Henno Brandsma
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 Feb 6 revised How to break Universal Re-Encryption algorithm? deleted 1 character in body Feb 6 answered How to break Universal Re-Encryption algorithm? Feb 6 comment How to break Universal Re-Encryption algorithm? Possibly relevant crypto.stackexchange.com/a/18954/553 Jan 9 revised What are the main weaknesses of a Playfair cipher, if any? slight expansion Dec 23 comment SHA256 message bytes Indeed. It's a key expansion in a way: the message is the key for the cipher (at the core of SHA26) and is expanded from 16 32-bit words to 64 32-bit words. The state is then handled as the message (with a xor feed forward for non-reversibility) Dec 22 answered AES Inverse Key Schedule Dec 17 comment Factorizing N to derive D long is also not big enough. Use gmp or some other bignum library, if you want C. Of course Python will do this OK, as it has bignums built in. Dec 14 awarded Necromancer Dec 12 comment Message exchange with textbook RSA I agree, but it's just a conceptual exercise, I suppose. It might be part of some algebra course without crypto focus, e.g., so padding, replay attacks etc. are not relevant, but just the application of some algebra theory that was just treated, e.g. I didn;t want to get things in that the OP wouldn't know about. Dec 12 answered Message exchange with textbook RSA Dec 12 answered Attack on textbook RSA with small messages Dec 11 comment Why does GPG ciphertext length differ with fixed plaintext length? The base64 difference is expected. If we input $n$ bytes, we have $4(n/3 + 1)$ output bytes if $n$ is not evenly divided by 3, and $4(n/3)$ otherwise. So a difference of 4 between 389 (remainder 2) and 387 (no remainder) is clear, and cannot be helped. That is how base64 encoding works. Dec 11 comment Why does GPG ciphertext length differ with fixed plaintext length? Can you give the complete gpg command ? Giving the string on the command line interprets it as a filename, so you must do something else. All details can matter. Dec 11 comment Why does GPG ciphertext length differ with fixed plaintext length? Just a remark: base64 is not encryption, just a standard way to transfer/display binary data as text data. Dec 8 answered Different tools return different ciphertext value for equal input Dec 8 comment Different tools return different ciphertext value for equal input Dec 8 comment Different tools return different ciphertext value for equal input Can you load your own key into the HSM? Then it would be testable Dec 8 comment Different tools return different ciphertext value for equal input The online tool seems to use ASCII values as the key (so it's crap, basically), if the test vectors below on the page are to be believed. So your hex input is interpreted as ASCII, not as bytes encoded as hex-ASCII. Dec 8 comment Different tools return different ciphertext value for equal input You cannot without the actual key bytes that are used, essentially. Dec 8 comment Different tools return different ciphertext value for equal input It seems strange that an HSM could leak its key, which is unusual. Moreover, your keyvalue is, after the first two bytes 86 01 the ASCII "nerated DES3 Key", followed by null bytes. So I don't think it's the actual key, but something else. The first two bytes "ought' to be 47 65 for "Ge", to make even more sense