Java Zip4jConstants.AES_STRENGTH_256屬性代碼示例

public AESEncrpyter(char[] password, int keyStrength) throws ZipException {
	if (password == null || password.length == 0) {
		throw new ZipException("input password is empty or null in AES encrypter constructor");
	}
	if (keyStrength != Zip4jConstants.AES_STRENGTH_128 && 
			keyStrength != Zip4jConstants.AES_STRENGTH_256) {
		throw new ZipException("Invalid key strength in AES encrypter constructor");
	}
	
	this.password = password;
	this.keyStrength = keyStrength;
	this.finished = false;
	counterBlock = new byte[InternalZipConstants.AES_BLOCK_SIZE];
	iv = new byte[InternalZipConstants.AES_BLOCK_SIZE];
	init();
}
 

private AESExtraDataRecord generateAESExtraDataRecord(ZipParameters parameters) throws ZipException {
	
	if (parameters == null) {
		throw new ZipException("zip parameters are null, cannot generate AES Extra Data record");
	}
	
	AESExtraDataRecord aesDataRecord = new AESExtraDataRecord();
	aesDataRecord.setSignature(InternalZipConstants.AESSIG);
	aesDataRecord.setDataSize(7);
	aesDataRecord.setVendorID("AE");
	// Always set the version number to 2 as we do not store CRC for any AES encrypted files
	// only MAC is stored and as per the specification, if version number is 2, then MAC is read
	// and CRC is ignored
	aesDataRecord.setVersionNumber(2); 
	if (parameters.getAesKeyStrength() == Zip4jConstants.AES_STRENGTH_128) {
		aesDataRecord.setAesStrength(Zip4jConstants.AES_STRENGTH_128);
	} else if (parameters.getAesKeyStrength() == Zip4jConstants.AES_STRENGTH_256) {
		aesDataRecord.setAesStrength(Zip4jConstants.AES_STRENGTH_256);
	} else {
		throw new ZipException("invalid AES key strength, cannot generate AES Extra data record");
	}
	aesDataRecord.setCompressionMethod(parameters.getCompressionMethod());
	
	return aesDataRecord;
}
 

private int calculateAESSaltLength(AESExtraDataRecord aesExtraDataRecord) throws ZipException {
	if (aesExtraDataRecord == null) {
		throw new ZipException("unable to determine salt length: AESExtraDataRecord is null");
	}
	switch (aesExtraDataRecord.getAesStrength()) {
	case Zip4jConstants.AES_STRENGTH_128:
		return 8;
	case Zip4jConstants.AES_STRENGTH_192:
		return 12;
	case Zip4jConstants.AES_STRENGTH_256:
		return 16;
	default:
		throw new ZipException("unable to determine salt length: invalid aes key strength");
	}
}
 

private void init() throws ZipException {
	switch (keyStrength) {
	case Zip4jConstants.AES_STRENGTH_128:
		KEY_LENGTH = 16;
		MAC_LENGTH = 16;
		SALT_LENGTH = 8;
		break;
	case Zip4jConstants.AES_STRENGTH_256:
		KEY_LENGTH = 32;
		MAC_LENGTH = 32;
		SALT_LENGTH = 16;
		break;
	default:
		throw new ZipException("invalid aes key strength, cannot determine key sizes");
	}
	
	saltBytes = generateSalt(SALT_LENGTH);
	byte[] keyBytes = deriveKey(saltBytes, password);
	
	if (keyBytes == null || keyBytes.length != (KEY_LENGTH + MAC_LENGTH + PASSWORD_VERIFIER_LENGTH)) {
		throw new ZipException("invalid key generated, cannot decrypt file");
	}
	
	aesKey = new byte[KEY_LENGTH];
	macKey = new byte[MAC_LENGTH];
	derivedPasswordVerifier = new byte[PASSWORD_VERIFIER_LENGTH];
	
	System.arraycopy(keyBytes, 0, aesKey, 0, KEY_LENGTH);
	System.arraycopy(keyBytes, KEY_LENGTH, macKey, 0, MAC_LENGTH);
	System.arraycopy(keyBytes, KEY_LENGTH + MAC_LENGTH, derivedPasswordVerifier, 0, PASSWORD_VERIFIER_LENGTH);
	
	aesEngine = new AESEngine(aesKey);
	mac = new MacBasedPRF("HmacSHA1");
	mac.init(macKey);
}
 

private void init(byte[] salt, byte[] passwordVerifier) throws ZipException {
	if (localFileHeader == null) {
		throw new ZipException("invalid file header in init method of AESDecryptor");
	}
	
	AESExtraDataRecord aesExtraDataRecord = localFileHeader.getAesExtraDataRecord();
	if (aesExtraDataRecord == null) {
		throw new ZipException("invalid aes extra data record - in init method of AESDecryptor");
	}
	
	switch (aesExtraDataRecord.getAesStrength()) {
	case Zip4jConstants.AES_STRENGTH_128:
		KEY_LENGTH = 16;
		MAC_LENGTH = 16;
		SALT_LENGTH = 8;
		break;
	case Zip4jConstants.AES_STRENGTH_192:
		KEY_LENGTH = 24;
		MAC_LENGTH = 24;
		SALT_LENGTH = 12;
		break;
	case Zip4jConstants.AES_STRENGTH_256:
		KEY_LENGTH = 32;
		MAC_LENGTH = 32;
		SALT_LENGTH = 16;
		break;
	default:
		throw new ZipException("invalid aes key strength for file: " + localFileHeader.getFileName());
	}
	
	if (localFileHeader.getPassword() == null || localFileHeader.getPassword().length <= 0) {
		throw new ZipException("empty or null password provided for AES Decryptor");
	}
	
	byte[] derivedKey = deriveKey(salt, localFileHeader.getPassword());
	if (derivedKey == null || 
			derivedKey.length != (KEY_LENGTH + MAC_LENGTH + PASSWORD_VERIFIER_LENGTH)) {
		throw new ZipException("invalid derived key");
	}
	
	aesKey = new byte[KEY_LENGTH];
	macKey = new byte[MAC_LENGTH];
	derivedPasswordVerifier = new byte[PASSWORD_VERIFIER_LENGTH];
	
	System.arraycopy(derivedKey, 0, aesKey, 0, KEY_LENGTH);
	System.arraycopy(derivedKey, KEY_LENGTH, macKey, 0, MAC_LENGTH);
	System.arraycopy(derivedKey, KEY_LENGTH + MAC_LENGTH, derivedPasswordVerifier, 0, PASSWORD_VERIFIER_LENGTH);
	
	if (derivedPasswordVerifier == null) {
		throw new ZipException("invalid derived password verifier for AES");
	}
	
	if (!Arrays.equals(passwordVerifier, derivedPasswordVerifier)) {
		throw new ZipException("Wrong Password for file: " + localFileHeader.getFileName(), ZipExceptionConstants.WRONG_PASSWORD);
	}
	
	aesEngine = new AESEngine(aesKey);
	mac = new MacBasedPRF("HmacSHA1");
	mac.init(macKey);
}