Hi everyone,
I would like to know how can I generate a random pre-master key PMK in java? (related in key exchange and authentication) Is it similar with other randam key generating? What particularly is a pre master key?
Thanks, Sebby.
A:
It looks to me like you are trying to make your own crypto. If that's the case, please don't do it. That's the #1 crypto advice anyone will give you.
If you want to re-implement TLS or something similar, I suggest that you forget your attempt and use a well-tested library. If you MUST implement it, then please take the time to read the specs carefully. They will explain what each step is and how to compute it.
If the only thing you want to a a good bunch of random bytes, SecureRandom is the API to use.
mlaverd
2010-04-22 04:17:37
hi, thanks a lot for your reply. i now used the following code and could you please let me know that if it is a correct way to generate a PM-Key?? `try {<br/> KeyGenerator keyGen = KeyGenerator.getInstance("HmacMD5");<br/> SecretKey pmkey = keyGen.generateKey();<br/> byte[] PMKey = pmkey.getEncoded(); <br/> strPMK = MessageDigestAlgorithm.toHexString(PMKey);<br/> tv.append("\nPre-Master Key in hex: " + strPMK);<br/> }catch (NoSuchAlgorithmException e) {<br/> // TODO Auto-generated catch block e.printStackTrace(); <br/> }`
sebby_zml
2010-04-29 01:59:34
`try { KeyGenerator keyGen = KeyGenerator.getInstance("HmacMD5"); SecretKey pmkey = keyGen.generateKey(); byte[] PMKey = pmkey.getEncoded(); strPMK = MessageDigestAlgorithm.toHexString(PMKey); tv.append("\nPre-Master Key in hex: " + strPMK);}catch (NoSuchAlgorithmException e) { // TODO Auto-generated catch block e.printStackTrace();}`
sebby_zml
2010-04-29 02:05:08
I see a few issues with the code. 1) you're using MD5, which is really not future proof. Try something from the SHA-2 family instead. 2) `MessageDigestAlgorithm` is not a standard class, I don't know what it does... 3) You generate a secret key, not a pre-master secret. A pre-master secret only needs a `SecureRandom`. The pre-master secret is something specific from cryptographic protocols like SSL/TLS... are you mixing up pre-master secret with secret key?I think you need to explain your requirement/use case in more details here...
mlaverd
2010-04-29 03:11:18