Random Numbers

[Dan Honeycutt]

Hi All,

If you're in the market for a good 64 bit pseudo random number generator my post in CTF, "So. Many. Passwords." may be of interest. I'm working on an encryption application - if you know something about encryption (I don't) I'd also like to hear your comments.

Best
Dan H.

[mar]

Hi All,

If you're in the market for a good 64 bit pseudo random number generator my post in CTF, "So. Many. Passwords." may be of interest. I'm working on an encryption application - if you know something about encryption (I don't) I'd also like to hear your comments.

Best
Dan H.

Here's mine, proven to be good (real world scenarios):

Code: Select all

ULong keys[2];

inline ULong Rotate(ULong v, Byte s) {
	return &#40;v >> s&#41; | &#40;v << &#40;64-s&#41;);
&#125;

// generate next 64-bit random number
inline ULong Next64&#40;)
&#123;
	ULong tmp = keys&#91;0&#93;;
	keys&#91;0&#93; += Rotate&#40;keys&#91;1&#93; ^ 0xc5462216u ^ (&#40;ULong&#41;0xcf14f4ebu<<32&#41;, 1&#41;;
	return keys&#91;1&#93; += Rotate&#40;tmp ^ 0x75ecfc58u ^ (&#40;ULong&#41;0x9576080cu<<32&#41;, 9&#41;;
&#125;

where ULong = uint64_t
IV is two 64-bit numbers (keys) so seed with whatever you want.
If your compiler can fold rotations (last time I tried with clang it couldn't), it can generate ~1 billion 64-bit PRN per second on my several years old stock i7 quad (single core).

public domain.

Of course it's not crypto-secure so I'm not sure what you want to accomplish. Generates sequence to xor input data with? Might work as a naive encryption.

[Milos]

Hi All,

If you're in the market for a good 64 bit pseudo random number generator my post in CTF, "So. Many. Passwords." may be of interest. I'm working on an encryption application - if you know something about encryption (I don't) I'd also like to hear your comments.

https://en.wikipedia.org/wiki/Mersenne_Twister

[Dann Corbit]

http://crypto.stackexchange.com/questio ... the-output

Maybe:
http://burtleburtle.net/bob/rand/isaacafa.html

[Dan Honeycutt]

Of course it's not crypto-secure so I'm not sure what you want to accomplish. Generates sequence to xor input data with? Might work as a naive encryption.

What I'm working on is a very simple text editor with a password feature to use to store the many passwords you end up with if you are active on the internet. I'm an encryption noob, what advantage would a crypto-secure RNG give, just harder to decrypt?

Best
Dan H.

[Dan Honeycutt]

Hi All,

If you're in the market for a good 64 bit pseudo random number generator my post in CTF, "So. Many. Passwords." may be of interest. I'm working on an encryption application - if you know something about encryption (I don't) I'd also like to hear your comments.

https://en.wikipedia.org/wiki/Mersenne_Twister

I've read that Kiss is something of an improvement over the Mersenne Twister but I certainly don't know enough to attest one way or the other.

Best
Dan H.

[Dan Honeycutt]

http://crypto.stackexchange.com/questio ... the-output

Maybe:
http://burtleburtle.net/bob/rand/isaacafa.html

Thanks, Dann. I'm still trying to understand if I really need a crypto-secure RNG but if I do your second link looks like a good candidate.

Best
Dan H.

[Dann Corbit]

Of course it's not crypto-secure so I'm not sure what you want to accomplish. Generates sequence to xor input data with? Might work as a naive encryption.

What I'm working on is a very simple text editor with a password feature to use to store the many passwords you end up with if you are active on the internet. I'm an encryption noob, what advantage would a crypto-secure RNG give, just harder to decrypt?

Best
Dan H.

If you want to handle passwords, you NEED a crypto secure method.
Especially since users tend to reuse passwords.

[kbhearn]

When it comes to cryptography there's so many ways to mess it up that you really shouldn't roll your own anyways for anything other than educational purposes - take an existing crypto library, use it as intended. Even your own implementation of an accepted protocol is risky (your implementation may 'work' while not being secure against subtle attacks) - heavily used crypto libraries you at least have the peace of mind that many people are looking for and fixing these vulnerabilities.

[Lyudmil Tsvetkov]

one more thread, when one wonders, especially when posted by a mod, whether it belongs strictly here.

in any case, I see nothing related to computer chess: the use is not intended to tackle building a chess engine and, even if it were so, still the rigth forum would be the programming section.

on the other hand, I find Harvey's London chess classic thread quite acceptable, as people are using engine output to decide on a position.