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I'm an engineer with experience in applied cryptography, in particular in Smart Card systems.


Aug
6
comment A way around digital signatures?
Any wrong with two symmetric keys K0 K1, with K0 known to A and B only, and K1 shared between A B C; and protecting messages with two MACs with these keys, except when originating from C which uses K1 only?
Aug
2
revised Is perfect-forward secrecy achieved with RSA?
Incorporate some of CodesInChaos's comment
Aug
1
revised Is perfect-forward secrecy achieved with RSA?
Mention the public key used to verify the signature
Aug
1
revised Is perfect-forward secrecy achieved with RSA?
Polish
Aug
1
revised Is perfect-forward secrecy achieved with RSA?
start from general and apply to RSA
Aug
1
answered Is perfect-forward secrecy achieved with RSA?
Aug
1
comment Reasons for Chinese SM2 Digital Signature Algorithm
Part 1 (out of 4) of the 2010 Chinese standard defining SM2 algorithms is published here, and some of it is understandable when automatically translated. $\;$ Could no find part 2 on SM2 signature. $\;$ Jing Xu & Dengguo Feng's Comments on the SM2 Key Exchange Protocol is a claimed attack on part 3.
Jul
31
revised Rainbow table for DES with all-zero plaintext?
Use m rather than k as the width of the input of F, to avoid conflict with answers using k for another purpose
Jul
31
comment Rainbow table for DES with all-zero plaintext?
You are considering $k$ chains of length $k$; why are these parameters taken to be the same? Is it next to optimum? $\;$ Also: is the distinguished point technique useful with rainbow tables?
Jul
31
comment How can rainbow tables be used for a dictionary attack?
Welcome to CSE! I see no fundamental confusion in the question, where it is asked if NTLM passwords are hashed; which you answer by the negative. $\;$ Note: I took the liberty to embed the links, including the one you struggled with. This is conveniently done with the Hyperlink button of the edit window, or Ctrl-L; also, <a>http://foo.bar</a> or [text](http://foo.bar) works (the later is usable in comments too). While editing an answer, the preview let you see what it will look like, including hyperlinks.
Jul
31
revised How can rainbow tables be used for a dictionary attack?
Embed links
Jul
30
awarded  Nice Question
Jul
29
comment Rainbow table for DES with all-zero plaintext?
I read there are two canonical improvements to that: $\;$ 1) Rivest's distinguished points, iterating encrypt-then-truncate starting from a point in some subset of the keyspace (e.g. with some 16 bits at zero) until reaching such subset, for a modest but welcome reduction in memory requirement; and $\;$ 2) rainbow tables, which seem to originate in: Philippe Oechslin's Making a Faster Cryptanalytic Time-Memory Trade-Off, in proceedings of Crypto 2003.
Jul
29
comment Rainbow table for DES with all-zero plaintext?
M. E. Hellman, A Cryptanalytic Time-Memory Tradeoff, IEEE Trans. on Info. Theory, Vol. 26, July 1980, pp. 401-406. $\;$ At least that one is relatively straightforward! It does not use what otus's answer and comment describes as the rainbow improvement, and I wonder how much that improves the time-memory tradeoff.
Jul
28
comment Rainbow table for DES with all-zero plaintext?
In addition of things I do not grasp with rainbow tables (see updated question): why the $\oplus i$ term?
Jul
28
revised Rainbow table for DES with all-zero plaintext?
Addition stating my ignorance
Jul
28
comment Understanding Lattice based cryptosystem
@pushpen.paul: It seems that the Wikipedia entry, or/and for this or that example it cites, is enough to answer what makes lattice based system strong? with: for many, the hardness of the Closest Vector Problem in some appropriate lattice. Perhaps, state this and ask for more, e.g. what the CVP is, or why it is believed to be secure even with quantum computers?
Jul
28
comment Compression function to guarantee randomness of one time pads?
A bziped file starts 42h 5Ah; not good for a keystream! There are a lot of other redundancy, including markers of compression settings, and at least one error detection code. More generally, for many existing compression algorithms, the output is distinguishable from random even if the input is not; often, the distinguisher can simply be: decompresses without error.
Jul
26
revised Rainbow tables and blowfish
Add rainbow-table tag
Jul
25
revised Idea for user/pass hashing to prevent rainbow tables, would it work?
Add rainbow-table tag