rand

Fixes

• Fix possible memory safety violation due to deserialization of UniformChar from bad source (#1790)

Changes

• Document required output order of fn partial_shuffle and apply #[must_use] (#1769)
• Avoid usage of unsafe in contexts where non-local memory corruption could invalidate contract (#1791)

Full Changelog: 0.10.1...0.10.2

Fixes

• Fix possible memory safety violation due to deserialization of UniformChar from bad source (#1790)

Changes

• Document required output order of fn partial_shuffle and apply #[must_use] (#1769)
• Avoid usage of unsafe in contexts where non-local memory corruption could invalidate contract (#1791)

This release includes a fix for a soundness bug; see #1763.

Changes

• Document panic behavior of make_rng and add #[track_caller] (#1761)
• Deprecate feature log (#1763)

Full Changelog: 0.10.0...0.10.1

This release includes a fix for a soundness bug; see #1763.

Changes

• Document panic behavior of make_rng and add #[track_caller] (#1761)
• Deprecate feature log (#1763)

[0.10.0] - 2026-02-08

Changes

• The dependency on rand_chacha has been replaced with a dependency on chacha20. This changes the implementation behind StdRng, but the output remains the same. There may be some API breakage when using the ChaCha-types directly as these are now the ones in chacha20 instead of rand_chacha (#1642).
• Rename fns IndexedRandom::choose_multiple -> sample, choose_multiple_array -> sample_array, choose_multiple_weighted -> sample_weighted, struct SliceChooseIter -> IndexedSamples and fns IteratorRandom::choose_multiple -> sample, choose_multiple_fill -> sample_fill (#1632)
• Use Edition 2024 and MSRV 1.85 (#1653)
• Let Fill be implemented for element types, not sliceable types (#1652)
• Fix OsError::raw_os_error on UEFI targets by returning Option<usize> (#1665)
• Replace fn TryRngCore::read_adapter(..) -> RngReadAdapter with simpler struct RngReader (#1669)
• Remove fns SeedableRng::from_os_rng, try_from_os_rng (#1674)
• Remove Clone support for StdRng, ReseedingRng (#1677)
• Use postcard instead of bincode to test the serde feature (#1693)
• Avoid excessive allocation in IteratorRandom::sample when amount is much larger than iterator size (#1695)
• Rename os_rng -> sys_rng, OsRng -> SysRng, OsError -> SysError (#1697)
• Rename Rng -> RngExt as upstream rand_core has renamed RngCore -> Rng (#1717)

Additions

• Add fns IndexedRandom::choose_iter, choose_weighted_iter (#1632)
• Pub export Xoshiro128PlusPlus, Xoshiro256PlusPlus prngs (#1649)
• Pub export ChaCha8Rng, ChaCha12Rng, ChaCha20Rng behind chacha feature (#1659)
• Fn rand::make_rng() -> R where R: SeedableRng (#1734)

Removals

• Removed ReseedingRng (#1722)
• Removed unused feature "nightly" (#1732)
• Removed feature small_rng (#1732)

New Contributors

• @hpenne made their first contribution in #1642
• @usamoi made their first contribution in #1665
• @allan2 made their first contribution in #1680
• @tarcieri made their first contribution in #1683
• @valadaptive made their first contribution in #1693
• @stepancheg made their first contribution in #1695

Full Changelog: 0.9.2...0.10.0

Changes

• The dependency on rand_chacha has been replaced with a dependency on chacha20. This changes the implementation behind StdRng, but the output remains the same. There may be some API breakage when using the ChaCha-types directly as these are now the ones in chacha20 instead of rand_chacha (#1642).
• Rename fns IndexedRandom::choose_multiple -> sample, choose_multiple_array -> sample_array, choose_multiple_weighted -> sample_weighted, struct SliceChooseIter -> IndexedSamples and fns IteratorRandom::choose_multiple -> sample, choose_multiple_fill -> sample_fill (#1632)
• Use Edition 2024 and MSRV 1.85 (#1653)
• Let Fill be implemented for element types, not sliceable types (#1652)
• Fix OsError::raw_os_error on UEFI targets by returning Option<usize> (#1665)
• Replace fn TryRngCore::read_adapter(..) -> RngReadAdapter with simpler struct RngReader (#1669)
• Remove fns SeedableRng::from_os_rng, try_from_os_rng (#1674)
• Remove Clone support for StdRng, ReseedingRng (#1677)
• Use postcard instead of bincode to test the serde feature (#1693)
• Avoid excessive allocation in IteratorRandom::sample when amount is much larger than iterator size (#1695)
• Rename os_rng -> sys_rng, OsRng -> SysRng, OsError -> SysError (#1697)
• Rename Rng -> RngExt as upstream rand_core has renamed RngCore -> Rng (#1717)

