Question

I have a bash script that uses the openssl tool to encrypt.

#!/bin/bash

key128="1234567890123456"
iv="1234567890123456"
openssl enc -aes-128-cbc -in test -out test.enc -K $key128 -iv $iv

And Java code that tries to decrypt the file produced by the script.

public class crypto {

    public static void main( String[] args )
    {
        try {
            File f = new File("test.enc");
            Cipher c;
            Key k;
            String secretString = "01020304050607080900010203040506";
            String ivString = "01020304050607080900010203040506";
            byte[] secret = hexStringToByteArray(secretString);
            byte[] iv = hexStringToByteArray(ivString);

            c = Cipher.getInstance("AES/CBC/PKCS5Padding");
            k = new SecretKeySpec(secret, "AES");
            c.init(Cipher.DECRYPT_MODE, k, new IvParameterSpec(iv));

            CipherInputStream cis = new CipherInputStream(new FileInputStream(f), c);
            BufferedReader br = new BufferedReader(new InputStreamReader(cis));

            String line;
            while ((line = br.readLine()) != null) {
                System.out.println(line);
            }
            br.close();
        } catch (IOException e) {
            System.out.println(e.getMessage());
        } catch (NoSuchAlgorithmException e) {
            System.out.println(e.getMessage());
        } catch (NoSuchPaddingException e) {
            System.out.println(e.getMessage());
        } catch (InvalidKeyException e) {
            System.out.println(e.getMessage());
        } catch (InvalidAlgorithmParameterException e) {
            System.out.println(e.getMessage());
        }

    }

    public static byte[] hexStringToByteArray(String s) {
        int len = s.length();
        byte[] data = new byte[len / 2];
        for (int i = 0; i < len; i += 2) {
            data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
                                 + Character.digit(s.charAt(i+1), 16));
        }
        return data;
    }
}
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When I run the Java code, it doesn’t print anything. Is there a mismatch between the script and Java code?

A secondary question is whether I can rewrite this to use password instead of key/iv. In order to do that, is there a way to know the iv that openssl uses for a given password?

Answer 1

As @Polynomial mentioned above, the keys and iv’s don’t match between the bash script and Java code. Changing the bash script to the following solves the problem.

#!/bin/bash

key128="01020304050607080900010203040506"
iv="01020304050607080900010203040506"
openssl enc -aes-128-cbc -in test -out test.enc -K $key128 -iv $iv

If openssl is executed in the following way, it will use a password, and print the key and iv used. That key and iv can be substituted in the Java program above.

openssl enc -nosalt -aes-128-cbc -in test -out test.enc -p