AES does not expand data. Moreover, the output will not generally be compressible; if you intend to compress your data, do so before encrypting it. However, note that AES encryption is usually combined with padding, which will increase the size of the data (though only by a few bytes).
Things to know in general: Key != Password SecretKeySpec expects a key, not a password. See below It might be due to a policy restriction that prevents using 32 byte keys. See other answer on that In your case The problem is number 1: you are passing the password instead of the key. AES only … Read more
Given the popularity of Python, at first I was disappointed that there was no complete answer to this question to be found. It took me a fair amount of reading different answers on this board, as well as other resources, to get it right. I thought I might share the result for future reference and … Read more
I would use your suggested code, but with a slight simplification: KeyGenerator keyGen = KeyGenerator.getInstance(“AES”); keyGen.init(256); // for example SecretKey secretKey = keyGen.generateKey(); Let the provider select how it plans to obtain randomness – don’t define something that may not be as good as what the provider has already selected. This code example assumes (as … Read more
This error means that your Java virtual machine uses a policy that only allows restricted cryptography key sizes due to US export laws. Java 9 and higher The Unlimited Strength Jurisdiction Policy Files are included with Java 9 and used by default (see Security Updates in the Java 9 Migration Guide). If you get this … Read more
Compress first. Once you encrypt the file you will generate a stream of seemingly random data, which will be not be compressible. The compression process depends on finding compressible patterns in the data.
Please use an existing secure PHP encryption library It’s generally a bad idea to write your own cryptography unless you have experience breaking other peoples’ cryptography implementations. None of the examples here authenticate the ciphertext, which leaves them vulnerable to bit-rewriting attacks. If you can install PECL extensions, libsodium is even better <?php // PECL … Read more
Official document of Crypto++ AES is a good start. And from my archive, a basic implementation of AES is as follows: Please refer here with more explanation, I recommend you first understand the algorithm and then try to understand each line step by step. #include <iostream> #include <iomanip> #include “modes.h” #include “aes.h” #include “filters.h” int … Read more
AES has a fixed block size of 16 bytes regardless of key size. Assuming you use PKCS 5/7 padding, use this formula: cipherLen = (clearLen/16 + 1) * 16; Please note that if the clear-text is a multiple of the block size then a whole new block is needed for padding. For example, if your … Read more
Neither implementation you give in your question is entirely correct, and neither implementation you give should be used as is. In what follows, I will discuss aspects of password-based encryption in Android. Keys and Hashes I will start discussing the password-based system with salts. The salt is a randomly generated number. It is not “deduced”. … Read more