Remove the Keccak C library and use the pure Rust impl (#8657)

* Add license and readme

* Use pure rust implementation

* Bump version to 0.1.1

* Don't use C, prefer the pure Rust implementation

* Add test for `write_keccak`

* Bump version

* Add benchmarks

* Add benchmarks

* Add keccak_256, keccak_512, keccak_256_unchecked and keccak_512_unchecked – mostly for compatibility with ethash

* Remove failed git merge attempt from external git repo
Cargo.lock updates

* whitespace

* Mark unsafe function unsafe

* Unsafe calls in unsafe block

* Document unsafety invariants

* Revert unintended changes to Cargo.lock

ethash/src/keccak.rs

@@ -21,32 +21,36 @@ pub type H256 = [u8; 32];
 pub mod keccak_512 {
 	use super::hash;
 
-	pub use self::hash::keccak_512 as unchecked;
+	pub use self::hash::keccak_512_unchecked as unchecked;
 
 	pub fn write(input: &[u8], output: &mut [u8]) {
-		unsafe { hash::keccak_512(output.as_mut_ptr(), output.len(), input.as_ptr(), input.len()) };
+		hash::keccak_512(input, output);
 	}
 
 	pub fn inplace(input: &mut [u8]) {
-		// This is safe since `sha3_*` uses an internal buffer and copies the result to the output. This
+		// This is safe since `keccak_*` uses an internal buffer and copies the result to the output. This
 		// means that we can reuse the input buffer for both input and output.
-		unsafe { hash::keccak_512(input.as_mut_ptr(), input.len(), input.as_ptr(), input.len()) };
+		unsafe {
+			hash::keccak_512_unchecked(input.as_mut_ptr(), input.len(), input.as_ptr(), input.len());
+		}
 	}
 }
 
 pub mod keccak_256 {
 	use super::hash;
 
-	pub use self::hash::keccak_256 as unchecked;
+	pub use self::hash::keccak_256_unchecked as unchecked;
 
 	#[allow(dead_code)]
 	pub fn write(input: &[u8], output: &mut [u8]) {
-		unsafe { hash::keccak_256(output.as_mut_ptr(), output.len(), input.as_ptr(), input.len()) };
+		hash::keccak_256(input, output);
 	}
 
 	pub fn inplace(input: &mut [u8]) {
-		// This is safe since `sha3_*` uses an internal buffer and copies the result to the output. This
+		// This is safe since `keccak_*` uses an internal buffer and copies the result to the output. This
 		// means that we can reuse the input buffer for both input and output.
-		unsafe { hash::keccak_256(input.as_mut_ptr(), input.len(), input.as_ptr(), input.len()) };
+		unsafe {
+			hash::keccak_256_unchecked(input.as_mut_ptr(), input.len(), input.as_ptr(), input.len());
+		}
 	}
 }