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authorDaniel Mueller <deso@posteo.net>2019-01-02 21:14:10 -0800
committerDaniel Mueller <deso@posteo.net>2019-01-02 21:14:10 -0800
commitecf3474223ca3d16a10f12dc2272e3b0ed72c1bb (patch)
tree03134a683791176b49ef5c92e8d6acd24c3b5a9b /rand/rand_core/src/lib.rs
parent686f61b75055ecb02baf9d9449525ae447a3bed1 (diff)
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Update nitrokey crate to 0.2.3
This change updates the nitrokey crate to version 0.2.3. This version bumps the rand crate used to 0.6.1, which in turn requires an additional set of dependencies. Import subrepo nitrokey/:nitrokey at b3e2adc5bb1300441ca74cc7672617c042f3ea31 Import subrepo rand/:rand at 73613ff903512e9503e41cc8ba9eae76269dc598 Import subrepo rustc_version/:rustc_version at 0294f2ba2018bf7be672abd53db351ce5055fa02 Import subrepo semver-parser/:semver-parser at 750da9b11a04125231b1fb293866ca036845acee Import subrepo semver/:semver at 5eb6db94fa03f4d5c64a625a56188f496be47598
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+// Copyright 2018 Developers of the Rand project.
+// Copyright 2017-2018 The Rust Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Random number generation traits
+//!
+//! This crate is mainly of interest to crates publishing implementations of
+//! [`RngCore`]. Other users are encouraged to use the [rand] crate instead
+//! which re-exports the main traits and error types.
+//!
+//! [`RngCore`] is the core trait implemented by algorithmic pseudo-random number
+//! generators and external random-number sources.
+//!
+//! [`SeedableRng`] is an extension trait for construction from fixed seeds and
+//! other random number generators.
+//!
+//! [`Error`] is provided for error-handling. It is safe to use in `no_std`
+//! environments.
+//!
+//! The [`impls`] and [`le`] sub-modules include a few small functions to assist
+//! implementation of [`RngCore`].
+//!
+//! [rand]: https://crates.io/crates/rand
+//! [`RngCore`]: trait.RngCore.html
+//! [`SeedableRng`]: trait.SeedableRng.html
+//! [`Error`]: struct.Error.html
+//! [`impls`]: impls/index.html
+//! [`le`]: le/index.html
+
+#![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk.png",
+ html_favicon_url = "https://www.rust-lang.org/favicon.ico",
+ html_root_url = "https://rust-random.github.io/rand/")]
+
+#![deny(missing_docs)]
+#![deny(missing_debug_implementations)]
+#![doc(test(attr(allow(unused_variables), deny(warnings))))]
+
+#![cfg_attr(not(feature="std"), no_std)]
+#![cfg_attr(all(feature="alloc", not(feature="std")), feature(alloc))]
+
+#[cfg(feature="std")] extern crate core;
+#[cfg(all(feature = "alloc", not(feature="std")))] extern crate alloc;
+#[cfg(feature="serde1")] extern crate serde;
+#[cfg(feature="serde1")] #[macro_use] extern crate serde_derive;
+
+
+use core::default::Default;
+use core::convert::AsMut;
+use core::ptr::copy_nonoverlapping;
+
+#[cfg(all(feature="alloc", not(feature="std")))] use alloc::boxed::Box;
+
+pub use error::{ErrorKind, Error};
+
+
+mod error;
+pub mod block;
+pub mod impls;
+pub mod le;
+
+
+/// The core of a random number generator.
+///
+/// This trait encapsulates the low-level functionality common to all
+/// generators, and is the "back end", to be implemented by generators.
+/// End users should normally use [`Rng`] from the [rand] crate, which is
+/// automatically implemented for every type implementing `RngCore`.
+///
+/// Three different methods for generating random data are provided since the
+/// optimal implementation of each is dependent on the type of generator. There
+/// is no required relationship between the output of each; e.g. many
+/// implementations of [`fill_bytes`] consume a whole number of `u32` or `u64`
+/// values and drop any remaining unused bytes.
+///
+/// The [`try_fill_bytes`] method is a variant of [`fill_bytes`] allowing error
+/// handling; it is not deemed sufficiently useful to add equivalents for
+/// [`next_u32`] or [`next_u64`] since the latter methods are almost always used
+/// with algorithmic generators (PRNGs), which are normally infallible.
