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1d
comment Need CryptDeriveKey AES implementation in C#
Microsoft does document their "CryptDeriveKey" function. Check msdn. It's their own invention, not standard based.
1d
comment Please help me decrypt this Classical Cipher
Looks like a transposition to me
1d
comment Linear cryptanalysis complete key guessing
You guess the other bits as well, after determining the subkeys.
Feb
6
revised How to break Universal Re-Encryption algorithm?
added 5 characters in body
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
Let us continue this discussion in chat.