I want to use the following code for a high-concurrency application where certain data must be encrypted and decrypted. So I need to know what part of this code should be synchronized, if any, to avoid unpredictable issues.
public class DesEncrypter {
Cipher ecipher;
Cipher dcipher;
// 8-byte Salt
byte[] salt = {
(byte)0xA9, (byte)0x9B, (byte)0xC8, (byte)0x32,
(byte)0x56, (byte)0x35, (byte)0xE3, (byte)0x03
};
int iterationCount = 19;
DesEncrypter(String passPhrase) {
try {
// Create the key
KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance( "PBEWithMD5AndDES").generateSecret(keySpec);
ecipher = Cipher.getInstance(key.getAlgorithm());
dcipher = Cipher.getInstance(key.getAlgorithm());
// Prepare the parameter to the ciphers
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
// Create the ciphers
ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
} catch (...)
}
public String encrypt(String str) {
try {
// Encode the string into bytes using utf-8
byte[] utf8 = str.getBytes("UTF8");
// Encrypt
byte[] enc = ecipher.doFinal(utf8);
// Encode bytes to base64 to get a string
return new sun.misc.BASE64Encoder().encode(enc);
} catch (...)
}
public String decrypt(String str) {
try {
// Decode base64 to get bytes
byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);
// Decrypt
byte[] utf8 = dcipher.doFinal(dec);
// Decode using utf-8
return new String(utf8, "UTF8");
} catch (...)
}
}
If I create a new cipher in the encrypt() and decrypt() methods for each invocation, then I can avoid concurrency problems, I'm just not sure if there's a lot of overhead in getting a new instance of a cipher for each invocation.
public String encrypt(String str) {
try {
// Encode the string into bytes using utf-8
byte[] utf8 = str.getBytes("UTF8");
// Encrypt
//new cipher instance
ecipher = Cipher.getInstance(key.getAlgorithm());
byte[] enc = ecipher.doFinal(utf8);
// Encode bytes to base64 to get a string
return new sun.misc.BASE64Encoder().encode(enc);
} catch (...)
The Cipher
object is not going to be thread-safe, because it retains internal state about the encryption process. That applies to your DesEncrypter
class as well - each thread will need to use its own instance of DesEncrypter
, unless you synchonize the encode
and decode
methods.
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