failed or if an algorithm was specified, |
| * which depends on a missing bouncy castle provider |
| */ |
| public static Cipher getCipher(SecretKey key, CipherAlgorithm cipherAlgorithm, ChainingMode chain, byte[] vec, int cipherMode) { |
| return getCipher(key, cipherAlgorithm, chain, vec, cipherMode, null); |
| } |
| |
| /** |
| * Initialize a new cipher object with the given cipher properties |
| * If the given algorithm is not implemented in the JCE, it will try to load it from the bouncy castle |
| * provider. |
| * |
| * @param key the secret key |
| * @param cipherAlgorithm the cipher algorithm |
| * @param chain the chaining mode |
| * @param vec the initialization vector (IV), can be null |
| * @param cipherMode Cipher.DECRYPT_MODE or Cipher.ENCRYPT_MODE |
| * @param padding the padding (null = NOPADDING, ANSIX923Padding, PKCS5Padding, PKCS7Padding, ISO10126Padding, ...) |
| * @return the requested cipher |
| * @throws EncryptedDocumentException if the initialization failed or if an algorithm was specified, |
| * which depends on a missing bouncy castle provider |
| */ |
| public static Cipher getCipher(Key key, CipherAlgorithm cipherAlgorithm, ChainingMode chain, byte[] vec, int cipherMode, String padding) { |
| int keySizeInBytes = key.getEncoded().length; |
| if (padding == null) padding = "NoPadding"; |
| |
| try { |
| // Ensure the JCE policies files allow for this sized key |
| if (Cipher.getMaxAllowedKeyLength(cipherAlgorithm.jceId) < keySizeInBytes*8) { |
| throw new EncryptedDocumentException("Export Restrictions in place - please install JCE Unlimited Strength Jurisdiction Policy files"); |
| } |
| |
| Cipher cipher; |
| if (cipherAlgorithm == CipherAlgorithm.rc4) { |
| cipher = Cipher.getInstance(cipherAlgorithm.jceId); |
| } else if (cipherAlgorithm.needsBouncyCastle) { |
| registerBouncyCastle(); |
| cipher = Cipher.getInstance(cipherAlgorithm.jceId + "/" + chain.jceId + "/" + padding, "BC"); |
| } else { |
| cipher = Cipher.getInstance(cipherAlgorithm.jceId + "/" + chain.jceId + "/" + padding); |
| } |
| |
| if (vec == null) { |
| cipher.init(cipherMode, key); |
| } else { |
| AlgorithmParameterSpec aps; |
| if (cipherAlgorithm == CipherAlgorithm.rc2) { |
| aps = new RC2ParameterSpec(key.getEncoded().length*8, vec); |
| } else { |
| aps = new IvParameterSpec(vec); |
| } |
| cipher.init(cipherMode, key, aps); |
| } |
| return cipher; |
| } catch (GeneralSecurityException e) { |
| throw new EncryptedDocumentException(e); |
| } |
| } |
| |
| /** |
| * Returns a new byte array with a truncated to the given size. |
| * If the hash has less then size bytes, it will be filled with 0x36-bytes |
| * |
| * @param hash the to be truncated/filled hash byte array |
| * @param size the size of the returned byte array |
| * @return the padded hash |
| */ |
| private static byte[] getBlock36(byte[] hash, int size) { |
| return getBlockX(hash, size, (byte)0x36); |
| } |
| |
| /** |
| * Returns a new byte array with a truncated to the given size. |
| * If the hash has less then size bytes, it will be filled with 0-bytes |
| * |
| * @param hash the to be truncated/filled hash byte array |
| * @param size the size of the returned byte array |
