owlstead

670 reputation

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	location	Netherlands
	age	39
visits	member for	1 year, 6 months
	seen	Jun 8 at 13:00
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Java and security expert with over 10 years of experience with the language and with the practical application of cryptographic protocols - including the design of protocols within international standardization bodies. Creator of a heavily used common criteria certified product. Over 30 years of experience with computers. Likes kids, cats, reading, movies and several sports.

	670 reputation	bio	website		visits	member for	1 year, 6 months
19 badges		location	Netherlands		seen	Jun 8 at 13:00

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Feb 17	answered	AES encryption with shared IV
Feb 15	comment	Extract private RSA key from USB cryptographic token using Bardou et al. attack (varian of “million message attack”) So the precise question is if this attack can be performed given a single key on a single token?
Feb 14	comment	Why is triple-DES using three different keys vulnerable to a meet-in-the-middle-attack? @CodesInChaos OK, but to make the answer complete you could maybe explain why it is possible to split triple DES with 3 keys in two halves.
Feb 14	comment	Extract private RSA key from USB cryptographic token using Bardou et al. attack (varian of “million message attack”) I've got the strong feeling that the only correct answer to this is:"depends on the token" or even better: "yes, otherwise it would not be vulnerable". But maybe somebody can give some insights into possible attack vectors and countermeasures instead.
Feb 14	comment	How to break AES CBC with PKCS#5 padding? A quick Google search already shows some results: limited-entropy.com/padding-oracle-attacks
Feb 14	comment	brute force attack on KDF vs KEY I'm not sure that the PRF within the KDF is strong enough to handle that many rounds, but I guess that's not going to be an issue :P
Feb 14	comment	Why is triple-DES using three different keys vulnerable to a meet-in-the-middle-attack? Note that the meet in the middle attack is definitely not the only reason why triple DES has lower security than you would expect by just looking at the key sizes. Check the latest NIST and ECRYPT recommendations, e.g. on keylength.com .
Feb 14	comment	How to break AES CBC with PKCS#5 padding? This answermay not be cover all attacks.
Feb 14	answered	How to break AES CBC with PKCS#5 padding?
Feb 13	comment	Is signing a hash instead of the full data considered secure? OK answer, but I would add something about the security of the used algorithms. It's possible but not advisable to hash something using SHA-1 before encrypting it with a very secure key (e.g. one created for a 521 bit NIST curve).
Feb 13	comment	PBKDF2 for key diversification @CodesInChaos me too, but most of the time AES is in hardware and SHA isn't, so you might be better off using a MAC (or actually DAC) based algorithm for smart cards, also regarding DPA attacks as fgrieu pointed out.
Feb 12	revised	Counter mode secure hash algorithm edited to reflect that Keccak is SHA-1 by now, removed last sentence about giving crypto something more challenging :)
Feb 12	awarded	Disciplined
Feb 12	revised	PBKDF2 for key diversification added 32 characters in body
Feb 12	comment	MD5 implementation Yeah, Keccak is probably a good idea, it has been designed for parallel operation (at least the primitive itself). You can try a smaller permutation for testing in a "restrained environment".
Feb 12	comment	Is AES reducible to an NP-complete problem? @CodesInChaos why not make that first remark an answer?
Feb 12	answered	PBKDF2 for key diversification
Feb 9	comment	AES implementation in java that allows key of 320-bit length If you got a key with 320 bits of entropy then you would not need a PBKDF, but a KBKDF, e.g. one of those outlined in SP 800-108 or HKDF. Using PBKDF2 would not be efficient, as it has been designed to be slow.
Feb 2	comment	Which one of the Block Cipher modes is the best? Any software implementation should now be free if not used for military purposes, and if it includes the license (check the date and item III of the last paragraph of the second license). You may notice that the date of the license has changed too.
Feb 1	comment	Which one of the Block Cipher modes is the best? OCB is now more liberally licensed, would that make it a strong contender in your opinion, Paŭlo?