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location Netherlands
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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.


Jul
14
revised Could I use an hashing function for Symmetric encryption?
deleted 4 characters in body
Jul
14
comment Could I use an hashing function for Symmetric encryption?
@otus To be fair, my initial scan did not identify the main issue either. But we're already up to 4 security related issues now.
Jul
14
revised Could I use an hashing function for Symmetric encryption?
added 268 characters in body
Jul
14
comment Could I use an hashing function for Symmetric encryption?
Yup, that's it. You should also look at Password Based Key Derivation Functions instead of performing hash(password). As you may have noticed, you should only use your scheme for practicing crypto.
Jul
14
comment Could I use an hashing function for Symmetric encryption?
Right. What if you have three plaintexts, "Yes", "Yes" and "No" and send them over a line? What if you send a credit card number for which only 4 digits are unknown?
Jul
14
comment Could I use an hashing function for Symmetric encryption?
@otus I'm not sure we have to close this question though as it describes a different algorithm than the question you pointed to. We can hack this particular one apart in our answers here. How useful that is remains questionable, I admit.
Jul
14
answered Could I use an hashing function for Symmetric encryption?
Jul
14
revised Does CCA security imply authenticated encryption?
will -> should, I wish every implementation would do that, but alas...
Jul
13
comment Getting 88bytes cipher output from 48bytes input in AES
Removed first comment because it went beyond calling the paper poor. The advice about not using the paper stands of course.
Jul
13
accepted RSA key pair generation using PRNG with same seed
Jul
13
comment Clarification of the terms “brute force” and “guess”
I'm thinking that it has to do with being polynomially bounded which means many keys are not valid in the first place. Of course, an adversary is not going to choose invalid keys. So you need some other method to define security - the notion of a brute force attack doesn't hold anymore. Think of brute force as infinitely dumb, just iterating through every possible (bit) value. Even a dictionary attack is not brute force.
Jul
13
revised Effective security of block cipher – equal the key size, or half the key size?
deleted 4 characters in body
Jul
13
comment How do I decide what mode to use?
Anything missing from my answer, Stéphane?
Jul
13
revised Effective security of block cipher – equal the key size, or half the key size?
k -> k -1 ... averaging here
Jul
13
comment Does CCA security imply authenticated encryption?
I'm assuming a block cipher here.
Jul
13
answered Does CCA security imply authenticated encryption?
Jul
5
comment Getting 88bytes cipher output from 48bytes input in AES
OK, looked into it. This was a paper to get their Bachelors degree. If that is the level of education on the Mumbai university, I will put question marks on any students that graduated over there. I wonder why they let them put this online, even the spelling is horrible - although from a science point of view, that may be the least of their worries. Then again, this is from students, not full blown cryptographers.
Jul
3
comment Types of cryptography
@CodesInChaos The usual comment :)
Jul
2
awarded  Curious
Jul
2
comment RSA 896 vs 1024 vs 2048 in Javascript?
@NDF1 That's correct. But to understand what that means you should understand what "unsafe" means on that website. And you probably have to understand Bernstein as well. "Unsafe" on that website does not mean "broken". You should however validate public keys for BrainpoolP256r1.