chacha20+salsa20: remove extended-nonce feature gating (#271)

Removes feature gating of `xchacha20` and `xsalsa20`, making them an always-enabled part of the API. This cuts down on a growingly excessive number of feature combinations.
RustCrypto · Aug 29, 2021 · 9e9ee30 · 9e9ee30
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Showing 10 changed files with 32 additions and 69 deletions.
diff --git a/.github/workflows/chacha20.yml b/.github/workflows/chacha20.yml
@@ -42,8 +42,7 @@ jobs:
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features hchacha
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features legacy
       - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features rng
-      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features xchacha
-      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features cipher,force-soft,legacy,rng,xchacha,zeroize
+      - run: cargo build --target ${{ matrix.target }} --release --no-default-features --features cipher,force-soft,legacy,rng,zeroize
 
   # Tests for runtime AVX2 detection
   autodetect:

diff --git a/chacha20/Cargo.toml b/chacha20/Cargo.toml
@@ -18,6 +18,8 @@ edition = "2018"
 
 [dependencies]
 cfg-if = "1"
+
+# optional dependencies
 cipher = { version = "0.3", optional = true }
 rand_core = { version = "0.6", optional = true, default-features = false }
 zeroize = { version = ">=1, <1.5", optional = true, default-features = false }
@@ -30,15 +32,14 @@ cipher = { version = "0.3", features = ["dev"] }
 hex-literal = "0.2"
 
 [features]
-default = ["xchacha"]
+default = ["cipher"]
 expose-core = []
 force-soft = []
-hchacha = ["xchacha"]
+hchacha = ["cipher"]
 legacy = ["cipher"]
 rng = ["rand_core"]
 std = ["cipher/std"]
-xchacha = ["cipher"]
 
 [package.metadata.docs.rs]
-features = ["legacy", "rng", "std", "xchacha"]
+features = ["legacy", "rng", "std"]
 rustdoc-args = ["--cfg", "docsrs"]
diff --git a/chacha20/src/backend.rs b/chacha20/src/backend.rs
@@ -14,12 +14,10 @@ cfg_if! {
         pub(crate) mod autodetect;
         pub(crate) mod avx2;
         pub(crate) mod sse2;
+        pub(crate) mod soft;
 
         pub(crate) use self::autodetect::BUFFER_SIZE;
         pub use self::autodetect::Core;
-
-        #[cfg(feature = "xchacha")]
-        pub(crate) mod soft;
     } else {
         pub(crate) mod soft;
         pub(crate) use self::soft::BUFFER_SIZE;

diff --git a/chacha20/src/lib.rs b/chacha20/src/lib.rs
@@ -13,7 +13,7 @@
 //! - [`ChaCha20`]: standard IETF variant with 96-bit nonce
 //! - [`ChaCha20Legacy`]: (gated under the `legacy` feature) "djb" variant with 64-bit nonce
 //! - [`ChaCha8`] / [`ChaCha12`]: reduced round variants of ChaCha20
-//! - [`XChaCha20`]: (gated under the `xchacha20` feature) 192-bit extended nonce variant
+//! - [`XChaCha20`]: 192-bit extended nonce variant
 //! - [`XChaCha8`] / [`XChaCha12`]: reduced round variants of XChaCha20
 //!
 //! # ⚠️ Security Warning: [Hazmat!]
@@ -42,6 +42,8 @@
 //! # Usage
 //!
 //! ```
+//! # #[cfg(feature = "cipher")]
+//! # {
 //! use chacha20::{ChaCha20, Key, Nonce};
 //! use chacha20::cipher::{NewCipher, StreamCipher, StreamCipherSeek};
 //!
@@ -61,6 +63,7 @@
 //! cipher.seek(0);
 //! cipher.apply_keystream(&mut data);
 //! assert_eq!(data, [1, 2, 3, 4, 5, 6, 7]);
+//! # }
 //! ```
 //!
 //! [RFC 8439]: https://tools.ietf.org/html/rfc8439
@@ -85,14 +88,17 @@ mod max_blocks;
 #[cfg(feature = "rng")]
 mod rng;
 mod rounds;
-#[cfg(feature = "xchacha")]
+#[cfg(feature = "cipher")]
 mod xchacha;
 
 #[cfg(feature = "cipher")]
 pub use cipher;
 