| * @return the padded hash |
| */ |
| public static byte[] getBlock0(byte[] hash, int size) { |
| return getBlockX(hash, size, (byte)0); |
| } |
| |
| private static byte[] getBlockX(byte[] hash, int size, byte fill) { |
| if (hash.length == size) return hash; |
| |
| byte[] result = IOUtils.safelyAllocate(size, MAX_RECORD_LENGTH); |
| Arrays.fill(result, fill); |
| System.arraycopy(hash, 0, result, 0, Math.min(result.length, hash.length)); |
| return result; |
| } |
| |
| public static MessageDigest getMessageDigest(HashAlgorithm hashAlgorithm) { |
| try { |
| if (hashAlgorithm.needsBouncyCastle) { |
| registerBouncyCastle(); |
| return MessageDigest.getInstance(hashAlgorithm.jceId, "BC"); |
| } else { |
| return MessageDigest.getInstance(hashAlgorithm.jceId); |
| } |
| } catch (GeneralSecurityException e) { |
| throw new EncryptedDocumentException("hash algo not supported", e); |
| } |
| } |
| |
| public static Mac getMac(HashAlgorithm hashAlgorithm) { |
| try { |
| if (hashAlgorithm.needsBouncyCastle) { |
| registerBouncyCastle(); |
| return Mac.getInstance(hashAlgorithm.jceHmacId, "BC"); |
| } else { |
| return Mac.getInstance(hashAlgorithm.jceHmacId); |
| } |
| } catch (GeneralSecurityException e) { |
| throw new EncryptedDocumentException("hmac algo not supported", e); |
| } |
| } |
| |
| @SuppressWarnings("unchecked") |
| public static void registerBouncyCastle() { |
| if (Security.getProvider("BC") != null) { |
| return; |
| } |
| |
| try { |
| ClassLoader cl = CryptoFunctions.class.getClassLoader(); |
| String bcProviderName = "org.bouncycastle.jce.provider.BouncyCastleProvider"; |
| Class<Provider> clazz = (Class<Provider>)cl.loadClass(bcProviderName); |
| Security.addProvider(clazz.getDeclaredConstructor().newInstance()); |
| } catch (Exception e) { |
| throw new EncryptedDocumentException("Only the BouncyCastle provider supports your encryption settings - please add it to the classpath.", e); |
| } |
| } |
| |
| private static final int[] INITIAL_CODE_ARRAY = { |
| 0xE1F0, 0x1D0F, 0xCC9C, 0x84C0, 0x110C, 0x0E10, 0xF1CE, |
| 0x313E, 0x1872, 0xE139, 0xD40F, 0x84F9, 0x280C, 0xA96A, |
| 0x4EC3 |
| }; |
| |
| private static final byte[] PAD_ARRAY = { |
| (byte) 0xBB, (byte) 0xFF, (byte) 0xFF, (byte) 0xBA, (byte) 0xFF, |
| (byte) 0xFF, (byte) 0xB9, (byte) 0x80, (byte) 0x00, (byte) 0xBE, |
| (byte) 0x0F, (byte) 0x00, (byte) 0xBF, (byte) 0x0F, (byte) 0x00 |
| }; |
| |
| private static final int[][] ENCRYPTION_MATRIX = { |
| /* char 1 */ {0xAEFC, 0x4DD9, 0x9BB2, 0x2745, 0x4E8A, 0x9D14, 0x2A09}, |
| /* char 2 */ {0x7B61, 0xF6C2, 0xFDA5, 0xEB6B, 0xC6F7, 0x9DCF, 0x2BBF}, |
| /* char 3 */ {0x4563, 0x8AC6, 0x05AD, 0x0B5A, 0x16B4, 0x2D68, 0x5AD0}, |
| /* char 4 */ {0x0375, 0x06EA, 0x0DD4, 0x1BA8, 0x3750, 0x6EA0, 0xDD40}, |
| /* char 5 */ {0xD849, 0xA0B3, 0x5147, 0xA28E, 0x553D, 0xAA7A, 0x44D5}, |
| /* char 6 */ {0x6F45, 0xDE8A, 0xAD35, 0x4A4B, 0x9496, 0x390D, 0x721A}, |
| /* char 7 */ {0xEB23, 0xC667, 0x9CEF, 0x29FF, 0x53FE, 0xA7FC, 0x5FD9}, |
| /* char 8 */ {0x47D3, 0x8FA6, 0x0F6D, 0x1EDA, 0x3DB4, 0x7B68, 0xF6D0}, |
| /* char 9 */ {0xB861, 0x60E3, 0xC1C6, 0x93AD, 0x377B, 0x6EF6, 0xDDEC}, |
| /* char 10 */ {0x45A0, 0x8B40, 0x06A1, 0x0D42, 0x1A84, 0x3508, 0x6A10}, |
