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seen Mar 23 at 10:08

Mar
23
comment Export from US of crypto software with key-size > 56 bits still needs permission?
Is it really the case that open-source and free-of-charge alone will exempt from Wassenaar's requirements? I have the same doubts as rath. Could you be kind enough to cite the relevent passages or section numbers of the Wassenaar document?
Mar
20
comment Security of Deterministic Encryption Scheme
@sashank: The link I cited was intended for you to get some useful informations via comparing deterministic with probabilistic (non-deterministic) encryptions. You may also look at Wikipedia's article on deterministic encryption.
Mar
20
comment Security of Deterministic Encryption Scheme
See en.wikipedia.org/wiki/Probabilistic_encryption
Mar
20
revised Export from US of crypto software with key-size > 56 bits still needs permission?
added 5 characters in body
Mar
20
revised Export from US of crypto software with key-size > 56 bits still needs permission?
deleted 3 characters in body
Mar
20
answered Export from US of crypto software with key-size > 56 bits still needs permission?
Mar
18
comment Export from US of crypto software with key-size > 56 bits still needs permission?
But publishing on the Internet is export to the entire world, including the couple of blacklisted states, isn't it?
Mar
18
comment Export from US of crypto software with key-size > 56 bits still needs permission?
Do I understand you correctly that "strictly" speaking an approval would be needed but "defacto" the authority tolerates the online publications? (I just want to be 100% sure of having correctly understood the issue.)
Mar
17
asked Export from US of crypto software with key-size > 56 bits still needs permission?
Mar
3
comment How to solve the reverse of an equation that uses MOD?
@hsikcah: You have r=83172, b=3182, a=380951. b**(a-2)=62135 mod a. So v=r*62135=291905 mod a, and v*b=83172=r mod a, as required.
Mar
2
comment Are there any practical implementation of a homomorphic hashing or signature scheme?
@sashank: Note though that I had responded to your original (unedited) OP with a comment and given there a negative answer.
Feb
27
comment Are there any practical implementation of a homomorphic hashing or signature scheme?
As far as I know, there is yet no practically efficient implementation of fully homomorphic encryption on the horizon. So the answer to your question would evidently be negative, at least for a good hashing scheme, IMHO.
Feb
10
comment Can we replace the XOR operation in DES with some other operation?
If xor is used somewhere in encryption, that effect is reversed in decryption with xor. Similarly addition mod 2n can be reversed with subtraction mod 2n. So you could use instead of xor the modular addition. But the result isn't DES and I don't know what severe adverse effects one obtains with that kind of modification to DES.
Feb
10
asked Any historical accounts of cryptanalysis of Jefferson's wheel cipher?
Feb
6
comment How to check the strength of an encryption algorithm?
See en.wikipedia.org/wiki/Differential_cryptanalysis for the important role played by S-Boxes in DES. In fact the other components are comparatively unessential. In comparison, in AES there are other components that are also essential IMHO.
Feb
6
comment How to check the strength of an encryption algorithm?
@PaĆ­loEbermann: There have been huge numbers of scientific papers on the security properties of certain S-Boxes, e.g. of DES. So that's "something whose security properties we use when proving properties of higher-level algorithms [here DES]", right? Hence S-Box is a primitive according to your own definition.
Feb
5
comment How to check the strength of an encryption algorithm?
@CodesInChaos: Do you imply that an S-Box isn't a primitive of ciphers? What's your general definition of primitives of ciphers?
Feb
5
comment How to check the strength of an encryption algorithm?
@CodesInChaos: Commonly a new algorithm wouldn't likely contain brand-new (invented) primitives but is simply some "presumably" new (advantageous) way of employing (arranging) certain already known types of primitives e.g. S-boxs etc. If one posts such algorithms, could that be on-topic?
Feb
5
comment Source for examples with broken cryptography
NSA had designed an algorithm on which an attack was found only hours after its declassification. See en.wikipedia.org/wiki/Skipjack_%28cipher%29
Feb
5
comment How to check the strength of an encryption algorithm?
I doubt that it conforms to the general guiding principles of this forum that one posts a particular algorithm and asks how to check whether it is secure enough or not. Could someone clarify that issue?