7,237 reputation
21142
bio website
location Netherlands
age 41
visits member for 3 years, 4 months
seen 6 hours ago

Security professional with many years of experience with the practical application of cryptographic algorithms and protocols. I'm helping with the design of protocols and API's within international standardization bodies. Lead developer of a common criteria certified product. Over 30 years of general experience with computers.


10h
comment Is it safe to encrypt random data using ECB mode?
Is there anything against using CBC and a HMAC? Why not default to security?
11h
revised Is only one shared secret generated by ECDH per key pair?
added 134 characters in body
15h
comment Is only one shared secret generated by ECDH per key pair?
The ideas for ECDH and DH are the same. ECDH has the advantage that it can use the same keys for both ECDH and ECDSA. If ECDH or ECDHE - where the last E is for ephemeral (!) - is used, look at the RFC. I would guess that ECDHE is more common and should be preferred. Note that static-static ECDH can only occur if the client authentication is enabled.
21h
answered Is only one shared secret generated by ECDH per key pair?
21h
comment What can cause similar MD5 hashes
40 bits of similarity? You could just generate oodles of hashes and order them starting from the least significant bit I suppose. But don't do it on an 8 year old laptop :P
1d
comment Using the Vigenere Cipher to find key
OK, I guess I understand the answer now, thanks for the clarification.
2d
comment Difference between the TLS cipher suites?
Often DH/DSA implementations are also constrained to relatively small key sizes. RSA implementations seem less reluctant to support larger sizes (probably because they are easier to configure - all the parameters are specific to the key and of course because most certificates use RSA).
2d
comment Can Poly1305-AES be used with AES-256?
The question is not just if it can be replaced, the question becomes if it would be any more secure if you do. It seems the polynomial was chosen to provide $2^{106}$ bits of security. Changing the underlying cipher to 256 bits keys may not provide the same level of security increase ("may" means I'm really not sure either way, but it seems to me that it won't).
Mar
28
comment Stacked LFSR - why not used?
I think LFSR's are primarily used on constrained environments, so requiring a very large state (and at least 1.25 times the processing power) is quite a big thing to ask.
Mar
28
answered Assemble RSA keys from components
Mar
28
comment Assemble RSA keys from components
I've got the strong feeling that this is still at the wrong place. It should include runtime etc. and be asked at StackOverflow.
Mar
28
awarded  Enlightened
Mar
28
awarded  Nice Answer
Mar
27
comment How efficient is the error correcting code?
Comes to that, what do you mean with efficient? Efficient compared to order, CPU time, output size, cryptographic strength, size of the acronym?
Mar
27
revised Practical brute-force attack on 128 bit encryption
added 215 characters in body
Mar
27
comment Collision attacks on digital signatures
See section 5.3: Constructing colliding certificates of "MD5 considered harmful today - Creating a rogue CA certificate"
Mar
27
revised Key sizes supported by 3DES
added 324 characters in body
Mar
27
comment Key sizes supported by 3DES
I guess I can agree on that. The keys should be indistinguishable from random for ciphers, so as long as that pre-condition is taken into account DES AAA is not triple DES. To be completely fair a check should be really present to check that situation though, otherwise the name of the algorithm would depend on the input, which is kind of weird. Or we could just stop using the frickin' 3DES algorithm of course ;)
Mar
27
revised Using the Vigenere Cipher to find key
added 169 characters in body
Mar
27
answered Using the Vigenere Cipher to find key