| /* char 11 */ {0xAA51, 0x4483, 0x8906, 0x022D, 0x045A, 0x08B4, 0x1168}, |
| /* char 12 */ {0x76B4, 0xED68, 0xCAF1, 0x85C3, 0x1BA7, 0x374E, 0x6E9C}, |
| /* char 13 */ {0x3730, 0x6E60, 0xDCC0, 0xA9A1, 0x4363, 0x86C6, 0x1DAD}, |
| /* char 14 */ {0x3331, 0x6662, 0xCCC4, 0x89A9, 0x0373, 0x06E6, 0x0DCC}, |
| /* char 15 */ {0x1021, 0x2042, 0x4084, 0x8108, 0x1231, 0x2462, 0x48C4} |
| }; |
| |
| /** |
| * Create the verifier for xor obfuscation (method 1) |
| * |
| * @see <a href="http://msdn.microsoft.com/en-us/library/dd926947.aspx">2.3.7.1 Binary Document Password Verifier Derivation Method 1</a> |
| * @see <a href="http://msdn.microsoft.com/en-us/library/dd905229.aspx">2.3.7.4 Binary Document Password Verifier Derivation Method 2</a> |
| * @see <a href="http://www.ecma-international.org/news/TC45_current_work/Office Open XML Part 4 - Markup Language Reference.pdf">Part 4 - Markup Language Reference - Ecma International - 3.2.12 fileSharing</a> |
| * |
| * @param password the password |
| * @return the verifier (actually a short value) |
| */ |
| public static int createXorVerifier1(String password) { |
| if (password == null) { |
| throw new IllegalArgumentException("Password cannot be null"); |
| } |
| |
| byte[] arrByteChars = toAnsiPassword(password); |
| |
| // SET Verifier TO 0x0000 |
| short verifier = 0; |
| |
| if (!password.isEmpty()) { |
| // FOR EACH PasswordByte IN PasswordArray IN REVERSE ORDER |
| for (int i = arrByteChars.length-1; i >= 0; i--) { |
| // SET Verifier TO Intermediate3 BITWISE XOR PasswordByte |
| verifier = rotateLeftBase15Bit(verifier); |
| verifier ^= arrByteChars[i]; |
| } |
| |
| // as we haven't prepended the password length into the input array |
| // we need to do it now separately ... |
| verifier = rotateLeftBase15Bit(verifier); |
| verifier ^= arrByteChars.length; |
| |
| // RETURN Verifier BITWISE XOR 0xCE4B |
| verifier ^= 0xCE4B; // (0x8000 | ('N' << 8) | 'K') |
| } |
| |
| return verifier & 0xFFFF; |
| } |
| |
| /** |
| * This method generates the xor verifier for word documents < 2007 (method 2). |
| * Its output will be used as password input for the newer word generations which |
| * utilize a real hashing algorithm like sha1. |
| * |
| * @param password the password |
| * @return the hashed password |
| * |
| * @see <a href="http://msdn.microsoft.com/en-us/library/dd905229.aspx">2.3.7.4 Binary Document Password Verifier Derivation Method 2</a> |
| * @see <a href="http://blogs.msdn.com/b/vsod/archive/2010/04/05/how-to-set-the-editing-restrictions-in-word-using-open-xml-sdk-2-0.aspx">How to set the editing restrictions in Word using Open XML SDK 2.0</a> |
| * @see <a href="http://www.aspose.com/blogs/aspose-blogs/vladimir-averkin/archive/2007/08/20/funny-how-the-new-powerful-cryptography-implemented-in-word-2007-turns-it-into-a-perfect-tool-for-document-password-removal.html">Funny: How the new powerful cryptography implemented in Word 2007 turns it into a perfect tool for document password removal.</a> |
| */ |
| public static int createXorVerifier2(String password) { |
| if (password == null) { |
| throw new IllegalArgumentException("Password cannot be null"); |
| } |
| |