Additions

• Add fns IndexedRandom::choose_iter, choose_weighted_iter (#1632)
• Pub export Xoshiro128PlusPlus, Xoshiro256PlusPlus prngs (#1649)
• Pub export ChaCha8Rng, ChaCha12Rng, ChaCha20Rng behind chacha feature (#1659)
• Fn rand::make_rng() -> R where R: SeedableRng (#1734)

Removals

• Removed ReseedingRng (#1722)
• Removed unused feature "nightly" (#1732)
• Removed feature small_rng (#1732)

@newpavlov this includes a number of what I think are uncontroversial
changes from my other PRs and also bumps versions to allow publishing a
new pre-release.

I'm not committing to keeping rand_pcg in this repo but for now this is
the easiest approach (I also wouldn't make changes here until after
v0.10).

Rename Rng => RngExt; bump rand_core to v0.10.0-rc-6 (#1717)

What's Changed

• rand v0.9.5: backport #1790 by @dhardy in #1803

Full Changelog: 0.9.4...0.9.5

Fixes

• Fix doc build (#1766)

Full Changelog: 0.9.3...0.9.4

This release back-ports a fix from v0.10. See also [#1763].

Changes

• Deprecate feature log (#1764)
• Replace usages of doc_auto_cfg (#1764)

Full Changelog: 0.9.2...0.9.3

Deprecated

• Deprecate rand::rngs::mock module and StepRng generator ([#1634])

Additions

• Enable WeightedIndex<usize> (de)serialization ([#1646])

Security and unsafe

• Revise "not a crypto library" policy again (#1565)
• Remove zerocopy dependency from rand (#1579)

Fixes

• Fix feature simd_support for recent nightly rust (#1586)

Changes

• Allow fn rand::seq::index::sample_weighted and fn IndexedRandom::choose_multiple_weighted to return fewer than amount results (#1623), reverting an undocumented change ([#1382]) to the previous release.

Additions

• Add rand::distr::Alphabetic distribution. (#1587)
• Re-export rand_core (#1604)

Security and unsafe

• Policy: "rand is not a crypto library" (#1514)
• Remove fork-protection from ReseedingRng and ThreadRng. Instead, it is recommended to call ThreadRng::reseed on fork. (#1379)
• Use zerocopy to replace some unsafe code (#1349, #1393, #1446, #1502)

Dependencies

• Bump the MSRV to 1.63.0 (#1207, #1246, #1269, #1341, #1416, #1536); note that 1.60.0 may work for dependents when using --ignore-rust-version
• Update to rand_core v0.9.0 (#1558)

Features

• Support std feature without getrandom or rand_chacha (#1354)
• Enable feature small_rng by default (#1455)
• Remove implicit feature rand_chacha; use std_rng instead. (#1473)
• Rename feature serde1 to serde (#1477)
• Rename feature getrandom to os_rng (#1537)
• Add feature thread_rng (#1547)

API changes: rand_core traits

• Add fn RngCore::read_adapter implementing std::io::Read (#1267)
• Add trait CryptoBlockRng: BlockRngCore; make trait CryptoRng: RngCore (#1273)
• Add traits TryRngCore, TryCryptoRng (#1424, #1499)
• Rename fn SeedableRng::from_rng -> try_from_rng and add infallible variant fn from_rng (#1424)
• Rename fn SeedableRng::from_entropy -> from_os_rng and add fallible variant fn try_from_os_rng (#1424)
• Add bounds Clone and AsRef to associated type SeedableRng::Seed (#1491)

API changes: Rng trait and top-level fns

• Rename fn rand::thread_rng() to rand::rng() and remove from the prelude (#1506)
• Remove fn rand::random() from the prelude (#1506)
• Add top-level fns random_iter, random_range, random_bool, random_ratio, fill (#1488)
• Re-introduce fn Rng::gen_iter as random_iter (#1305, #1500)
• Rename fn Rng::gen to random to avoid conflict with the new gen keyword in Rust 2024 (#1438)
• Rename fns Rng::gen_range to random_range, gen_bool to random_bool, gen_ratio to random_ratio (#1505)
• Annotate panicking methods with #[track_caller] (#1442, #1447)