 #[cfg(feature = "cipher")]
-pub use crate::chacha::{ChaCha, ChaCha12, ChaCha20, ChaCha8, Key, Nonce};
+pub use crate::{
+    chacha::{ChaCha, ChaCha12, ChaCha20, ChaCha8, Key, Nonce},
+    xchacha::{XChaCha, XChaCha12, XChaCha20, XChaCha8, XNonce},
+};
 
 #[cfg(feature = "expose-core")]
 pub use crate::{
@@ -111,9 +117,6 @@ pub use rng::{
     ChaCha12Rng, ChaCha12RngCore, ChaCha20Rng, ChaCha20RngCore, ChaCha8Rng, ChaCha8RngCore,
 };
 
-#[cfg(feature = "xchacha")]
-pub use self::xchacha::{XChaCha, XChaCha12, XChaCha20, XChaCha8, XNonce};
-
 /// Size of a ChaCha20 block in bytes
 pub const BLOCK_SIZE: usize = 64;
 

diff --git a/chacha20/src/xchacha.rs b/chacha20/src/xchacha.rs
@@ -16,7 +16,6 @@ use cipher::{
 use core::convert::TryInto;
 
 /// EXtended ChaCha20 nonce (192-bits/24-bytes)
-#[cfg_attr(docsrs, doc(cfg(feature = "xchacha")))]
 pub type XNonce = cipher::Nonce<XChaCha20>;
 
 /// XChaCha20 is a ChaCha20 variant with an extended 192-bit (24-byte) nonce.
@@ -34,24 +33,12 @@ pub type XNonce = cipher::Nonce<XChaCha20>;
 /// and is documented in an (expired) IETF draft:
 ///
 /// <https://tools.ietf.org/html/draft-arciszewski-xchacha-03>
-///
-/// The `xchacha` Cargo feature must be enabled in order to use this
-/// (which it is by default).
-#[cfg_attr(docsrs, doc(cfg(feature = "xchacha")))]
 pub type XChaCha20 = XChaCha<R20>;
 
 /// XChaCha12 stream cipher (reduced-round variant of [`XChaCha20`] with 12 rounds)
-///
-/// The `xchacha` Cargo feature must be enabled in order to use this
-/// (which it is by default).
-#[cfg_attr(docsrs, doc(cfg(feature = "xchacha")))]
 pub type XChaCha12 = XChaCha<R12>;
 
 /// XChaCha8 stream cipher (reduced-round variant of [`XChaCha20`] with 8 rounds)
-///
-/// The `xchacha` Cargo feature must be enabled in order to use this
-/// (which it is by default).
-#[cfg_attr(docsrs, doc(cfg(feature = "xchacha")))]
 pub type XChaCha8 = XChaCha<R8>;
 
 /// XChaCha family stream cipher, generic around a number of rounds.
@@ -60,7 +47,6 @@ pub type XChaCha8 = XChaCha<R8>;
 /// a specific number of rounds.
 ///
 /// Generally [`XChaCha20`] is preferred.
-#[cfg_attr(docsrs, doc(cfg(feature = "xchacha")))]
 pub struct XChaCha<R: Rounds>(ChaCha<R, C64>);
 
 impl<R: Rounds> NewCipher for XChaCha<R> {

diff --git a/chacha20/tests/lib.rs b/chacha20/tests/lib.rs
@@ -1,5 +1,7 @@
 //! Tests for ChaCha20 (IETF and "djb" versions) as well as XChaCha20
 
+#![cfg(feature = "cipher")]
+
 use chacha20::ChaCha20;
 
 // IETF version of ChaCha20 (96-bit nonce)
@@ -10,9 +12,7 @@ mod overflow {
     use cipher::{NewCipher, StreamCipher, StreamCipherSeek};
 
     const OFFSET_256GB: u64 = 256u64 << 30;
-    #[cfg(feature = "xchacha")]
     const OFFSET_256PB: u64 = 256u64 << 50;
-    #[cfg(feature = "xchacha")]
     const OFFSET_1ZB: u128 = (64u128) << 64;
 
     #[test]
@@ -114,7 +114,6 @@ mod overflow {
         }
     }
 
-    #[cfg(feature = "xchacha")]
     #[test]
     fn xchacha_256gb() {
         let mut cipher = chacha20::XChaCha20::new(&Default::default(), &Default::default());
@@ -132,7 +131,6 @@ mod overflow {
             .expect("Couldn't encrypt past the last byte of 256GB");
     }
 
