Question

all files in ~/Cipher/nsdl/crypto can be found here java files compiled with gcj, see compile.sh

nmint@nqmk-mint ~/Cipher/nsdl/crypto $ echo test | ./cryptTest encrypt deadbeefdeadbeefdeadbeefdeadbeef deadbeef Blowfish CBC > test null Exception in thread 'main' java.lang.IllegalStateException: cipher is not for encrypting or decrypting    at javax.crypto.Cipher.update(libgcj.so.81)    at javax.crypto.CipherOutputStream.write(libgcj.so.81)    at nsdl.crypto.BlockCrypt.encrypt(cryptTest)    at nsdl.crypto.cryptTest.main(cryptTest) 

BlockCrypt.java:

package nsdl.crypto;  import java.io.*; import java.security.spec.*; import javax.crypto.*; import javax.crypto.spec.*;  public class BlockCrypt { Cipher ecipher; Cipher dcipher; byte[] keyBytes; byte[] ivBytes; SecretKey key; AlgorithmParameterSpec iv; byte[] buf = new byte[1024];  BlockCrypt(String keyStr, String ivStr, String algorithm, String mode) {     try {         ecipher = Cipher.getInstance(algorithm + '/' + mode + '/PKCS5Padding');         dcipher = Cipher.getInstance(algorithm + '/' + mode + '/PKCS5Padding');          keyBytes = hexStringToByteArray(keyStr);         ivBytes = hexStringToByteArray(ivStr);          key = new SecretKeySpec(keyBytes, algorithm);         iv = new IvParameterSpec(ivBytes);          ecipher.init(Cipher.ENCRYPT_MODE, key, iv);         dcipher.init(Cipher.DECRYPT_MODE, key, iv);     } catch (Exception e) {         System.err.println(e.getMessage());     } }  public void encrypt(InputStream in, OutputStream out) {     try {         // out: where the plaintext goes to become encrypted         out = new CipherOutputStream(out, ecipher);          // in: where the plaintext comes from         int numRead = 0;         while ((numRead = in.read(buf)) >= 0) {             out.write(buf, 0, numRead);         }         out.close();     } catch (IOException e) {         System.err.println(e.getMessage());     } }  public void decrypt(InputStream in, OutputStream out) {     try {         // in: where the plaintext come from, decrypted on-the-fly         in = new CipherInputStream(in, dcipher);          // out: where the plaintext goes         int numRead = 0;         while ((numRead = in.read(buf)) >= 0) {             out.write(buf, 0, numRead);         }         out.flush();         out.close();     } catch (IOException e) {         System.err.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; } } 

cryptTest.java:

package nsdl.crypto;  import nsdl.crypto.BlockCrypt;  public class cryptTest {  public static void main (String args[]) {     if (args.length != 5) {         System.err.println('Usage: cryptTest (encrypt|decrypt) key iv algorithm mode');         System.err.println('Takes input from STDIN. Output goes to STDOUT.');     } else {         String operation = args[0];         String key = args[1];         String iv = args[2];         String algorithm = args[3];         String mode = args[4];         BlockCrypt blockCrypt = new BlockCrypt(key, iv, algorithm, mode);         if (operation.equalsIgnoreCase('encrypt')) {             blockCrypt.encrypt(System.in, System.out);         } else if (operation.equalsIgnoreCase('decrypt')) {             blockCrypt.decrypt(System.in, System.out);         } else {             System.err.println('Invalid operation. Use (encrypt|decrypt).');         }     } } } 

Answer 1

The Cipher, ecipher, is not initialized, and it throws an IllegalStateException when you try to use it as if it were initialized in ENCRYPT_MODE.

Note your catch block in the constructor of BlockCrypt. It is catching an exception with no message, and printing ‘null’ to System.err. Rather than aborting execution—perhaps by throwing an exception from the constructor—you keep sailing.

Replacing System.err.println(e.getMessage()) with e.printStackTrace() or at least System.err.println(e) should give you more detail. My guess is that ecipher.init() is throwing an exception because you’re providing a 32-bit IV instead of 64 bits.