API changes: RNGs

• Fix <SmallRng as SeedableRng>::Seed size to 256 bits (#1455)
• Remove first parameter (rng) of ReseedingRng::new (#1533)

API changes: Sequences

• Split trait SliceRandom into IndexedRandom, IndexedMutRandom, SliceRandom (#1382)
• Add IndexedRandom::choose_multiple_array, index::sample_array (#1453, #1469)

API changes: Distributions: renames

• Rename module rand::distributions to rand::distr (#1470)
• Rename distribution Standard to StandardUniform (#1526)
• Move distr::Slice -> distr::slice::Choose, distr::EmptySlice -> distr::slice::Empty (#1548)
• Rename trait distr::DistString -> distr::SampleString (#1548)
• Rename distr::DistIter -> distr::Iter, distr::DistMap -> distr::Map (#1548)

API changes: Distributions

• Relax Sized bound on Distribution<T> for &D (#1278)
• Remove impl of Distribution<Option<T>> for StandardUniform (#1526)
• Let distribution StandardUniform support all NonZero* types (#1332)
• Fns {Uniform, UniformSampler}::{new, new_inclusive} return a Result (instead of potentially panicking) (#1229)
• Distribution Uniform implements TryFrom instead of From for ranges (#1229)
• Add UniformUsize (#1487)
• Remove support for generating isize and usize values with StandardUniform, Uniform (except via UniformUsize) and Fill and usage as a WeightedAliasIndex weight (#1487)
• Add impl DistString for distributions Slice<char> and Uniform<char> (#1315)
• Add fn Slice::num_choices (#1402)
• Add fn p() for distribution Bernoulli to access probability (#1481)

API changes: Weighted distributions

• Add pub module rand::distr::weighted, moving WeightedIndex there (#1548)
• Add trait weighted::Weight, allowing WeightedIndex to trap overflow (#1353)
• Add fns weight, weights, total_weight to distribution WeightedIndex (#1420)
• Rename enum WeightedError to weighted::Error, revising variants (#1382) and mark as #[non_exhaustive] (#1480)

API changes: SIMD

• Switch to std::simd, expand SIMD & docs (#1239)

Reproducibility-breaking changes

• Make ReseedingRng::reseed discard remaining data from the last block generated (#1379)
• Change fn SmallRng::seed_from_u64 implementation (#1203)
• Allow UniformFloat::new samples and UniformFloat::sample_single to yield high (#1462)
• Fix portability of distribution Slice (#1469)
• Make Uniform for usize portable via UniformUsize (#1487)
• Fix IndexdRandom::choose_multiple_weighted for very small seeds and optimize for large input length / low memory (#1530)

Reproducibility-breaking optimisations

• Optimize fn sample_floyd, affecting output of rand::seq::index::sample and rand::seq::SliceRandom::choose_multiple (#1277)
• New, faster algorithms for IteratorRandom::choose and choose_stable (#1268)
• New, faster algorithms for SliceRandom::shuffle and partial_shuffle (#1272)
• Optimize distribution Uniform: use Canon's method (single sampling) / Lemire's method (distribution sampling) for faster sampling (breaks value stability; #1287)
• Optimize fn sample_single_inclusive for floats (+~20% perf) (#1289)

Other optimisations

• Improve SmallRng initialization performance (#1482)
• Optimise SIMD widening multiply (#1247)

Other

• Add Cargo.lock.msrv file (#1275)
• Reformat with rustfmt and enforce (#1448)
• Apply Clippy suggestions and enforce (#1448, #1474)
• Move all benchmarks to new benches crate (#1329, #1439) and migrate to Criterion (#1490)

Documentation

• Improve ThreadRng related docs (#1257)
• Docs: enable experimental --generate-link-to-definition feature (#1327)
• Better doc of crate features, use doc_auto_cfg (#1411, #1450)

What's Changed

• rand v0.8.7: backport #1790 by @dhardy in #1804

Full Changelog: 0.8.6...0.8.7

What's Changed

This release back-ports a fix from v0.10. See also #1763.

Changes

• Deprecate feature log (#1772)

• Drop the experimental simd_support feature.

