Reputation
14,113
Next tag badge:
129/100 score
18/20 answers
Badges
3 37 75
Newest
 Yearling
Impact
~355k people reached

Nov
9
comment Encrypting and obscuring data between site/user without SSL
Also, if the client JavaScript comes from the server over a non-authorized connection, there is no way to be sure that it hasn't been meddled with by the attacker, which makes all the secure protocols moot. See Javascript Cryptography Considered Harmful.
Nov
9
comment Encrypting and obscuring data between site/user without SSL
What kind of "environment" is there which doesn't support SSL, but does support other kinds of encryption? Do you have filters which block SSL, or is your hardware not good enough to handle the crypto?
Nov
9
comment Is it reasonable to assure that p-1 and q-1 aren't smooth?
@fgrieu, Thomas: What about choosing first a random big prime number $x$, then random (even) factors $y$ until $x·y + 1$ hits a prime number (and then take this as $p$ or $q$)? Or use the version which Henno proposed?
Nov
8
comment Encrypting (CBC) identical files with same key and different iv, is it less secure?
As long as your N times the size of your file remains small compared to the $2^{68}$ bytes I mentioned in the last paragraph, the chance to get anything out of the ciphertext remains negligible.
Nov
8
answered Encrypting (CBC) identical files with same key and different iv, is it less secure?
Nov
8
revised How to choose constants in a cryptographic function?
edited tags
Nov
7
revised What is the purpose of four different secrets shared by client and server in SSL/TLS?
better title, formatting/rewording, tags
Nov
7
comment How to choose constants in a cryptographic function?
It does contain this paragraph: The above particular values of opad and ipad were chosen to have a very simple representation (to simplify the function's specification and minimize the potential of implementation errors), and to provide a high Hamming distance between the pads. The latter is intended to exploit the mixing properties attributed to the compression function underlying the hash schemes in use. These properties are important in order to provide computational independence between the two derived keys.
Nov
7
comment How to choose constants in a cryptographic function?
Looking at Keying hash functions for message authentication, which seems to be a fuller version of a paper which appeared in Crypto 96, there is no Lemma 5.2 (though section 5.2 is "Security of HMAC"). It doesn't contain any "rka-advantage".
Nov
7
comment How to choose constants in a cryptographic function?
@Henno: Do you have some link for the HMAC-proof? I had a look at New Proofs for NMAC and HMAC: Security without Collision-Resistance, but this proof seems to work with any values of ipad and opad.
Nov
7
revised How to choose constants in a cryptographic function?
add HMAC, some links, put nothing-up-my-sleeve in front.
Nov
6
answered How to choose constants in a cryptographic function?
Nov
6
wiki created diffie-hellman description
Nov
6
wiki created diffie-hellman excerpt
Nov
6
wiki created xor description
Nov
6
wiki created xor excerpt
Nov
5
wiki created initialization-vector description
Nov
5
wiki created initialization-vector excerpt
Nov
5
comment Can CBC ciphertext be decrypted if the key is known, but the IV not?
Welcome to Cryptography Stack Exchange. I changed the title and tags a bit, as your question (and the answer) actually applies to all block ciphers when used with CBC, not only AES.
Nov
5
revised Can CBC ciphertext be decrypted if the key is known, but the IV not?
better title, some rewording, add CBC-information, add tags.; edited tags; edited tags; edited tags