+///
+/// Algorithmic generators implementing [`SeedableRng`] should normally have
+/// *portable, reproducible* output, i.e. fix Endianness when converting values
+/// to avoid platform differences, and avoid making any changes which affect
+/// output (except by communicating that the release has breaking changes).
+///
+/// Typically implementators will implement only one of the methods available
+/// in this trait directly, then use the helper functions from the
+/// [`rand_core::impls`] module to implement the other methods.
+///
+/// It is recommended that implementations also implement:
+///
+/// - `Debug` with a custom implementation which *does not* print any internal
+/// state (at least, [`CryptoRng`]s should not risk leaking state through
+/// `Debug`).
+/// - `Serialize` and `Deserialize` (from Serde), preferably making Serde
+/// support optional at the crate level in PRNG libs.
+/// - `Clone`, if possible.
+/// - *never* implement `Copy` (accidental copies may cause repeated values).
+/// - *do not* implement `Default` for pseudorandom generators, but instead
+/// implement [`SeedableRng`], to guide users towards proper seeding.
+/// External / hardware RNGs can choose to implement `Default`.
+/// - `Eq` and `PartialEq` could be implemented, but are probably not useful.
+///
+/// # Example
+///
+/// A simple example, obviously not generating very *random* output:
+///
+/// ```
+/// #![allow(dead_code)]
+/// use rand_core::{RngCore, Error, impls};
+///
+/// struct CountingRng(u64);
+///
+/// impl RngCore for CountingRng {
+/// fn next_u32(&mut self) -> u32 {
+/// self.next_u64() as u32
+/// }
+///
+/// fn next_u64(&mut self) -> u64 {
+/// self.0 += 1;
+/// self.0
+/// }
+///
+/// fn fill_bytes(&mut self, dest: &mut [u8]) {
+/// impls::fill_bytes_via_next(self, dest)
+/// }
+///
+/// fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
+/// Ok(self.fill_bytes(dest))
+/// }
+/// }
+/// ```
+///
+/// [rand]: https://crates.io/crates/rand
+/// [`Rng`]: ../rand/trait.Rng.html
+/// [`SeedableRng`]: trait.SeedableRng.html
+/// [`rand_core::impls`]: ../rand_core/impls/index.html
+/// [`try_fill_bytes`]: trait.RngCore.html#tymethod.try_fill_bytes
+/// [`fill_bytes`]: trait.RngCore.html#tymethod.fill_bytes
+/// [`next_u32`]: trait.RngCore.html#tymethod.next_u32
+/// [`next_u64`]: trait.RngCore.html#tymethod.next_u64
+/// [`CryptoRng`]: trait.CryptoRng.html
+pub trait RngCore {
+ /// Return the next random `u32`.
+ ///
+ /// RNGs must implement at least one method from this trait directly. In
+ /// the case this method is not implemented directly, it can be implemented
+ /// using `self.next_u64() as u32` or
+ /// [via `fill_bytes`](../rand_core/impls/fn.next_u32_via_fill.html).
+ fn next_u32(&mut self) -> u32;
+
+ /// Return the next random `u64`.
+ ///
+ /// RNGs must implement at least one method from this trait directly. In
+ /// the case this method is not implemented directly, it can be implemented
+ /// [via `next_u32`](../rand_core/impls/fn.next_u64_via_u32.html) or
+ /// [via `fill_bytes`](../rand_core/impls/fn.next_u64_via_fill.html).
+ fn next_u64(&mut self) -> u64;
+
+ /// Fill `dest` with random data.
+ ///
+ /// RNGs must implement at least one method from this trait directly. In
+ /// the case this method is not implemented directly, it can be implemented
+ /// [via `next_u*`](../rand_core/impls/fn.fill_bytes_via_next.html) or
+ /// via `try_fill_bytes`; if this generator can fail the implementation
+ /// must choose how best to handle errors here (e.g. panic with a
+ /// descriptive message or log a warning and retry a few times).
+ ///
+ /// This method should guarantee that `dest` is entirely filled
+ /// with new data, and may panic if this is impossible
+ /// (e.g. reading past the end of a file that is being used as the
+ /// source of randomness).
+ fn fill_bytes(&mut self, dest: &mut [u8]);
+
+ /// Fill `dest` entirely with random data.
