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Jan
16
comment I have a keyword and cipher text but cannot decode it please help!
Don't vandalize your own post.
Jan
16
revised I have a keyword and cipher text but cannot decode it please help!
rolled back to a previous revision
Jan
16
revised I have a keyword and cipher text but cannot decode it please help!
rolled back to a previous revision
Jan
16
comment Help converting sha256 to 32-bit stream
I think this is just a weird formulation for "SHA256 outputs a 32 bytes/256 bits which you should then encode with BASE64".
Jan
16
comment Can AES in CCM or GCM counter mode interoperate with AES in “plain” counter mode (CTR)?
Implementing CTR on top of ECB is probably easier than hacking GCM to become CTR.
Jan
16
comment Is ASCON cipher broken?
It only talks about round reduced versions, so it's not a break.
Jan
15
comment Public key encryption and big files with NaCL
1) Salsa20 is a stream cipher, so nonce reuse behaves like one-time-pad key-reuse. crypto.stackexchange.com/… 2) The Poly1305 MAC is a one-time MAC (wegman-carter), so nonce reuse leaks the MAC key for that nonce.
Jan
15
comment Public key encryption and big files with NaCL
1) Do you use a two part nonce, so you can use a different counter as nonce input for each chunk? Reusing the full nonce is fatal. 2) It's essential to use a special counter/nonce for the chunk containing the hash 3) I'd replace the hash by the file size
Jan
15
reviewed Leave Open Entropy in relation to computer security
Jan
15
reviewed Reviewed Simplifying the zero-knowledge proof example?
Jan
15
reviewed Reviewed Unbreakable code and mathematical impossibility
Jan
14
comment Programming language for modular arithmetic over large numbers
Most major languages either ship with built in bigintegers or have third party implementations. I've heard good things about NTL and it has the additional advantage that it's not merely a biginteger library but contains support for a lot of advanced mathematical features that are useful for cryptography.
Jan
14
comment Programming language for modular arithmetic over large numbers
This question appears to be off-topic because it is about 1) a programming problem, not a crypto problem. 2) A recommendation question with many possible answers, and thus not suitable for stackoverflow either.
Jan
14
comment What is a tweakable block cipher?
@figlesquidge That construction is trivially distinguishable from a proper tweakable cipher. There is a reason that XTS and OCB are more complex.
Jan
12
comment Using hash of plaintext as nonce in NaCl secretbox- bad idea?
An unkeyed hash of the plaintext leaks a lot of information about the plaintext.
Jan
12
comment Where are the ChaCha20 test vectors/examples?
Note that this is no RFC yet, it's only a draft.
Jan
12
revised Base64 with shuffled alphabet
deleted 38 characters in body; edited tags; edited title
Jan
9
comment Which block cipher mode does the experts use?
They use the mode that fits the requirements. Padding not working correctly is not a good reason to ditch CBC, you need to fix the code. Apart from padding there are several other things you'll need to get right, such as authentication/integrity checking and proper IV generation. Adding and removing padding is the easiest of these.
Jan
9
comment How secure is file header encryption for large files?
@Erode Then why do you need such a high performance? A 2GB file will contain a video far longer than 15s or even 3m, so decryption cost should be negligible compared to the video decoding cost.
Jan
9
comment How secure is file header encryption for large files?
What are you trying to achieve? That only your application can play these video files?