SHA-256 is part of the SHA-2 family of hash functions with a 256-bit output and a 128-bit security level.

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Is it possible to derive the midstate of a sha256 hash?

Let's say I have an unknown string with the known sha256-hash of it. I was wondering if it was possible to now calculate the sha256 of the concatenation of the unknown string and "abc". (In PHP: ...
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Questions about adding 0s to the key in HMAC and how it compares to SHAd

I noticed some strange behaviour when adding different characters onto the end of the key then inputting it into HMAC and I was getting the same output hash. First I generated a key and message to ...
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Is this a secure (and correct) sign-then-encrypt technique for transferring messages?

After reading some information on the way iMessage works I have been working on writing some code to try my hand at securely transferring messages in a similar manner and I wanted to confirm that the ...
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Sane implementations of Bitcoin cryptography routines w.r.t. side-channel attacks

Bitcoin uses SHA-256, Base58Check, ECDSA (Sep256k1) and RIPEMD-160 as the basis of its encryption (see this article for a short guide on how addresses are created). I would like to create an ...