| //Array to hold Key Values |
| byte[] generatedKey = new byte[4]; |
| |
| //Maximum length of the password is 15 chars. |
| final int maxPasswordLength = 15; |
| |
| if (!password.isEmpty()) { |
| // Truncate the password to 15 characters |
| password = password.substring(0, Math.min(password.length(), maxPasswordLength)); |
| |
| byte[] arrByteChars = toAnsiPassword(password); |
| |
| // Compute the high-order word of the new key: |
| |
| // --> Initialize from the initial code array (see below), depending on the passwords length. |
| int highOrderWord = INITIAL_CODE_ARRAY[arrByteChars.length - 1]; |
| |
| // --> For each character in the password: |
| // --> For every bit in the character, starting with the least significant and progressing to (but excluding) |
| // the most significant, if the bit is set, XOR the keys high-order word with the corresponding word from |
| // the Encryption Matrix |
| int line = maxPasswordLength - arrByteChars.length; |
| for (byte ch : arrByteChars) { |
| for (int xor : ENCRYPTION_MATRIX[line++]) { |
| if ((ch & 1) == 1) { |
| highOrderWord ^= xor; |
| } |
| ch >>>= 1; |
| } |
| } |
| |
| // Compute the low-order word of the new key: |
| int verifier = createXorVerifier1(password); |
| |
| // The byte order of the result shall be reversed [password "Example": 0x64CEED7E becomes 7EEDCE64], |
| // and that value shall be hashed as defined by the attribute values. |
| |
| LittleEndian.putShort(generatedKey, 0, (short)verifier); |
| LittleEndian.putShort(generatedKey, 2, (short)highOrderWord); |
| } |
| |
| return LittleEndian.getInt(generatedKey); |
| } |
| |
| /** |
| * This method generates the xored-hashed password for word documents < 2007. |
| */ |
| public static String xorHashPassword(String password) { |
| int hashedPassword = createXorVerifier2(password); |
| return String.format(Locale.ROOT, "%1$08X", hashedPassword); |
| } |
| |
| /** |
| * Convenience function which returns the reversed xored-hashed password for further |
| * processing in word documents 2007 and newer, which utilize a real hashing algorithm like sha1. |
| */ |
| public static String xorHashPasswordReversed(String password) { |
| int hashedPassword = createXorVerifier2(password); |
| |
| return String.format(Locale.ROOT, "%1$02X%2$02X%3$02X%4$02X" |
| , (hashedPassword) & 0xFF |
| , ( hashedPassword >>> 8 ) & 0xFF |
| , ( hashedPassword >>> 16 ) & 0xFF |
| , ( hashedPassword >>> 24 ) & 0xFF |
| ); |
| } |
| |
| /** |
| * Create the xor key for xor obfuscation, which is used to create the xor array (method 1) |
| * |
| * @see <a href="http://msdn.microsoft.com/en-us/library/dd924704.aspx">2.3.7.2 Binary Document XOR Array Initialization Method 1</a> |
| * @see <a href="http://msdn.microsoft.com/en-us/library/dd905229.aspx">2.3.7.4 Binary Document Password Verifier Derivation Method 2</a> |
| * |
| * @param password the password |
| * @return the xor key |
| */ |
| public static int createXorKey1(String password) { |
| // the xor key for method 1 is part of the verifier for method 2 |
| // so we simply chop it from there |
| return createXorVerifier2(password) >>> 16; |
| } |
| |
| /** |
| * Creates an byte array for xor obfuscation (method 1) |