New Contributors

• @nwalfield made their first contribution in #1772

Full Changelog: 0.8.5...0.8.6

Fixes

• Fix build on non-32/64-bit architectures (#1144)
• Fix "min_const_gen" feature for no_std (#1173)
• Check libc::pthread_atfork return value with panic on error (#1178)
• More robust reseeding in case ReseedingRng is used from a fork handler (#1178)
• Fix nightly: remove unused slice_partition_at_index feature (#1215)
• Fix nightly + simd_support: update packed_simd (#1216)

Rngs

• StdRng: Switch from HC128 to ChaCha12 on emscripten (#1142). We now use ChaCha12 on all platforms.

Documentation

• Added docs about rand's use of const generics (#1150)
• Better random chars example (#1157)

Additions

• Use const-generics to support arrays of all sizes ([#1104])
• Implement Clone and Copy for Alphanumeric ([#1126])
• Add Distribution::map to derive a distribution using a closure ([#1129])
• Add Slice distribution ([#1107])
• Add DistString trait with impls for Standard and Alphanumeric ([#1133])

Other

• Reorder asserts in Uniform float distributions for easier debugging of non-finite arguments ([#1094], [#1108])
• Add range overflow check in Uniform float distributions ([#1108])
• Deprecate rngs::adapter::ReadRng ([#1130])

Fixes

• Fix no-std + alloc build by gating choose_multiple_weighted on std ([#1088])

Fixes

• Fix panic in UniformInt::sample_single_inclusive and Rng::gen_range when providing a full integer range (eg 0..=MAX) ([#1087])

Other

• Enable all stable features in the playground ([#1081])

Platform support

• The minimum supported Rust version is now 1.36 (#1011)
• getrandom updated to v0.2 (#1041)
• Remove wasm-bindgen and stdweb feature flags. For details of WASM support, see the getrandom documentation. (#948)
• ReadRng::next_u32 and next_u64 now use little-Endian conversion instead of native-Endian, affecting results on Big-Endian platforms (#1061)
• The nightly feature no longer implies the simd_support feature (#1048)
• Fix simd_support feature to work on current nightlies (#1056)

Rngs

• ThreadRng is no longer Copy to enable safe usage within thread-local destructors (#1035)
• gen_range(a, b) was replaced with gen_range(a..b). gen_range(a..=b) is also supported. Note that a and b can no longer be references or SIMD types. (#744, #1003)
• Replace AsByteSliceMut with Fill and add support for [bool], [char], [f32], [f64] (#940)
• Restrict rand::rngs::adapter to std (#1027; see also [#928])
• StdRng: add new std_rng feature flag (enabled by default, but might need to be used if disabling default crate features) (#948)
• StdRng: Switch from ChaCha20 to ChaCha12 for better performance (#1028)
• SmallRng: Replace PCG algorithm with xoshiro{128,256}++ (#1038)

Sequences

• Add IteratorRandom::choose_stable as an alternative to choose which does not depend on size hints (#1057)
• Improve accuracy and performance of IteratorRandom::choose (#1059)
• Implement IntoIterator for IndexVec, replacing the into_iter method (#1007)
• Add value stability tests for seq module (#933)

Misc

• Support PartialEq and Eq for StdRng, SmallRng and StepRng (#979)
• Added a serde1 feature and added Serialize/Deserialize to UniformInt and WeightedIndex (#974)
• Drop some unsafe code (#962, #963, #1011)
• Reduce packaged crate size (#983)
• Migrate to GitHub Actions from Travis+AppVeyor (#1073)

Distributions

• Alphanumeric samples bytes instead of chars (#935)
• Uniform now supports char, enabling rng.gen_range('A'..='Z') (#1068)
• Add UniformSampler::sample_single_inclusive (#1003)

Weighted sampling

• Implement weighted sampling without replacement (#976, #1013)
• rand::distributions::alias_method::WeightedIndex was moved to rand_distr::WeightedAliasIndex. The simpler alternative rand::distribution::WeightedIndex remains. (#945)
• Improve treatment of rounding errors in WeightedIndex::update_weights (#956)
• WeightedIndex: return error on NaN instead of panic (#1005)

Documentation

• Document types supported by random (#994)
• Document notes on password generation (#995)
• Note that SmallRng may not be the best choice for performance and in some other cases (#1038)
• Use doc(cfg) to annotate feature-gated items (#1019)
• Adjust README (#1065)

