chacha20poly1305: bump chacha20 crate; MSRV 1.49+ (#254)

Like we did with the `aes` crate in #252, this bumps the `chacha20`
crate to a version which implements runtime CPU feature detection
(AVX2/SSE2) and uses new support for `ManuallyDrop` union fields which
became available in Rust 1.49.

Author: tarcieri

.github/workflows/aes-gcm-siv.yml

@@ -25,7 +25,7 @@ jobs:
           - 1.49.0 # MSRV
           - stable
         target:
-          # - armv7-none-eabi TODO: test after MSRV is bumped to 1.42
+          - armv7a-none-eabi
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:

.github/workflows/aes-gcm.yml

@@ -25,7 +25,7 @@ jobs:
           - 1.49.0 # MSRV
           - stable
         target:
-          # - armv7-none-eabi TODO: test after MSRV is bumped to 1.42
+          - armv7a-none-eabi
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:

.github/workflows/aes-siv.yml

@@ -25,7 +25,7 @@ jobs:
           - 1.49.0 # MSRV
           - stable
         target:
-          # - armv7-none-eabi TODO: test after MSRV is bumped to 1.42
+          - armv7a-none-eabi
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:

.github/workflows/chacha20poly1305.yml

@@ -22,10 +22,10 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.41.0 # MSRV
+          - 1.49.0 # MSRV
           - stable
         target:
-          # - armv7-none-eabi TODO: test after MSRV is bumped to 1.42
+          - armv7a-none-eabi
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:
@@ -43,7 +43,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.41.0 # MSRV
+          - 1.49.0 # MSRV
           - stable
     steps:
       - uses: actions/checkout@v1

.github/workflows/crypto_box.yml

@@ -23,10 +23,9 @@ jobs:
 #    strategy:
 #      matrix:
 #        rust:
-#          - 1.41.0 # MSRV
+#          - 1.49.0 # MSRV
 #          - stable
 #        target:
-#          # - armv7-none-eabi TODO: test after MSRV is bumped to 1.42
 #          - thumbv7em-none-eabi
 #          - wasm32-unknown-unknown
 #    steps:
@@ -44,7 +43,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.41.0 # MSRV
+          - 1.49.0 # MSRV
           - stable
     steps:
       - uses: actions/checkout@v1
@@ -62,7 +61,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: 1.41.0 # MSRV
+          toolchain: 1.49.0 # MSRV
           components: clippy
           override: true
       - run: cargo clippy -- -D warnings

.github/workflows/eax.yml

@@ -25,7 +25,6 @@ jobs:
           - 1.41.0 # MSRV
           - stable
         target:
-          # - armv7-none-eabi TODO: test after MSRV is bumped to 1.42
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:

.github/workflows/mgm.yml

@@ -25,7 +25,6 @@ jobs:
           - 1.41.0 # MSRV
           - stable
         target:
-          # - armv7-none-eabi TODO: test after MSRV is bumped to 1.42
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:

.github/workflows/xsalsa20poly1305.yml

@@ -25,7 +25,6 @@ jobs:
           - 1.41.0 # MSRV
           - stable
         target:
-          # - armv7-none-eabi TODO: test after MSRV is bumped to 1.42
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:

Cargo.lock

@@ -31,20 +31,6 @@ in the Transport Layer Security (TLS) protocol. The underlying ChaCha20 cipher
 is also widely used as a cryptographically secure random number generator,
 including internal use by the Rust standard library.
 
-## Performance Notes
-
-By default this crate will use portable software implementations of the
-underlying ChaCha20 and Poly1305 ciphers it's based on.
-
-When targeting modern x86/x86_64 CPUs, use the following `RUSTFLAGS` to
-take advantage of AVX2 acceleration:
-
-    RUSTFLAGS="-Ctarget-feature=+avx2"
-
-Ideally target the `haswell` or `skylake` architectures as a baseline:
-
-    RUSTFLAGS="-Ctarget-cpu=haswell -Ctarget-feature=+avx2"
-
 ## Security Notes
 
 This crate has received one [security audit by NCC Group][5], with no significant
@@ -81,7 +67,7 @@ dual licensed as above, without any additional terms or conditions.
 [docs-image]: https://docs.rs/chacha20poly1305/badge.svg
 [docs-link]: https://docs.rs/chacha20poly1305/
 [license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
-[rustc-image]: https://img.shields.io/badge/rustc-1.41+-blue.svg
+[rustc-image]: https://img.shields.io/badge/rustc-1.49+-blue.svg
 [codecov-image]: https://codecov.io/gh/RustCrypto/AEADs/branch/master/graph/badge.svg
 [codecov-link]: https://codecov.io/gh/RustCrypto/AEADs
 [chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg