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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.

Currently looking for a new position in the Netherlands.


Dec
2
revised Verifying DER encoded DSA/ECDSA signature with extra content?
fleshed it out a bit
Dec
2
answered Verifying DER encoded DSA/ECDSA signature with extra content?
Dec
1
comment Definition of “pepper” in hash functions
I guess that the definition of a pepper is something that you put into a password hash function other than the salt and password. Basically I never heard of option #2, and I'm fully prepared to dismiss this idiotic idea and wipe it from memory again. If you use a "good" PBKDF function (PBKDF2, bcrypt, scrypt) it should already provide a non-random work factor (cost, iteration count), so you don't need a random pepper for that. Casino's may like the odds though :P
Dec
1
comment Rounds in cryptography
SHA-1 is broken in the academic sense as we know that the security provided is lower than the 80 bits expected from the algorithm. As yet, not a single collision has been calculated (but we're getting close). So there is a pretty big gap between broken and exploitable. MD5 does have collisions which you can create in milliseconds, but could still be used in e.g. HMAC without too much fuss (but don't).
Dec
1
revised Rounds in cryptography
added 2 characters in body
Dec
1
comment Rounds in cryptography
In other words, if the attack is of an order too large to be practical, it is only shown to be correct mathematically. If you can make it mathematically likely or provable that you require less operations than brute force to retrieve key / plaintext information then you don't actually need to perform the attack to show a block cipher is broken.
Dec
1
comment suitable programming language for cryptography algorithms
Java also has a byte type, but you cannot specify that it isn't copied to another location or that it is allocated from a specific type of memory (that e.g. isn't copied onto the disk, forgot name of file / partition :) ).
Dec
1
comment suitable programming language for cryptography algorithms
Note that Java 8 seems to extend the key and cipher interfaces to allow purging of sensitive information, but I'm not sure that already takes place.
Dec
1
answered suitable programming language for cryptography algorithms
Dec
1
comment Implementing a pseudo random function in practice
Have you tried the NIST defined PRNG's and looked for libraries implementing those?
Dec
1
comment RSA Cryptosytsem, choosing $e$
@fgrieu Should we hit the close button?
Nov
29
revised RFC 6979 - Why not simply hash the message & the private key for deterministic ECDSA?
added 62 characters in body
Nov
29
comment Corporate PKI - SHA1 deprecation
This question appears to be off-topic because it is about security, without directly involvement of crypto itself. This one is a bit tricky, the deprecation of SHA1 has obviously to do with crypto, but I think the effects and policy change are more at home on IT security
Nov
29
awarded  Yearling
Nov
28
comment Are there any standards of multi-prime RSA key generation?
I guess the answer has to be "apparently not" but that's pretty useless as an answer.
Nov
27
comment Finding Elliptical curve points and encoding text using them
Encrypting a hash sounds like ECDSA to me...
Nov
27
comment Finding Elliptical curve points and encoding text using them
Community wiki because of (2). Feel free to edit.
Nov
27
answered Finding Elliptical curve points and encoding text using them
Nov
27
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.
Nov
27
revised How to establish if a string contains a message
formatting