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Merged
newpavlov merged 2 commits into from
Sep 10, 2025
Merged

pbkdf2: remove the parallel crate feature #702

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pbkdf2: remove the `parallel` crate feature
newpavlov Sep 10, 2025
0299ab5
Update changelog
newpavlov Sep 10, 2025
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14 changes: 11 additions & 3 deletions Cargo.lock
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6 changes: 6 additions & 0 deletions pbkdf2/CHANGELOG.md
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Expand Up @@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## 0.13.0 (UNRELEASED)
### Removed
- The `parallel` crate feature ([#702])

[#702]: https://github.com/RustCrypto/password-hashes/pull/702

## 0.12.2 (2023-07-08)
### Fixed
- Use `RECOMMENDED_ROUNDS` in `Default` impl for `Params` ([#442])
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3 changes: 0 additions & 3 deletions pbkdf2/Cargo.toml
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Expand Up @@ -17,7 +17,6 @@ rust-version = "1.85"
digest = { version = "0.11.0-rc.1", features = ["mac"] }

# optional dependencies
rayon = { version = "1.7", optional = true }
password-hash = { version = "0.6.0-rc.0", default-features = false, optional = true, features = ["rand_core"] }
hmac = { version = "0.13.0-rc.1", default-features = false, optional = true }
sha1 = { version = "0.11.0-rc.2", default-features = false, optional = true }
Expand All @@ -34,8 +33,6 @@ belt-hash = "0.2.0-rc.1"
[features]
default = ["hmac"]
std = ["password-hash/os_rng"]

parallel = ["rayon", "std"]
simple = ["hmac", "password-hash", "sha2"]

[package.metadata.docs.rs]
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35 changes: 14 additions & 21 deletions pbkdf2/src/lib.rs
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Expand Up @@ -3,11 +3,18 @@
//!
//! # Examples
//!
//! PBKDF2 is defined in terms of a keyed pseudo-random function (PRF). Most
//! commonly HMAC is used as this PRF. In such cases you can use [`pbkdf2_hmac`]
//! and [`pbkdf2_hmac_array`] functions. The former accepts a byte slice which
//! gets filled with generated key, while the latter returns an array with
//! generated key of requested length.
//! PBKDF2 is defined in terms of a keyed pseudo-random function (PRF).
//! The most commonly used PRF for this purpose is HMAC. In such cases
//! you can use [`pbkdf2_hmac`] and [`pbkdf2_hmac_array`] functions.
//! The former accepts a byte slice which gets filled with generated key,
//! while the latter returns an array with generated key of requested length.
//!
//! Note that it is not recommended to generate keys using PBKDF2 that exceed
//! the output size of the PRF (equal to the hash size in the case of HMAC).
//! If you need to generate a large amount of cryptographic material,
//! consider using a separate [key derivation function][KDF].
//!
//! [KDF]: https://github.com/RustCrypto/KDFs
//!
//! ```
//! # #[cfg(feature = "hmac")] {
Expand Down Expand Up @@ -96,9 +103,6 @@ pub use hmac;
#[cfg(feature = "simple")]
pub use crate::simple::{Algorithm, Params, Pbkdf2};

#[cfg(feature = "parallel")]
use rayon::prelude::*;

use digest::{FixedOutput, InvalidLength, KeyInit, Update, typenum::Unsigned};

#[cfg(feature = "hmac")]
Expand Down Expand Up @@ -162,21 +166,10 @@ where
PRF: KeyInit + Update + FixedOutput + Clone + Sync,
{
let n = PRF::OutputSize::to_usize();
// note: HMAC can be initialized with keys of any size,
// so this panic never happens with it
let prf = PRF::new_from_slice(password)?;

#[cfg(not(feature = "parallel"))]
{
for (i, chunk) in res.chunks_mut(n).enumerate() {
pbkdf2_body(i as u32, chunk, &prf, salt, rounds);
}
}
#[cfg(feature = "parallel")]
{
res.par_chunks_mut(n).enumerate().for_each(|(i, chunk)| {
pbkdf2_body(i as u32, chunk, &prf, salt, rounds);
});
for (i, chunk) in res.chunks_mut(n).enumerate() {
pbkdf2_body(i as u32, chunk, &prf, salt, rounds);
}

Ok(())
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