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Jan
19
comment Understanding the cryptography used in a file
I'm sorry but this question is neither on-topic nor suitable for Stack Exchange. What you have here is a reverse engineering problem, not a cryptography problem. Reverse Engineering would be a more appropriate forum, but don't just re-ask there — this question is too broad, essentially you're asking us to tell you all we know about reverse engineering. You need to do some of the job of breaking this up into manageable parts. Do note that attacking such problems by looking at one data dump is rarely useful, usually you need to confront multiple datasets or observe the code in a debugger.
Jan
13
comment Should I use RSA encryption since RSA is said to be broken by NSA?
If you're typing the letters RSA into your code, you're doing it wrong. Cryptography is not a magic bullet and is hard to get right. Use protocols and libraries that experts have written and let them pick the algorithm.
Jan
1
comment TPM's monotonic counters
@MaartenBodewes On the contrary, this is about the implementation of a cryptography-related protocol (for storage integrity). It would be off-topic on Information Security since this isn't about the security of the protocol but about how it works.
Dec
27
comment Prevent double-spending with decentralized digital currencies without all transactions being public?
Mentioning Zerocash is interesting, but unfortunately your answer doesn't explain the crucial part: why is it that before spending a coin, I can prove that I own it, but after spending it that proof no longer works?
Dec
15
comment Cyclic group collision resistant keyed cryptographic hash function
Please post text rather than an image. An image is hard to read at the wrong resolution, impossible to read if you're blind, impossible to search, impossible to copy from… You can use mathematical notations with MathJax's LaTeX-like syntax.
Dec
14
comment Hash functions vs Stream Ciphers in terms of Speed
I don't understand your revised question better than the original. If you want variable-sized output, what does this have to do with a hash? You seem to be asking which is faster, an apple or an orange.
Dec
12
comment Help with RSA-2048 crypto ransom virus
I'm voting to close this question as off-topic because it's about recovering from malware, not about cryptography.
Dec
1
comment Checking the integrity of RSA public key
How about the attacker sending chosen ciphertexts or plaintexts with varying values of $e$ (assuming a scenario where the attacker can force the cryptographic module to reload $e$ from the breached storage at will)? Could that reveal information that fixed-$e$ attacks wouldn't?
Nov
22
comment Probability of guessing random 128-bit AES key
I'm voting to close this question as off-topic because it is about counting, with only a superficial application to cryptography.
Nov
21
comment How does generating random numbers “remove entropy from your system”?
“once you've used a seed you should really throw it out and collect another one”: that's grossly misleading. Once you've used a seed, you throw it out, but you can keep using the PRNG seeded from that seed for a very long time.
Nov
19
comment Keyless integrity checking with SHA-256
Why don't you store the size as well as the hash? It's usually useful for other reasons (allocating sizes, detecting obvious transmission errors, etc.).
Nov
6
comment gpg --gen-random quality level: is higher “better”?
/dev/random does not really have higher guarantees than /dev/urandom (it's only better in one specific case, which is a newly-installed machine).
Oct
22
comment Memory hard password based key derivation functions?
Everything but your last paragraph is irrelevant: the question isn't why memory-hard functions are useful but how to design one based on Skein. The function you propose may or may not be relevant, but since you say nothing about it other than giving a link, your post does not answer the question at all. Please take a moment to review our guidelines on how to answer.
Oct
14
comment RSA Signature Verification Implementation on Cortex M0
We don't do library recommendations here, so I edited your question to remove that part. You could ask for existing libraries on Software Recommendations.
Oct
1
comment Encrypting a 160-bit plaintext into a 160 bit ciphertext with a 128-bit Block Cipher
I'm voting to close this question even though it is on-topic because it has also been posted on Computer Science and has been answered there. Please do not post the same question on multiple sites.
Sep
30
comment generate RSA public key having public modulus and exponent
The public key is the modulus and exponent. The tool you want to use probably needs a format that isn't the one you present in the question. But your question gives no clue as to what format you want. It's also not clear what you want to do in the first place. Encrypting files is pointless if you can't decrypt them. Who has the private key and what format can they decrypt? This determines what format you would encrypt in. Then, asymmetric cryptography isn't used to encrypt files, only to encrypt very small messages such as a single-use symmetric key used only to encrypt one file.
Sep
30
comment Why is GCM only usable for ciphers with a 128-bit block size?
For “what is it”, what reference materials (e.g. Wikipedia, the NIST specification) have you read, and what part don't you understand?
Sep
27
comment Do we have to consider the cryptographic properties of the decryption, if we're only using the encryption?
I don't understand the question. Does decryption matter for what? Can we ignore decryption for what?
Sep
24
comment How is a public/private key pair generated from a Diffe-Hellman key exchange?
There are plenty of different protocols. The protocol you describe uses a key pair to allow one party to encrypt data which only the other party can decrypt. DH isn't useful for that. It's useful for obtaining a shared secret key. I really can't explain all possible uses of cryptography in a comment or even in an answer. Rest assured that you will discover more protocols as the course progresses.
Sep
24
comment How is a public/private key pair generated from a Diffe-Hellman key exchange?
No, Alice does not encrypt her message with Bob's public key. That's what is done for encryption algorithms such as RSA. But Diffie-Hellman is a key exchange algorithm, not an encryption algorithm. DH isn't for doing asymmetric encryption or signature, it generates a shared secret. The shared secret can be used for encryption, but then it's symmetric encryption (e.g. with AES).