+ ///
+ /// This is the only method which allows an RNG to report errors while
+ /// generating random data thus making this the primary method implemented
+ /// by external (true) RNGs (e.g. `OsRng`) which can fail. It may be used
+ /// directly to generate keys and to seed (infallible) PRNGs.
+ ///
+ /// Other than error handling, this method is identical to [`fill_bytes`];
+ /// thus this may be implemented using `Ok(self.fill_bytes(dest))` or
+ /// `fill_bytes` may be implemented with
+ /// `self.try_fill_bytes(dest).unwrap()` or more specific error handling.
+ ///
+ /// [`fill_bytes`]: trait.RngCore.html#method.fill_bytes
+ fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>;
+}
+
+/// A marker trait used to indicate that an [`RngCore`] or [`BlockRngCore`]
+/// implementation is supposed to be cryptographically secure.
+///
+/// *Cryptographically secure generators*, also known as *CSPRNGs*, should
+/// satisfy an additional properties over other generators: given the first
+/// *k* bits of an algorithm's output
+/// sequence, it should not be possible using polynomial-time algorithms to
+/// predict the next bit with probability significantly greater than 50%.
+///
+/// Some generators may satisfy an additional property, however this is not
+/// required by this trait: if the CSPRNG's state is revealed, it should not be
+/// computationally-feasible to reconstruct output prior to this. Some other
+/// generators allow backwards-computation and are consided *reversible*.
+///
+/// Note that this trait is provided for guidance only and cannot guarantee
+/// suitability for cryptographic applications. In general it should only be
+/// implemented for well-reviewed code implementing well-regarded algorithms.
+///
+/// Note also that use of a `CryptoRng` does not protect against other
+/// weaknesses such as seeding from a weak entropy source or leaking state.
+///
+/// [`RngCore`]: trait.RngCore.html
+/// [`BlockRngCore`]: ../rand_core/block/trait.BlockRngCore.html
+pub trait CryptoRng {}
+
+/// A random number generator that can be explicitly seeded.
+///
+/// This trait encapsulates the low-level functionality common to all
+/// pseudo-random number generators (PRNGs, or algorithmic generators).
+///
+/// The [`rand::FromEntropy`] trait is automatically implemented for every type
+/// implementing `SeedableRng`, providing a convenient `from_entropy()`
+/// constructor.
+///
+/// [`rand::FromEntropy`]: ../rand/trait.FromEntropy.html
+pub trait SeedableRng: Sized {
+ /// Seed type, which is restricted to types mutably-dereferencable as `u8`
+ /// arrays (we recommend `[u8; N]` for some `N`).
+ ///
+ /// It is recommended to seed PRNGs with a seed of at least circa 100 bits,
+ /// which means an array of `[u8; 12]` or greater to avoid picking RNGs with
+ /// partially overlapping periods.
+ ///
+ /// For cryptographic RNG's a seed of 256 bits is recommended, `[u8; 32]`.
+ ///
+ ///
+ /// # Implementing `SeedableRng` for RNGs with large seeds
+ ///
+ /// Note that the required traits `core::default::Default` and
+ /// `core::convert::AsMut<u8>` are not implemented for large arrays
+ /// `[u8; N]` with `N` > 32. To be able to implement the traits required by
+ /// `SeedableRng` for RNGs with such large seeds, the newtype pattern can be
+ /// used:
+ ///
+ /// ```
+ /// use rand_core::SeedableRng;
+ ///
+ /// const N: usize = 64;
+ /// pub struct MyRngSeed(pub [u8; N]);
+ /// pub struct MyRng(MyRngSeed);
+ ///
+ /// impl Default for MyRngSeed {
+ /// fn default() -> MyRngSeed {
+ /// MyRngSeed([0; N])
+ /// }
+ /// }
+ ///
+ /// impl AsMut<[u8]> for MyRngSeed {
+ /// fn as_mut(&mut self) -> &mut [u8] {
+ /// &mut self.0
+ /// }
+ /// }
+ ///
+ /// impl SeedableRng for MyRng {
+ /// type Seed = MyRngSeed;
+ ///
+ /// fn from_seed(seed: MyRngSeed) -> MyRng {
+ /// MyRng(seed)
+ /// }
+ /// }
+ /// ```
+ type Seed: Sized + Default + AsMut<[u8]>;
+
+ /// Create a new PRNG using the given seed.
