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location Netherlands
age 40
visits member for 3 years
seen 16 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.

On crypto I mainly answer less mathematically inclined questions, leaving security proofs to the theoretical cryptographers and analysts.


19h
comment Finding Elliptical curve points and encoding text using them
Encrypting a hash sounds like ECDSA to me...
21h
comment Finding Elliptical curve points and encoding text using them
Community wiki because of (2). Feel free to edit.
22h
comment best scheme hash function for block cipher?
You are asking a subjective question here. Define what properties you are after. Asking for "the best" of anything is begging for down votes and close votes.
22h
comment How to establish if a string contains a message
Edited question, but I don't know how to get the ~⩬ operator in TeX format, so if anybody knows how to do that, please don't hesitate.
1d
comment Using Diffie-Hellman key to establish a shared key $K_{AB}$
That's great cryptoclk, but as you can see this is a Q/A site and your Q is lacking a Q. Checking your homework is not interesting for anyone but you.
1d
comment How secure is AES-256?
I think I'm over 50 ciphersuites in my implementation (just an enum, no I'm not going to implement them all). "decrypt all standard encryption such as SSL" is in itself a wrong statement. SSL is a protocol with a large set of possible underlying algorithms.
1d
comment Using Diffie-Hellman key to establish a shared key $K_{AB}$
It's fine if you have explicit questions cryptoclk, but this Q/A site is not here to verify your homework.
1d
comment Maximum length in bits of the product n=pq
Perfect, thanks! Cannot vote up more though :)
1d
comment RSA OAEP: prevention of partial decryption of ciphertexts
Note: I've substantially edited the question above to make it at least legible. If anything is not clear, please take a look at the initial question by clicking on the time of the last edit.
1d
comment Maximum length in bits of the product n=pq
As we are clearly talking about RSA here, it would be nice to explain how $n$ is set to be exactly the key size during key pair generation - obviously that does not lead from the $pq$ calculation in itself.
1d
comment Maximum length in bits of the product n=pq
You are assuming a least significant bit of zero for two (large) prime numbers? Which one of them is even?
1d
comment Maximum length in bits of the product n=pq
Partial answer at best, there were two related questions.
1d
comment Maximum length in bits of the product n=pq
Partial answer at best, there were two related questions.
1d
comment Repeatedly using same key on different plaintexts
I've added an answer that directly addresses the question (about the key). If you don't mind I've not included the attacks on the modes of operation, those are sufficiently covered by the answers of John Meacham & DuneWalker.
1d
comment Can someone please explain to me what this means?
Closing because of the reasons given above. Probably no general answer exists, and context is lacking. It is probably easier to retrieve info elsewhere.
1d
comment CoAP authentication using DTLS
Yep, that's it.
2d
comment CoAP authentication using DTLS
Tried to explain, but without information on what precisely you don't get, it is impossible to create a better answer.
2d
comment CoAP authentication using DTLS
(including grammar mistake, I mean, "Both $K_i$ and ${nonce}_1$ are 128 bit each")
2d
comment Javascript Information Dispersal Algorithm
Well, this isn't the last word, but it should be the last word for most projects. By the way, I found a pretty serious bug when I tried the SJCL. They fixed it, but forgetting to include the AAD in the CCM calculations is pretty serious if you ask me (it's not fundamental to the problems of JavaScript though).
2d
comment Javascript Information Dispersal Algorithm
Main issue with JavaScript is that it requires TLS in yhe browser to be anywhere near secure.