Tag Info

Hot answers tagged

6

OpenPGP as defined by RFC 4880 knows two different encodings. Binary encoding Obviously, there is no reasonable limitation to an (ASCII) character subset in binary encoding. Radix 64 Radix 64 is also often entitled ASCII armored. In the end, it is a base64 encoding with a checksum. The content may consist of [a-zA-Y0-0+/=]. ASCII-armored OpenPGP ...


4

It mainly depends on how the algorithm was selected. If it was selected by a public competition like for AES, then it is likely to be secure. If it was forced in by the NSA such as Dual-EC random number generator, then you may have some doubts. Other questions you may want to ask yourself are: Is this an "original" algorithm or was the problem that it ...


3

In general, no. There are: $$ {2^{64} \choose 2^n} = \frac{2^{64}!}{2^{n}!(2^{64}-2^n)!} $$ possible ways of selecting $2^n$ distinct 64-bit vectors. This is a huge number; using Stirling's approximation of factorials, when $2^{n}$ is substantially smaller than $2^{64}$ (i.e. when $n$ is smaller than $55$ or so), this number of combinations is approximately ...


3

This sounds like "fair exchange," the subject of many good research papers. In general you need a third party to give any security guarantees, but "optimistic fair exchange" involves the third party only when one of the parties tries to cheat (i.e., when both play honestly there is no involvement from the third party). Incidentally, Diffie-Hellman is most ...


1

Sketch. Suppose you have an adversary against the composed scheme with advantage $\epsilon_3$. Observe that whenever you have a signature for the composed system, you have a signature for each of the three component signature schemes. It should then follow that a forger for the composed signature scheme can be turned into a forger for each of the three ...


1

I believe this can be reduced to a case of format-preserving encryption. http://en.m.wikipedia.org/wiki/Format-preserving_encryption Using one of the many algorithms for FPE, you should be able to do such a mapping. EDIT: As Seth points out in the comments to my original answer, the "cycling" method of FPE doesn't work here, but the first method described ...


1

Related to Curve25519 Curve25519 seems to be secure so far. Yet, you have to remind yourself that Dr. Bernstein specified Curve25519 for key-exchange. Meaning: key-generation, transaction signing, and verification are somewhat different beasts – you might want to cross-check on that before jumping toward Curve25519. Sure, Curve25519-java supports signing… ...


1

There are good reasons to think an algorithm being in Suite B is evidence NSA thinks it's secure (they are used to protect classified materials). There are also reasons to think algorithms they recommend for others may not be (it's happened before). So I don't think you can objectively say much about an algorithm either way just on the basis of whether it's ...


1

There is some confusion in your question, because a signature in a public key cryptosystem is (usually) not just a hash, but a hash of the message that is signed using the private key. E.g. in RSA it would be a hash value padded and raised to the private exponent. There are two ways to have an authenticated encryption in a public key system: Should we ...



Only top voted, non community-wiki answers of a minimum length are eligible