Reputation
12,269
Next tag badge:
90/100 score
20/20 answers
Badges
1 31 61
Newest
 Enlightened
Impact
~211k people reached

Jun
30
awarded  Outspoken
Jun
30
comment Double the key in block cipher - which approach is better?
@nopenope If you look at the decryption operation $D^\prime_2$ instead of the decryption operation, you get the same formula as for for $E^\prime_1$, except that $c$ and $m$ are swapped. Since an attacker knows both $m$ and $c$, they don't care if they're attacking $E^\prime_1$ or $D^\prime_2$.
Jun
30
revised Double the key in block cipher - which approach is better?
added 197 characters in body
Jun
30
answered EdDSA Signature Algorithm - hash of secret key
Jun
30
comment Ideas for non duplicate cryptographically secure numbers
If 64 bit values are fine, you could encrypt a counteer using a 64 bit blockcipher, like blowfish or 3DES.
Jun
29
revised Double the key in block cipher - which approach is better?
added 121 characters in body
Jun
29
revised Double the key in block cipher - which approach is better?
added 121 characters in body
Jun
29
answered Double the key in block cipher - which approach is better?
Jun
29
comment Double the key in block cipher - which approach is better?
Xoring $k_2$ into both then plaintext and the ciphertext is better that xoring it only into one Even Mansour construction
Jun
29
revised Understanding elliptic curve encryption
added 39 characters in body; edited tags
Jun
29
comment Security of this deterministic encryption scheme
Implementing this scheme without a padding oracle isn't trivial, unless the MACed plaintext is already padded.
Jun
29
answered Adding tweak to a block cipher
Jun
29
comment Extracting a WinRAR password
I can't say for sure without having looked at the winrar crypto in detail, but I consider it pretty unlikely since it'd require an unusually dumb mistake. Probably the best you can do is running a program that tests many password candidates, but that's only feasible for simple passwords.
Jun
29
comment Extracting a WinRAR password
Known plaintext attacks don't work against modern ciphers.
Jun
29
comment Block Ciphers - Standardize plain text
@AlexRibeiro CTR produces the key stream by encrypting a sequence of counters. While you compute a key stream consisting of full blocks, you can simply discard the useless final bytes. CTR can do that, since it doesn't pass the ciphertext blocks to the blockcipher when decrypting, instead passing the same counters as when encrypting.
Jun
29
answered Forgery attack on OCB
Jun
29
reviewed Looks OK Forgery attack on OCB
Jun
29
reviewed No Action Needed HMAC-SHA1( secret key ) with header of a transmitted file
Jun
29
comment Bouncy Castle and Salsa 20
I'm voting to close this question as off-topic because it is a programming problem, not a cryptography problem.
Jun
29
comment How does bitmessage encryption work?
Since somebody creating two public keys with the same address doesn't look like a relevant attack, this only relies on (multi-target) second pre-image resistance, not collision resistance. 160 bits is plenty for that.