2015-10-13 00:23:01 -04:00
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# Pumpkin
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A cryptographically-secure pseudo-random number generator for generating large
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prime.
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## What's up with the name?
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Since I began writing this library around Halloween of 2015, I wanted to choose
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a name that was vaguely related to the holiday. Because "pumpkin" and "prime"
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both begin with the letter 'p', I decided to use that. And that's all there
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really is to it!
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## Purpose
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`pumpkin` is a cryptographically-secure pseudo-random number generator, which is
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useful for generating large prime numbers for cryptography. In fact, `pumpkin`
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can ONLY be used to generate prime numbers. On the back-end, `pumpkin` uses the
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wonderful [ramp](https://crates.io/crates/ramp) library for storing the large
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numbers. `pumpkin` generates numbers very quickly, so you can be sure that your
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program will be performative. In our testing, primes were generated anywhere
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between 1s and 5s on average, though of course your mileage may vary.
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## Example
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2015-10-13 00:24:09 -04:00
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```rust
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2015-10-13 00:23:01 -04:00
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extern crate pumpkin;
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use pumpkin::Prime;
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fn main() {
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let p = Prime::new(2048); // Generate a new 2048-bit prime number
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let q = Prime::new(2048);
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let e = p * q;
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println("{}", e);
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/*
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* 75222035638256552797269351238215022250546763213674706... Some massive
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* 4096-bit number.
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*/
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}
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```
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## Explanation
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`Prime`s are generated much the same way that large primes are generated by
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`GnuPG`:
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1) Create a large candidate number of size based on the input given to the
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`Prime::new()` method. All `Prime`s must be at least 2-bits long (thoug it
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wouldn't make much sense to be that small.
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2) Divide the candidate number by the first 1,000 prime numbers.
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3) Test the candidate number with [Fermat's Little
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Theorem](https://www.wikiwand.com/en/Fermat's_little_theorem).
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4) Finally, run five iterations of the [Miller-Rabin Primality
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Test](https://www.wikiwand.com/en/Miller%E2%80%93Rabin_primality_test).
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`Prime`s are seeded by `rand::OsRng`, which receives its entropy via the
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operating system's own entropy source (such as `/dev/urandom`). Thus, because we
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can be confident that the generated candidate number is truly random (or as
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close to truly random as the user can hope), we don't need to do more than five
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iterations of the Miller-Rabin test to ensure primality.
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`Prime`s are simple "newtype" structs; that is, it is a tuple-like struct
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surrounding an `Int` type. `Prime`s have all of the basic algebraic and logical
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operators implemented, thus allowing you to do any operation that you would
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require.
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## Contributing
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`pumpkin` is dual-licenced under the MIT and Unlicense. Should you wish to
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contribute updates to the project, please consider signing the included `WAVER`
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file with your cryptographic digital signature (as allowed by your country's
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laws). Doing so will release your changes back into the public domain to be used
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freely by all. I did so with this project, and it would mean a lot if you did
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too!
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