/* ==================================================================== | |
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 | |
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Unless required by applicable law or agreed to in writing, software | |
distributed under the License is distributed on an "AS IS" BASIS, | |
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See the License for the specific language governing permissions and | |
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==================================================================== */ | |
package org.apache.poi.poifs.crypt; | |
import java.nio.charset.Charset; | |
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.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 class 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 | |
* @param hashAlgorithm | |
* @param salt | |
* @param spinCount | |
* @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 | |
* @param hashAlgorithm | |
* @param salt | |
* @param spinCount | |
* @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 | |
*/ | |
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 | |
* @param hashAlgorithm | |
* @param blockKey | |
* @param keySize | |
* @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 secrect 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 GeneralSecurityException | |
* @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 secrect 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 GeneralSecurityException | |
* @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 = new byte[size]; | |
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 = Thread.currentThread().getContextClassLoader(); | |
String bcProviderName = "org.bouncycastle.jce.provider.BouncyCastleProvider"; | |
Class<Provider> clazz = (Class<Provider>)cl.loadClass(bcProviderName); | |
Security.addProvider(clazz.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) { | |
byte[] arrByteChars = toAnsiPassword(password); | |
// SET Verifier TO 0x0000 | |
short verifier = 0; | |
if (!"".equals(password)) { | |
// 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) { | |
//Array to hold Key Values | |
byte[] generatedKey = new byte[4]; | |
//Maximum length of the password is 15 chars. | |
final int maxPasswordLength = 15; | |
if (!"".equals(password)) { | |
// 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 | |
for (int i = 0; i < arrByteChars.length; i++) { | |
int tmp = maxPasswordLength - arrByteChars.length + i; | |
for (int intBit = 0; intBit < 7; intBit++) { | |
if ((arrByteChars[i] & (0x0001 << intBit)) != 0) { | |
highOrderWord ^= ENCRYPTION_MATRIX[tmp][intBit]; | |
} | |
} | |
} | |
// 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 >>> 0 ) & 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(Charset.forName("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 | |
*/ | |
short intermediate3 = (short)(intermediate1 | intermediate2); | |
return intermediate3; | |
} | |
} |