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3

The authentication tag is defined as an output parameter in GCM (see section 7, step 7 of NIST SP 800-38D). In all the API's I've encountered it's appended to the ciphertext. Where it is actually placed is up to the protocol designer. The protocol designer may well consider the place behind the ciphertext as ad hoc default though. The name "tag" of course ...


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You benchmarked a highly optimized AES implementation against a reference implementation of CLEFIA: * NOTICE * This reference code is written for a clear understanding of the CLEFIA * blockcipher algorithm based on the specification of CLEFIA. * Therefore, this code does not include any optimizations for * high-speed or low-cost implementations or any ...


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It you need a deterministically derived key for AES, the DRBG algorithms of NIST SP 800-90A are suitable, and their output is directly usable as an AES key. An example use case is when computing an AES session key from a longer-term master key, and the nonce corresponding to that session. AES will expand its key (128, 192 or 256-bit) to 128-bit subkeys (one ...


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No. First, you've exposed a padding oracle by using unauthenticated AES. Secondly, you've not authenticated the devices: it's easy to mount a man in the middle attack. Thirdly, I don't understand the role of changing parameters all the time in your protocol.


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Yes this would work as stated by you. Explanation: If you're using a library supporting ECB (which you are actually using in this example) you can input the whole 32 bytes of plaintext and will receive the corresponding 32 bytes of ciphertext. Splitting the operation into two calls doesn't make any difference for libraries as internally they do nothing ...


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Cipher Feedback mode turns the block cipher (AES) into a self-synchronizing stream cipher which feeds back the full ciphertext block as the next IV. If you encrypt something smaller than a multiple of the block size, it will not use all of the block cipher output to create the ciphertext, just the amount it needs. Therefore there is not a padding ...


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I would prefer to use standardized (like FIPS 140-2) secure random generator, since the whole point is to secure the encryption key. Of course, you might want to check this website for reference: http://www.cryptosys.net/rng_algorithms.html



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