Decrypt Blowfish in Java (Generating a secret key in program)

Question

My professor gave us a decryption assignment in which we were given a list of "encrypted" phrases and told to decrypt them. One of them is in blowfish. Me and one of my classmates have tried all the possible keys that he might use. Thus I was going to make a program in Java that would go through all possible keys decrypt the string and then write the decrypted message out to a file. Only problem is all the online tutorials that i can find on writing blowfish in Java have this interface SecretKey being read in from a file.

My question is how do you generate a SecretKey in a program?

see http://stackoverflow.com/questions/5244950/encryption-with-blowfish-in-java, just generate random byte[] data as input (as a cs student you should be able to figure that out). — Johannes Rudolph, Mar 26 '11 at 22:52
Not every key possible no, but every key that we think he would use. Based off things he's said in class and lists of the most common passwords. — user678461, Mar 26 '11 at 22:53

score 2 · Accepted Answer · answered Mar 26 '11 at 23:08

2

This might help you:

byte[] key = getKey();
Cipher cipher = Cipher.getInstance("Blowfish");
SecretKeySpec keySpec = new SecretKeySpec(key, "Blowfish");
cipher.init(Cipher.DECRYPT_MODE, keySpec);

answered Mar 26 '11 at 23:08

WhiteFang34

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score 0 · Answer 2 · answered Mar 26 '11 at 22:58

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Here's the API you want to use. http://download.oracle.com/javase/6/docs/api/javax/crypto/spec/SecretKeySpec.html#SecretKeySpec%28byte%5b%5d,%20java.lang.String%29

answered Mar 26 '11 at 22:58

Mike Samuel

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score 0 · Answer 3 · answered Mar 26 '11 at 23:01

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Use a SecretKeySpec to generate a SecretKey using SecretKeyFactory.generate().

answered Mar 26 '11 at 23:01

Bombe

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Decrypt Blowfish in Java (Generating a secret key in program)

3 Answers3