-    #[cfg(feature = "xchacha")]
     #[test]
     fn xchacha_upper_limit() {
         let mut cipher = chacha20::XChaCha20::new(&Default::default(), &Default::default());
@@ -149,7 +147,6 @@ mod overflow {
             .expect_err("Could encrypt past 1 zebibyte");
     }
 
-    #[cfg(feature = "xchacha")]
     #[test]
     fn xchacha_has_a_big_counter() {
         let mut cipher = chacha20::XChaCha20::new(&Default::default(), &Default::default());
@@ -219,17 +216,9 @@ mod chacha20test {
     // <https://datatracker.ietf.org/doc/html/rfc8439#section-2.4.2>
     //
 
-    const KEY: [u8; 32] = hex!(
-        "
-        000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f
-    "
-    );
+    const KEY: [u8; 32] = hex!("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f");
 
-    const IV: [u8; 12] = hex!(
-        "
-        000000000000004a00000000
-    "
-    );
+    const IV: [u8; 12] = hex!("000000000000004a00000000");
 
     const PLAINTEXT: [u8; 114] = hex!(
         "
@@ -241,7 +230,7 @@ mod chacha20test {
         746865206675747572652c2073756e73
         637265656e20776f756c642062652069
         742e
-    "
+        "
     );
 
     const KEYSTREAM: [u8; 114] = hex!(
@@ -251,7 +240,7 @@ mod chacha20test {
         9334794cba40c63e34cdea212c4cf07d41b769a6749f3f
         630f4122cafe28ec4dc47e26d4346d70b98c73f3e9c53a
         c40c5945398b6eda1a832c89c167eacd901d7e2bf363
-    "
+        "
     );
 
     const CIPHERTEXT: [u8; 114] = hex!(
@@ -264,7 +253,7 @@ mod chacha20test {
         52bc514d16ccf806818ce91ab7793736
         5af90bbf74a35be6b40b8eedf2785e42
         874d
-    "
+        "
     );
 
     #[test]
@@ -294,7 +283,6 @@ mod chacha20test {
     }
 }
 
-#[cfg(feature = "xchacha")]
 #[rustfmt::skip]
 mod xchacha20 {
     use chacha20::{Key, XChaCha20, XNonce};

diff --git a/salsa20/Cargo.toml b/salsa20/Cargo.toml
@@ -12,17 +12,17 @@ edition = "2018"
 
 [dependencies]
 cipher = "0.3"
-zeroize = { version = "=1.3", optional = true, default-features = false }
+
+# optional dependencies
+zeroize = { version = ">=1, <1.4", optional = true, default-features = false }
 
 [dev-dependencies]
 cipher = { version = "0.3", features = ["dev"] }
 
 [features]
-default = ["xsalsa20"]
 expose-core = []
-hsalsa20 = ["xsalsa20"]
-xsalsa20 = []
+hsalsa20 = []
 
 [package.metadata.docs.rs]
-features = ["hsalsa20", "xsalsa20"]
+features = ["hsalsa20"]
 rustdoc-args = ["--cfg", "docsrs"]
diff --git a/salsa20/src/lib.rs b/salsa20/src/lib.rs
@@ -62,10 +62,12 @@ pub use cipher;
 mod core;
 mod rounds;
 mod salsa;
-#[cfg(feature = "xsalsa20")]
 mod xsalsa;
 
-pub use crate::salsa::{Key, Nonce, Salsa, Salsa12, Salsa20, Salsa8};
+pub use crate::{
+    salsa::{Key, Nonce, Salsa, Salsa12, Salsa20, Salsa8},
+    xsalsa::{XNonce, XSalsa20},
+};
 
 #[cfg(feature = "expose-core")]
 pub use crate::{
@@ -76,9 +78,6 @@ pub use crate::{
 #[cfg(feature = "hsalsa20")]
 pub use crate::xsalsa::hsalsa20;
 
-#[cfg(feature = "xsalsa20")]
-pub use crate::xsalsa::{XNonce, XSalsa20};
-
 /// Size of a Salsa20 block in bytes
 pub const BLOCK_SIZE: usize = 64;
 

diff --git a/salsa20/src/xsalsa.rs b/salsa20/src/xsalsa.rs
@@ -10,7 +10,6 @@ use cipher::{
 use core::convert::TryInto;
 
