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AES Encryption with HMAC Integrity in Java

 April 19th, 2015Apr 19th, 2015        20

UPDATED: 12th August 2016

I recently came across a requirement to provide password based encryption and decryption of data in a Java program. I initially assumed I just needed to pass my data through some internal Java “encrypt (plaintext, password)” type function and all would be fine. Unfortunately I found it isn’t quite as simple as this and there are quite a few pitfalls you need to overcome if you want to do this securely and properly.

I also wanted to work within the limitations of Java and only use native libraries (e.g. “javax.crypto”), which rules out the popular Bouncy Castle cryptographic library – rolling your own crypto functions is also a very bad idea (repeat “very bad idea“) as even the experts can get it wrong sometimes. I also wanted to ensure it worked with Java 7, which rules out some of the newer more modern modes of AES like GCM (Galois/Counter Mode).

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General Cryptography Java