Fixes

• The Bernoulli distribution constructors now reports an error on NaN and on denominator == 0. ([#925])
• Use std::sync::Once to register fork handler, avoiding possible atomicity violation ([#928])
• Fix documentation on the precision of generated floating-point values

Changes

• Unix: make libc dependency optional; only use fork protection with std feature ([#928])

Additions

• Implement std::error::Error for BernoulliError ([#919])

Fixes

• Fix dependency on rand_core 0.5.1 ([#890])

Additions

• Unit tests for value stability of distributions added ([#888])

Yanked

This release was yanked since it depends on rand_core::OsRng added in 0.5.1 but specifies a dependency on version 0.5.0 ([#890]), causing broken builds when updating from rand 0.7.0 without also updating rand_core.

Fixes

• Fix no_std behaviour, appropriately enable c2-chacha's std feature ([#844])
• alloc feature in no_std is available since Rust 1.36 ([#856])
• Fix or squelch issues from Clippy lints ([#840])

Additions

• Add a no_std target to CI to continuously evaluate no_std status ([#844])
• WeightedIndex: allow adjusting a sub-set of weights ([#866])

Fixes

• Fix incorrect pointer usages revealed by Miri testing (#780, #781)
• Fix (tiny!) bias in Uniform for 8- and 16-bit ints (#809)

Crate

• Bumped MSRV (min supported Rust version) to 1.32.0
• Updated to Rust Edition 2018 (#823, #824)
• Removed dependence on rand_xorshift, rand_isaac, rand_jitter crates (#759, #765)
• Remove dependency on winapi (#724)
• Removed all build.rs files (#824)
• Removed code already deprecated in version 0.6 (#757)
• Removed the serde1 feature (It's still available for backwards compatibility, but it does not do anything. #830)
• Many documentation changes

rand_core

• Updated to rand_core 0.5.0
• Error type redesigned with new API (#800)
• Move from_entropy method to SeedableRng and remove FromEntropy (#800)
• SeedableRng::from_rng is now expected to be value-stable (#815)

Standard RNGs

• OS interface moved from rand_os to new getrandom crate (#765, getrandom)
• Use ChaCha for StdRng and ThreadRng (#792)
• Feature-gate SmallRng (#792)
• ThreadRng now supports Copy (#758)
• Deprecated EntropyRng (#765)
• Enable fork protection of ReseedingRng without std (#724)

Distributions

• Many distributions have been moved to rand_distr (#761)
• Bernoulli::new constructor now returns a Result (#803)
• Distribution::sample_iter adjusted for more flexibility (#758)
• Added distributions::weighted::alias_method::WeightedIndex for O(1) sampling (#692)
• Support sampling NonZeroU* types with the Standard distribution (#728)
• Optimised Binomial distribution sampling (#735, #740, #752)
• Optimised SIMD float sampling (#739)

Sequences

• Make results portable across 32- and 64-bit by using u32 samples for usize where possible (#809)

Crates

• Update rand_core to 0.4 ([#703])
• Move JitterRng to its own crate ([#685])
• Add a wasm-bindgen test crate ([#696])

Platforms

• Fuchsia: Replaced fuchsia-zircon with fuchsia-cprng

Doc

• Use RFC 1946 for doc links ([#691])
• Fix some doc links and notes ([#711])

Fixes

• Move wasm-bindgen shims to correct crate ([#686])
• Make wasm32-unknown-unknown compile but fail at run-time if missing bindings ([#686])

Fixes

• Make the std feature require the optional rand_os dependency ([#675])
• Re-export the optional WASM dependencies of rand_os from rand to avoid breakage ([#674])

Additions

• Add Default for ThreadRng ([#657])
• Move rngs::OsRng to rand_os sub-crate; clean up code; use as dependency ([#643])
• Add rand_xoshiro sub-crate, plus benchmarks ([#642], [#668])

Fixes

• Fix bias in UniformInt::sample_single ([#662])
• Use autocfg instead of rustc_version for rustc version detection ([#664])
• Disable i128 and u128 if the target_os is emscripten ([#671]: work-around Emscripten limitation)
• CI fixes ([#660], [#671])

Optimisations

• Optimise memory usage of UnitCircle and UnitSphereSurface distributions (no PR)

• Support sampling Duration also for no_std (only since Rust 1.25) ([#649])
• Disable default features of libc ([#647])

