How to use the algorithm "PBEWithHmacSHA512AndAES_256"?

Question

I use Java encryption and cannot find a way to use the PBEWithHmacSHA512AndAES_256 algorithm correctly.

Encryption seems to work fine, but I can't properly initialize the decryption cipher.

The following is a short program that demonstrates the problem. In particular, see the comment “PROBLEM”.

Note: I saw this very useful answer , and I can make this circuit work, but I'm curious to know what I'm doing wrong here.

import java.nio.charset.StandardCharsets; import javax.crypto.Cipher; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.PBEKeySpec; import javax.crypto.spec.PBEParameterSpec; public final class CryptQuestion { private static final String ALGORITHM = "PBEWithHmacSHA512AndAES_256"; private static final int ITERATIONS = 1000; // Aside: not sure what is a good number, here. public static void main(final String[] args) throws Exception { final String message = "This is the secret message... BOO!"; System.out.println("Original : " + message); final byte[] messageBytes = message.getBytes(StandardCharsets.US_ASCII); final String password = "some password"; final byte[] salt = "would be random".getBytes(StandardCharsets.US_ASCII); // Create the Key final SecretKeyFactory factory = SecretKeyFactory.getInstance(ALGORITHM); final PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, ITERATIONS); SecretKey key = factory.generateSecret(keySpec); // Build the encryption cipher. final Cipher cipherEncrypt = Cipher.getInstance(ALGORITHM); cipherEncrypt.init(Cipher.ENCRYPT_MODE, key); // Encrypt! final byte[] ciphertext = cipherEncrypt.doFinal(messageBytes); final byte[] iv = cipherEncrypt.getIV(); // Now for decryption... The receiving end will have as input: // * ciphertext // * IV // * password // * salt // We just re-use 'key' from above, since it will be identical. final PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, ITERATIONS); final IvParameterSpec ivParamSpec = new IvParameterSpec(iv); // Build the decryption cipher. final Cipher cipherDecrypt = Cipher.getInstance(ALGORITHM); // PROBLEM: If I pass "ivParamSpec", I get "java.security.InvalidAlgorithmParameterException: Wrong parameter type: PBE expected" // Whereas if I pass pbeParamSpec, I get "java.security.InvalidAlgorithmParameterException: Missing parameter type: IV expected" // What to do? cipherDecrypt.init( Cipher.DECRYPT_MODE, key, ivParamSpec //pbeParamSpec ); final String decrypted = new String( cipherDecrypt.doFinal(ciphertext), StandardCharsets.US_ASCII); System.out.println("Decrypted: " + decrypted); } } 

Answer 1

 // PROBLEM: If I pass "ivParamSpec", I get "java.security.InvalidAlgorithmParameterException: Wrong parameter type: PBE expected" // Whereas if I pass pbeParamSpec, I get "java.security.InvalidAlgorithmParameterException: Missing parameter type: IV expected" // What to do? cipherDecrypt.init( Cipher.DECRYPT_MODE, key, ivParamSpec //pbeParamSpec ); 

Use AlgorithmParameters from Cipher Encryption:

 cipherDecrypt.init( Cipher.DECRYPT_MODE, key, cipherEncrypt.getParameters() ); 

If you need a cleaner method that does not include cipherEncrypt on the decryption site, save the algorithm parameters as a byte and pass them along with the key data:

 byte[] algorithmParametersEncoded = cipherEncrypt.getParameters().getEncoded(); 

and restore them to the decryption site, thus:

 AlgorithmParameters algorithmParameters = AlgorithmParameters.getInstance(ALGORITHM); algorithmParameters.init(algorithmParametersEncoded); 

and use AlgorithmParameters as the arguments argument to Cipher.init() above.