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7

Adding characters to an existing password in such a fixed and known way does not alter its entropy as long as everything else remains the same. In your specific case, adding a space every four characters can be seen as purely formatting to make passwords more readable. Should an attacker not know about the formatting, the password just became six characters ...


1

I know you said that "without having to all sync up with each other" but other people mentioned the blockchain so I wanted to mention a cool paper I read: https://jbonneau.com/doc/BGB17-IEEESB-proof_of_delay_ethereum.pdf This paper solves problems with using block hashes as randomness. If you simply use the block hash as your randomness source, you ...


4

A possibility is to rely on jointly observable, untemperable and apparently random, physical processes. There is one such phenomenon which is very commonly mentioned in the cryptographic community, though this is more as an indication of feasibility than as a concrete and well-fleshed proposal: extracting common randomness from the dark spots of the sun. ...


2

I'd suggest taking a look at the Truestamp Observable Entropy project. We recently created this to address a need for the type of randomness you're asking about. Observable Entropy automatically collects randomness from publicly verifiable sources every five minutes, storing and hashing the contents of that retrieved data. The hash of each data source file ...


2

The exact official trade price of a publicly traded stock at a given time is very expensive to control: throwing a lot of money at it will definitely let you influence it, but not control all the digits. Average over multiple stocks and you get a value that's public and effectively impossible to fully control or predict. Of course there's significant bias in ...


1

Converting an arbitrary message into a pseudo random number is essentially computing a cryptographic hash. So this question seems to be asking what is the fastest secure cryptographic hash? It is unclear what are the security requirements you have for this hash, some algorithms are very simple and have are not cryptographically secure but still provide ...


0

Warning: I'm a newbie TL;DR. The fastest pre-shared key encryption algorithm, contains the fastest CSPRNG (it just adds that it XORs input against it). You may want to only modify one such that it ignores the input (e.g. doesn't XOR against the input because we don't want to encrypt). Assuming you ask about cryptographically secure PRNGs: If you want ...


3

And from a security standpoint, incrementing randomness should not make a difference.. There are two reasons to 'go back' rather than do some special logic. The first reason is to reduce the amount of 'hard-to-test' special purpose code. Any way of 'incrementing $k$' would involve code that is extremely rarely run (and for which it would be hard to devise ...


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