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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.


15h
awarded  Strunk & White
15h
revised pbkdf wiki description
key strengthening -> key stretching; added 27 characters in body
15h
revised pbkdf wiki excerpt
key strengthening -> key stretching; deleted 260 characters in body
15h
awarded  Tag Editor
15h
wiki created pbkdf description
15h
wiki created pbkdf excerpt
15h
revised Is this a plausible PBKDF?
edited tags; edited tags
16h
comment ECC cryptography with shorter signature when not needing high security?
Have you ever calculated e.g. $2^{43}$? If you have a million years and you divide by that number, then there is not much left. You are simply using too few bits for ECDSA.
20h
comment ECC cryptography with shorter signature when not needing high security?
The time to break the crypto goes down exponentially with the bitsize. Currently the shortest ECC keys are about 192 for secure applications, but say we use 160 bit ECC keys for lower security. Then your key has about 160 - 73 = 87 bits less security. Does your attacker actually have $2^{87}$ less time to crack it? Note that this is assuming that the signature is the same size as the key size; in practice it is about twice that size. Note that with ECC it could actually be $2^{87/2}$ less time, but that would still be a huge number).
1d
comment GPG & Mcrypt - difference?
Either one of them is OK. If you want to improve security, I would rather focus on key management and adding - for instance - an authentication tag over the ciphertext.
1d
comment Recover plaintext from truncated ciphertext using AES for FPE
I've removed the Java code from the comments, showing how to perform ECB mode of encryption is not really useful.
1d
revised Recover plaintext from truncated ciphertext using AES for FPE
deleted 516 characters in body
1d
comment GPG & Mcrypt - difference?
Mainly my work focusses on AES (in all it's forms) and 3DES. Unfortunately I therefore don't know much about CAST. Serpent has a good rep. though (as does AES, of course).
2d
revised A patched SHA1 attempt for password verification
edited tags; edited title
2d
comment Design of S box
It may be that this question is overly broad; it more or less includes the whole domain of designing and analyzing a block cipher.
2d
comment A patched SHA1 attempt for password verification
"There is just only one thing which bothers us": hire a good security consultant and given your scheme, there will be a lot more bothering you.
2d
comment Encryption method with master key and user keys
Sorry, data flow/sequence diagrams were not enabled in the web based software :)
2d
comment GPG & Mcrypt - difference?
Certainly, you should in that case preferably use the EVP_ "higher" level API of OpenSSL.
2d
answered Encryption method with master key and user keys
2d
comment Entropy Loss of KDFs
Well, it was "for example" :P Besides the pun, lets not specialize answers too much. Thanks for the edit, had already voted up...