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Mar
23
comment Length-preserving all-or-nothing transform
Interesting mismatch between 6 rounds from that paper and the 4 rounds to build a strong PRP from the Luby-Rackoff paper.
Mar
23
comment Can two files/strings have the same SHA-256 value?
The argument in your question proves the existence of collisions, using the Pigeonhole principle.
Mar
23
comment ECIES is must with Symmetric?(ECIES-AES or ECIES-TDES)
Do you have a source for the claim that the above algorithm is ECIES?
Mar
23
comment ECIES is must with Symmetric?(ECIES-AES or ECIES-TDES)
The first one looks like ElGamal encryption and not like ECIES to me.
Mar
23
comment Will changing the RSA Padding in OpenSSL cause issues?
To make matters worse, if you still support the old vulnerable algorithm, you'd probably still be vulnerable to padding oracles, even for data that was encrypted using the new algorithm as long as you use the same RSA key for both.
Mar
23
comment Will changing the RSA Padding in OpenSSL cause issues?
Presumably PKCS#1v1.5 to OAEP.
Mar
22
comment What is considered a “weak key” in AES?
It has no (known) weak keys. And even with DES, rejecting "weak" keys is silly.
Mar
22
comment Is there any benefit to verifying PKCS#7 padding when using AES CBC and HMAC?
Related question: Why verify padding at all?
Mar
22
comment What prevents a padding standard to cause a data loss?
Related question: Why can the last block contain a full block of padding in CBC Encryption?
Mar
22
comment Why can the last block contain a full block of padding in CBC Encryption?
Related question: What prevents a padding standard to cause a data loss?
Mar
22
comment What is the benefit of artificially padding messages?
Related question: Why can the last block contain a full block of padding in CBC Encryption?
Mar
22
comment What is the benefit of artificially padding messages?
CFB doesn't require padding.
Mar
22
comment Can the SHA256 hashes of consecutive integers be attacked?
Where "sufficiently large" is something of the order $n/k > 2^{80}$. Higher if you care about state level attackers.
Mar
21
comment What's the best way to pad a message?
IMO padding is a dubious approach in the first place. For encryption just use a random value uniformly distributed between 0 and n-1 and derive a key suitable for symmetric authenticated encryption from it via hashing (e.g. using HKDF) (known as RSA-KEM). For signing simply use a hash with an output as big as the modulus (Full-Domain-Hash FDH).
Mar
21
comment Can the SHA256 hashes of consecutive integers be attacked?
How big are $n$ and $k$?
Mar
19
comment How to deal with collisions in Bitcoin addresses?
Why is "it's very unlikely to happen" unsatisfactory to you? That statement is at the heart of all crypto.
Mar
18
comment Can double-encrypting be easier to break then either algorithm on its own?
Do you use independent keys?
Mar
18
comment Can double-encrypting be easier to break then either algorithm on its own?
Only if you mess up (e.g. by using a cipher that leaks information about the plaintext into the length of the ciphertext.)
Mar
17
comment Anonymity problem after voting with blind signatures
I don't see how any of that enables deanonymization.
Mar
17
comment Anonymity problem after voting with blind signatures
"Registrar can in cycle try to do $sm'_i \cdot sm_j^{-1} \pmod N$ to find some $r_k$" -- Can you explain why you expect this to have a higher success probability than generating a random $r$?