Project organisation

• Rand has moved from rust-lang-nursery to rust-random! (#578)
• Created The Rust Random Book (source)
• Update copyright and licence notices (#591, #611)
• Migrate policy documentation from the wiki (#544)

Platforms

• Add fork protection on Unix (#466)
• Added support for wasm-bindgen (#541, #559, #562, #600)
• Enable OsRng for powerpc64, sparc and sparc64 (#609)
• Use syscall from libc on Linux instead of redefining it (#629)

RNGs

• Switch SmallRng to use PCG (#623)
• Implement Pcg32 and Pcg64Mcg generators (#632)
• Move ISAAC RNGs to a dedicated crate (#551)
• Move Xorshift RNG to its own crate (#557)
• Move ChaCha and HC128 RNGs to dedicated crates (#607, #636)
• Remove usage of Rc from ThreadRng (#615)

Sampling and distributions

• Implement Rng.gen_ratio() and Bernoulli::new_ratio() (#491)
• Make Uniform strictly respect f32 / f64 high/low bounds (#477)
• Allow gen_range and Uniform to work on non-Copy types (#506)
• Uniform supports inclusive ranges: Uniform::from(a..=b). This is automatically enabled for Rust >= 1.27. (#566)
• Implement TrustedLen and FusedIterator for DistIter (#620)

New distributions

• Add the Dirichlet distribution (#485)
• Added sampling from the unit sphere and circle (#567)
• Implement the triangular distribution (#575)
• Implement the Weibull distribution (#576)
• Implement the Beta distribution (#574)

Optimisations

• Optimise Bernoulli::new (#500)
• Optimise char sampling (#519)
• Optimise sampling of std::time::Duration (#583)

Sequences

• Redesign the seq module (#483, #515)
• Add WeightedIndex and choose_weighted (#518, #547)
• Optimised and changed return type of the sample_indices function (#479)
• Use Iterator::size_hint() to speed up IteratorRandom::choose (#593)

SIMD

• Support for generating SIMD types (#523, #542, #561, #630)

Other

• Revise CI scripts (#632, #635)
• Remove functionality already deprecated in 0.5 (#499)
• Support for i128 and u128 is automatically enabled for Rust >= 1.26. This renders the i128_support feature obsolete. It still exists for backwards compatibility but does not have any effect. This breaks programs using Rand with i128_support on nightlies older than Rust 1.26. (#571)

Documentation

• Fix links in documentation ([#582])

Platform support

• Make OsRng work via WASM/stdweb for WebWorkers

Platform support

• OpenBSD, Bitrig: fix compilation (broken in 0.5.1) ([#530])

Platform support

• Hide OsRng and JitterRng on unsupported platforms ([#512]; fixes [#503])

New distributions

• Added Cauchy distribution. ([#474], [#486])
• Added Pareto distribution. ([#495])

Platform support and OsRng

• Remove blanket Unix implementation. ([#484])
• Remove Wasm unimplemented stub. ([#484])
• Dragonfly BSD: read from /dev/random. ([#484])
• Bitrig: use getentropy like OpenBSD. ([#484])
• Solaris: (untested) use getrandom if available, otherwise /dev/random. ([#484])
• Emscripten, stdweb: split the read up in chunks. ([#484])
• Emscripten, Haiku: don't do an extra blocking read from /dev/random. ([#484])
• Linux, NetBSD, Solaris: read in blocking mode on first use in fill_bytes. ([#484])
• Fuchsia, CloudABI: fix compilation (broken in Rand 0.5). ([#484])

Crate features and organisation

• Minimum Rust version update: 1.22.0. (#239)
• Create a separate rand_core crate. (#288)
• Deprecate rand_derive. (#256)
• Add prelude (and module reorganisation). (#435)
• Add log feature. Logging is now available in JitterRng, OsRng, EntropyRng and ReseedingRng. (#246)
• Add serde1 feature for some PRNGs. (#189)
• stdweb feature for OsRng support on WASM via stdweb. (#272, #336)