| * |
| * @see <a href="http://msdn.microsoft.com/en-us/library/dd924704.aspx">2.3.7.2 Binary Document XOR Array Initialization Method 1</a> |
| * @see <a href="http://docs.libreoffice.org/oox/html/binarycodec_8cxx_source.html">Libre Office implementation</a> |
| * |
| * @param password the password |
| * @return the byte array for xor obfuscation |
| */ |
| public static byte[] createXorArray1(String password) { |
| if (password.length() > 15) { |
| password = password.substring(0, 15); |
| } |
| byte[] passBytes = password.getBytes(StandardCharsets.US_ASCII); |
| |
| // this code is based on the libre office implementation. |
| // The MS-OFFCRYPTO misses some infos about the various rotation sizes |
| byte[] obfuscationArray = new byte[16]; |
| System.arraycopy(passBytes, 0, obfuscationArray, 0, passBytes.length); |
| System.arraycopy(PAD_ARRAY, 0, obfuscationArray, passBytes.length, PAD_ARRAY.length-passBytes.length+1); |
| |
| int xorKey = createXorKey1(password); |
| |
| // rotation of key values is application dependent - Excel = 2 / Word = 7 |
| int nRotateSize = 2; |
| |
| byte[] baseKeyLE = {(byte) (xorKey & 0xFF), (byte) ((xorKey >>> 8) & 0xFF)}; |
| for (int i=0; i<obfuscationArray.length; i++) { |
| obfuscationArray[i] ^= baseKeyLE[i&1]; |
| obfuscationArray[i] = rotateLeft(obfuscationArray[i], nRotateSize); |
| } |
| |
| return obfuscationArray; |
| } |
| |
| /** |
| * The provided Unicode password string is converted to a ANSI string |
| * |
| * @param password the password |
| * @return the ansi bytes |
| * |
| * @see <a href="http://www.ecma-international.org/news/TC45_current_work/Office%20Open%20XML%20Part%204%20-%20Markup%20Language%20Reference.pdf">Part 4 - Markup Language Reference - Ecma International - section 3.2.29 (workbookProtection)</a> |
| */ |
| private static byte[] toAnsiPassword(String password) { |
| // TODO: charset conversion (see ecma spec) |
| |
| // Get the single-byte values by iterating through the Unicode characters. |
| // For each character, if the low byte is not equal to 0, take it. |
| // Otherwise, take the high byte. |
| byte[] arrByteChars = new byte[password.length()]; |
| |
| for (int i = 0; i < password.length(); i++) { |
| int intTemp = password.charAt(i); |
| byte lowByte = (byte)(intTemp & 0xFF); |
| byte highByte = (byte)((intTemp >>> 8) & 0xFF); |
| arrByteChars[i] = (lowByte != 0 ? lowByte : highByte); |
| } |
| |
| return arrByteChars; |
| } |
| |
| private static byte rotateLeft(byte bits, int shift) { |
| return (byte)(((bits & 0xff) << shift) | ((bits & 0xff) >>> (8 - shift))); |
| } |
| |
| private static short rotateLeftBase15Bit(short verifier) { |
| /* |
| * IF (Verifier BITWISE AND 0x4000) is 0x0000 |
| * SET Intermediate1 TO 0 |
| * ELSE |
| * SET Intermediate1 TO 1 |
| * ENDIF |
| */ |
| short intermediate1 = (short)(((verifier & 0x4000) == 0) ? 0 : 1); |
| /* |
| * SET Intermediate2 TO Verifier MULTIPLED BY 2 |
| * SET most significant bit of Intermediate2 TO 0 |
| */ |
| short intermediate2 = (short)((verifier<<1) & 0x7FFF); |
| /* |
| * SET Intermediate3 TO Intermediate1 BITWISE OR Intermediate2 |
| */ |
| return (short)(intermediate1 | intermediate2); |
| } |
| } |