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location Netherlands
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visits member for 2 years, 7 months
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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.


23h
comment Lowest number challenge scheme
@RickyDemer Huh, why? I haven't looked into the algorithm, but it seems to me that that would only be the case if the algorithms could be used to influence the other.
1d
comment Lowest number challenge scheme
From the problem indicated by Seth, there is also a link to the Socialist Millionaire problem. If you always run both of them, wouldn't you have solved the issue of equality? Or you could run the original one twice I suppose, after adding a single coin with the value of the minimal currency to one and the other. Not very efficient maybe, but it should solve the issue.
1d
comment AES CTR rekeys rapidly, does this produce patterns?
@John Upvotes are for answers you consider correct, not because you want to be socially correct.
1d
comment AES CTR rekeys rapidly, does this produce patterns?
Sorry, don't agree. The only way to answer the question is to study the generator, which is both not present in the question and the question would be too broad. Describe only the refresh function on its own, and how the input is generated for the refresh.
1d
comment Spoofing protocol nonce
Fixed my name, think your message format is better than the one I suggested (which only included minimal changes). And +1 of course.
1d
revised Spoofing protocol nonce
fixed my name, made it link to answer, which is now way way WAY down :)
Jul
20
revised KDF based on HMAC-SHA-256
added 134 characters in body
Jul
20
revised Spoofing protocol nonce
made it more clear according to comments below
Jul
20
comment Spoofing protocol nonce
Yes, I did exactly mean that.
Jul
20
revised Is it safe to seed a random number generator from system time?
changed text according to admission of author in 3rd comment
Jul
20
comment Spoofing protocol nonce
Mallory can send any nonce to either one of them, and they happily encrypt it for her in step 2. So note that the other party (Mallory in this case) is not authenticated to them in any way yet.
Jul
20
revised Video encryption at server, decryption on mobile using AES
deleted 138 characters in body
Jul
20
comment Video encryption at server, decryption on mobile using AES
This question appears to be off-topic because it is not explicitly about cryptographic algorithms, and shows insufficient research into the subject by the author.
Jul
20
revised Spoofing protocol nonce
added 98 characters in body
Jul
20
answered Spoofing protocol nonce
Jul
20
revised Spoofing protocol nonce
initial formatting; edited tags; edited tags
Jul
20
revised Decrypting an encrypted text out of order
removed a lot of text not needed for the question, removed cap. of Encryption from title
Jul
20
comment KDF based on HMAC-SHA-256
I've removed the language specific part of the answer (edited out from the question by otus). As you ask if a KDF based on HMAC-SHA-256 is identical on multiple platforms, the side question is impossible to answer. Usually crypto algorithms are identical if they 1) are based and tested against standards and 2) they apply the same encoding (if any) to the input and output.
Jul
20
revised KDF based on HMAC-SHA-256
deleted 352 characters in body
Jul
20
comment Cryptolocker 2.0 ransomed #1.23 btc
This question appears to be off-topic because it is not explicitly about cryptographic algorithms and is too broad. My commiserations to the client though.