Rng trait

• Split Rng into RngCore and Rng extension trait. next_u32, next_u64 and fill_bytes are now part of RngCore. (#265)
• Add Rng::sample. (#256)
• Deprecate Rng::gen_weighted_bool. (#308)
• Add Rng::gen_bool. (#308)
• Remove Rng::next_f32 and Rng::next_f64. (#273)
• Add optimized Rng::fill and Rng::try_fill methods. (#247)
• Deprecate Rng::gen_iter. (#286)
• Deprecate Rng::gen_ascii_chars. (#279)

rand_core crate

• rand now depends on new rand_core crate (#288)
• RngCore and SeedableRng are now part of rand_core. (#288)
• Add modules to help implementing RNGs impl and le. (#209, #228)
• Add Error and ErrorKind. (#225)
• Add CryptoRng marker trait. (#273)
• Add BlockRngCore trait. (#281)
• Add BlockRng and BlockRng64 wrappers to help implementations. (#281, #325)
• Revise the SeedableRng trait. (#233)
• Remove default implementations for RngCore::next_u64 and RngCore::fill_bytes. (#288)
• Add RngCore::try_fill_bytes. (#225)

Other traits and types

• Add FromEntropy trait. (#233, #375)
• Add SmallRng wrapper. (#296)
• Rewrite ReseedingRng to only work with BlockRngCore (substantial performance improvement). (#281)
• Deprecate weak_rng. Use SmallRng instead. (#296)
• Deprecate AsciiGenerator. (#279)

Random number generators

• Switch StdRng and thread_rng to HC-128. (#277)
• StdRng must now be created with from_entropy instead of new
• Change thread_rng reseeding threshold to 32 MiB. (#277)
• PRNGs no longer implement Copy. (#209)
• Debug implementations no longer show internals. (#209)
• Implement Clone for ReseedingRng, JitterRng, OsRng`. (#383, #384)
• Implement serialization for XorShiftRng, IsaacRng and Isaac64Rng under the serde1 feature. (#189)
• Implement BlockRngCore for ChaChaCore and Hc128Core. (#281)
• All PRNGs are now portable across big- and little-endian architectures. (#209)
• Isaac64Rng::next_u32 no longer throws away half the results. (#209)
• Add IsaacRng::new_from_u64 and Isaac64Rng::new_from_u64. (#209)
• Add the HC-128 CSPRNG Hc128Rng. (#210)
• Change ChaCha20 to have 64-bit counter and 64-bit stream. (#349)
• Changes to JitterRng to get its size down from 2112 to 24 bytes. (#251)
• Various performance improvements to all PRNGs.

Platform support and OsRng

• Add support for CloudABI. (#224)
• Remove support for NaCl. (#225)
• WASM support for OsRng via stdweb, behind the stdweb feature. (#272, #336)
• Use getrandom on more platforms for Linux, and on Android. (#338)
• Use the SecRandomCopyBytes interface on macOS. (#322)
• On systems that do not have a syscall interface, only keep a single file descriptor open for OsRng. (#239)
• On Unix, first try a single read from /dev/random, then /dev/urandom. (#338)
• Better error handling and reporting in OsRng (using new error type). (#225)
• OsRng now uses non-blocking when available. (#225)
• Add EntropyRng, which provides OsRng, but has JitterRng as a fallback. (#235)

Distributions

• New Distribution trait. (#256)
• Add Distribution::sample_iter and Rng::::sample_iter. (#361)
• Deprecate Rand, Sample and IndependentSample traits. (#256)
• Add a Standard distribution (replaces most Rand implementations). (#256)
• Add Binomial and Poisson distributions. (#96)
• Add Bernoulli dsitribution. (#411)
• Add Alphanumeric distribution. (#279)
• Remove Closed01 distribution, add OpenClosed01. (#274, #420)
• Rework Range type, making it possible to implement it for user types. (#274)
• Rename Range to Uniform. (#395)
• Add Uniform::new_inclusive for inclusive ranges. (#274)
• Use widening multiply method for much faster integer range reduction. (#274)
• Standard distribution for char uses Uniform internally. (#274)
• Standard distribution for bool uses sign test. (#274)
• Implement Standard distribution for Wrapping<T>. (#436)
• Implement Uniform distribution for Duration. (#427)

Platforms

• Fuchsia: Replaced fuchsia-zircon with fuchsia-cprng

Fixed

• Remove dependency on default features of rand_core ([#689])

Version yanked due to semver-breaking change ([#688]).

Added

• SGX support

Fixed

• Use correct syscall number for PowerPC ([#589])

Changed

• Use winapi on Windows
• Update for Fuchsia OS
• Remove dev-dependency on log