 /// EXtended Salsa20 nonce (192-bit/24-byte)
-#[cfg_attr(docsrs, doc(cfg(feature = "xsalsa20")))]
 pub type XNonce = cipher::Nonce<XSalsa20>;
 
 /// XSalsa20 is a Salsa20 variant with an extended 192-bit (24-byte) nonce.
@@ -21,7 +20,6 @@ pub type XNonce = cipher::Nonce<XSalsa20>;
 ///
 /// The `xsalsa20` Cargo feature must be enabled in order to use this
 /// (which it is by default).
-#[cfg_attr(docsrs, doc(cfg(feature = "xsalsa20")))]
 pub struct XSalsa20(Salsa20);
 
 impl NewCipher for XSalsa20 {

diff --git a/salsa20/tests/lib.rs b/salsa20/tests/lib.rs
@@ -2,11 +2,9 @@
 
 use cipher::{generic_array::GenericArray, NewCipher, StreamCipher, StreamCipherSeek};
 use salsa20::Salsa20;
-#[cfg(feature = "xsalsa20")]
 use salsa20::XSalsa20;
 
 cipher::stream_cipher_seek_test!(salsa20_seek, Salsa20);
-#[cfg(feature = "xsalsa20")]
 cipher::stream_cipher_seek_test!(xsalsa20_seek, XSalsa20);
 
 #[cfg(test)]
@@ -15,7 +13,6 @@ const KEY_BYTES: usize = 32;
 #[cfg(test)]
 const IV_BYTES: usize = 8;
 
-#[cfg(feature = "xsalsa20")]
 #[cfg(test)]
 const IV_BYTES_XSALSA20: usize = 24;
 
@@ -37,7 +34,6 @@ const KEY_LONG: [u8; KEY_BYTES] = [
     27, 28, 29, 30, 31, 32,
 ];
 
-#[cfg(feature = "xsalsa20")]
 #[cfg(test)]
 const KEY_XSALSA20: [u8; KEY_BYTES] = *b"this is 32-byte key for xsalsa20";
 
@@ -53,7 +49,6 @@ const IVHI: [u8; IV_BYTES] = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01];
 #[cfg(test)]
 const IV_LONG: [u8; IV_BYTES] = [3, 1, 4, 1, 5, 9, 2, 6];
 
-#[cfg(feature = "xsalsa20")]
 #[cfg(test)]
 const IV_XSALSA20: [u8; IV_BYTES_XSALSA20] = *b"24-byte nonce for xsalsa";
 
@@ -101,7 +96,6 @@ const EXPECTED_LONG: [u8; 256] = [
     0xcb, 0xe6, 0xa7, 0x16, 0x1e, 0x86, 0x53, 0xce, 0x93, 0x91, 0xe1, 0xe6, 0x71, 0x0e, 0xd4, 0xf1,
 ];
 
-#[cfg(feature = "xsalsa20")]
 #[cfg(test)]
 const EXPECTED_XSALSA20_ZEROS: [u8; 64] = [
     0x48, 0x48, 0x29, 0x7f, 0xeb, 0x1f, 0xb5, 0x2f, 0xb6, 0x6d, 0x81, 0x60, 0x9b, 0xd5, 0x47, 0xfa,
@@ -110,7 +104,6 @@ const EXPECTED_XSALSA20_ZEROS: [u8; 64] = [
     0x40, 0x50, 0xd0, 0x8c, 0xe6, 0xd3, 0xa1, 0x51, 0xec, 0x26, 0x5f, 0x3a, 0x58, 0xe4, 0x76, 0x48,
 ];
 
-#[cfg(feature = "xsalsa20")]
 #[cfg(test)]
 const EXPECTED_XSALSA20_HELLO_WORLD: [u8; 12] = [
     0x00, 0x2d, 0x45, 0x13, 0x84, 0x3f, 0xc2, 0x40, 0xc4, 0x01, 0xe5, 0x41,
@@ -186,7 +179,6 @@ fn salsa20_offsets() {
     }
 }
 
-#[cfg(feature = "xsalsa20")]
 #[test]
 fn xsalsa20_encrypt_zeros() {
     let key = GenericArray::from(KEY_XSALSA20);
@@ -201,7 +193,6 @@ fn xsalsa20_encrypt_zeros() {
     }
 }
 
-#[cfg(feature = "xsalsa20")]
 #[test]
 fn xsalsa20_encrypt_hello_world() {
     let key = GenericArray::from(KEY_XSALSA20);