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Jan
13
comment Difference between AES CMAC and AES HMAC?
Where did you read about AES HMAC? Perhaps you misunderstood and the source was talking about authenticated encryption that encrypts using AES (e.g. in CTR mode) and adds HMAC-SHA-* for integrity?
Jan
12
comment Faster alternative to HKDF
You're creating millions of subkeys per second? Could you elaborate a bit more on the use case and context? Is the master key fixed or different each time? How long are the derived keys?
Jan
12
comment What is the canonical way of creating merkle tree branches?
That depends on how you construct and balance the tree. For simple trees the size determines the structure and you'd only need to give the index of the leaf node to know which path leads to the root.
Jan
11
comment Encryption used in a commercial software product
c[i] = p[i] xor key[i mod 10]. Using xor is a common choice for synchronous stream ciphers‌​. A repeated key is used by the Vigenère cipher, though it's traditionally used with character-wise modular addition instead of bit-wise xor.
Jan
10
comment Elliptic ElGamal Public Key Cryptosystem doubt
@poncho That sounds like a notation issue to me. Since $4^2 \equiv 3 \pmod{13}$ using $\sqrt{3}=4$ sounds reasonable (defining positive as square). $(6, \pm 4)$ is on the curve.
Jan
10
reviewed Approve openssl tag wiki excerpt
Jan
10
reviewed No Action Needed Why does my SSH private key still work after changing some bytes in the file?
Jan
9
revised A simple block cipher based on the SHA-256 hash function
added 1 character in body
Jan
9
revised How can I factorize a 350 bit (106 decimal digits) number in two prime factors?
deleted 11 characters in body; edited tags; edited title
Jan
9
revised How can I factorize a 350 bit (106 decimal digits) number in two prime factors?
added 25 characters in body
Jan
6
awarded  Taxonomist
Jan
6
comment Proof that perfect privacy implies that the number of keys is at least the number of messages
You can use MathJax, which is based on LaTeX, by enclosing formulas between $ signs.
Jan
6
revised Proof that perfect privacy implies that the number of keys is at least the number of messages
deleted 35 characters in body
Jan
6
comment Is IPsec IND-CCA secure provided the used block cipher is a pseudorandom function?
But why are you mentioning CBC mode then, which is not compatible with PRFs? The proper model for a block cipher is a (strong) PRP. Since PRPs can approximate PRFs up to the birthday bound we can use PRPs even in PRF assuming modes like CTR.
Jan
6
comment Is IPsec IND-CCA secure provided the used block cipher is a pseudorandom function?
Did you mean pseudo-random-permutation?
Jan
5
revised AES Key Length vs Block Length
added 24 characters in body
Jan
5
comment Could an HMAC be used as a hash?
Related question: Why is HMAC-SHA1 still considered secure?
Jan
4
comment Importance of random number generation in Schnorr's signature
@MaartenBodewes Adam Langley patched OpenSSL to work like that since deterministic signatures would have been a breaking change.
Jan
4
comment Importance of random number generation in Schnorr's signature
If you want deterministic nonces, take a look at Ed25519 or RFC6979 - Deterministic Usage of the Digital Signature Algorithm (DSA) and Elliptic Curve Digital Signature Algorithm (ECDSA)
Jan
4
comment How does RSA compute such enormous numbers?
@smrt28 Normally the edit history would show if the post has been edited and by whom. But apparently the history has been lost due to the migration from security.se.