+ ///
+ /// PRNG implementations are allowed to assume that bits in the seed are
+ /// well distributed. That means usually that the number of one and zero
+ /// bits are about equal, and values like 0, 1 and (size - 1) are unlikely.
+ ///
+ /// PRNG implementations are recommended to be reproducible. A PRNG seeded
+ /// using this function with a fixed seed should produce the same sequence
+ /// of output in the future and on different architectures (with for example
+ /// different endianness).
+ ///
+ /// It is however not required that this function yield the same state as a
+ /// reference implementation of the PRNG given equivalent seed; if necessary
+ /// another constructor replicating behaviour from a reference
+ /// implementation can be added.
+ ///
+ /// PRNG implementations should make sure `from_seed` never panics. In the
+ /// case that some special values (like an all zero seed) are not viable
+ /// seeds it is preferable to map these to alternative constant value(s),
+ /// for example `0xBAD5EEDu32` or `0x0DDB1A5E5BAD5EEDu64` ("odd biases? bad
+ /// seed"). This is assuming only a small number of values must be rejected.
+ fn from_seed(seed: Self::Seed) -> Self;
+
+ /// Create a new PRNG using a `u64` seed.
+ ///
+ /// This is a convenience-wrapper around `from_seed` to allow construction
+ /// of any `SeedableRng` from a simple `u64` value. It is designed such that
+ /// low Hamming Weight numbers like 0 and 1 can be used and should still
+ /// result in good, independent seeds to the PRNG which is returned.
+ ///
+ /// This **is not suitable for cryptography**, as should be clear given that
+ /// the input size is only 64 bits.
+ ///
+ /// Implementations for PRNGs *may* provide their own implementations of
+ /// this function, but the default implementation should be good enough for
+ /// all purposes. *Changing* the implementation of this function should be
+ /// considered a value-breaking change.
+ fn seed_from_u64(mut state: u64) -> Self {
+ // We use PCG32 to generate a u32 sequence, and copy to the seed
+ const MUL: u64 = 6364136223846793005;
+ const INC: u64 = 11634580027462260723;
+
+ let mut seed = Self::Seed::default();
+ for chunk in seed.as_mut().chunks_mut(4) {
+ // We advance the state first (to get away from the input value,
+ // in case it has low Hamming Weight).
+ state = state.wrapping_mul(MUL).wrapping_add(INC);
+
+ // Use PCG output function with to_le to generate x:
+ let xorshifted = (((state >> 18) ^ state) >> 27) as u32;
+ let rot = (state >> 59) as u32;
+ let x = xorshifted.rotate_right(rot).to_le();
+
+ unsafe {
+ let p = &x as *const u32 as *const u8;
+ copy_nonoverlapping(p, chunk.as_mut_ptr(), chunk.len());
+ }
+ }
+
+ Self::from_seed(seed)
+ }
+
+ /// Create a new PRNG seeded from another `Rng`.
+ ///
+ /// This is the recommended way to initialize PRNGs with fresh entropy. The
+ /// [`FromEntropy`] trait provides a convenient `from_entropy` method
+ /// based on `from_rng`.
+ ///
+ /// Usage of this method is not recommended when reproducibility is required
+ /// since implementing PRNGs are not required to fix Endianness and are
+ /// allowed to modify implementations in new releases.
+ ///
+ /// It is important to use a good source of randomness to initialize the
+ /// PRNG. Cryptographic PRNG may be rendered insecure when seeded from a
+ /// non-cryptographic PRNG or with insufficient entropy.
+ /// Many non-cryptographic PRNGs will show statistical bias in their first
+ /// results if their seed numbers are small or if there is a simple pattern
+ /// between them.
+ ///
+ /// Prefer to seed from a strong external entropy source like [`OsRng`] or
+ /// from a cryptographic PRNG; if creating a new generator for cryptographic
+ /// uses you *must* seed from a strong source.
+ ///
+ /// Seeding a small PRNG from another small PRNG is possible, but
+ /// something to be careful with. An extreme example of how this can go
+ /// wrong is seeding an Xorshift RNG from another Xorshift RNG, which
+ /// will effectively clone the generator. In general seeding from a
+ /// generator which is hard to predict is probably okay.
+ ///
+ /// PRNG implementations are allowed to assume that a good RNG is provided
+ /// for seeding, and that it is cryptographically secure when appropriate.
+ ///
+ /// [`FromEntropy`]: ../rand/trait.FromEntropy.html
+ /// [`OsRng`]: ../rand/rngs/struct.OsRng.html
+ fn from_rng<R: RngCore>(mut rng: R) -> Result<Self, Error> {
+ let mut seed = Self::Seed::default();
+ rng.try_fill_bytes(seed.as_mut())?;
+ Ok(Self::from_seed(seed))
+ }
+}
+
+// Implement `RngCore` for references to an `RngCore`.
+// Force inlining all functions, so that it is up to the `RngCore`
+// implementation and the optimizer to decide on inlining.
+impl<'a, R: RngCore + ?Sized> RngCore for &'a mut R {
+ #[inline(always)]
+ fn next_u32(&mut self) -> u32 {
+ (**self).next_u32()
+ }
+
+ #[inline(always)]
+ fn next_u64(&mut self) -> u64 {
+ (**self).next_u64()
+ }
+
+ #[inline(always)]
+ fn fill_bytes(&mut self, dest: &mut [u8]) {
+ (**self).fill_bytes(dest)
+ }
+
+ #[inline(always)]
+ fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
+ (**self).try_fill_bytes(dest)
+ }
+}
+
+// Implement `RngCore` for boxed references to an `RngCore`.
+// Force inlining all functions, so that it is up to the `RngCore`
+// implementation and the optimizer to decide on inlining.
+#[cfg(feature="alloc")]
+impl<R: RngCore + ?Sized> RngCore for Box<R> {
+ #[inline(always)]
+ fn next_u32(&mut self) -> u32 {
+ (**self).next_u32()
+ }
+
+ #[inline(always)]
+ fn next_u64(&mut self) -> u64 {
+ (**self).next_u64()
+ }
+
+ #[inline(always)]
+ fn fill_bytes(&mut self, dest: &mut [u8]) {
+ (**self).fill_bytes(dest)
+ }
+
+ #[inline(always)]
+ fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error> {
+ (**self).try_fill_bytes(dest)
+ }
+}
+
+#[cfg(feature="std")]
+impl std::io::Read for RngCore {
+ fn read(&mut self, buf: &mut [u8]) -> Result<usize, std::io::Error> {
+ self.try_fill_bytes(buf)?;
+ Ok(buf.len())
+ }
+}
+
+// Implement `CryptoRng` for references to an `CryptoRng`.
+impl<'a, R: CryptoRng + ?Sized> CryptoRng for &'a mut R {}
+
+// Implement `CryptoRng` for boxed references to an `CryptoRng`.
+#[cfg(feature="alloc")]
+impl<R: CryptoRng + ?Sized> CryptoRng for Box<R> {}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+
+ #[test]
+ fn test_seed_from_u64() {
+ struct SeedableNum(u64);
+ impl SeedableRng for SeedableNum {
+ type Seed = [u8; 8];
+ fn from_seed(seed: Self::Seed) -> Self {
+ let mut x = [0u64; 1];
+ le::read_u64_into(&seed, &mut x);
+ SeedableNum(x[0])
+ }
+ }
+
+ const N: usize = 8;
+ const SEEDS: [u64; N] = [0u64, 1, 2, 3, 4, 8, 16, -1i64 as u64];
+ let mut results = [0u64; N];
+ for (i, seed) in SEEDS.iter().enumerate() {
+ let SeedableNum(x) = SeedableNum::seed_from_u64(*seed);
+ results[i] = x;
+ }
+
+ for (i1, r1) in results.iter().enumerate() {
+ let weight = r1.count_ones();
+ // This is the binomial distribution B(64, 0.5), so chance of
+ // weight < 20 is binocdf(19, 64, 0.5) = 7.8e-4, and same for
+ // weight > 44.
+ assert!(weight >= 20 && weight <= 44);
+
+ for (i2, r2) in results.iter().enumerate() {
+ if i1 == i2 { continue; }
+ let diff_weight = (r1 ^ r2).count_ones();
+ assert!(diff_weight >= 20);
+ }
+ }
+
+ // value-breakage test:
+ assert_eq!(results[0], 5029875928683246316);
+ }
+}