From dab2f0b6b6b501f2680e9fb4cd21c8c80c9f2ae8 Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Mon, 4 Jun 2018 10:23:26 -0400
Subject: [PATCH] Switch fuzztarget SHA256 to simply XOR'ing all input bytes

---
 src/util/sha2.rs | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/src/util/sha2.rs b/src/util/sha2.rs
index 7c819ff..40b4e5b 100644
--- a/src/util/sha2.rs
+++ b/src/util/sha2.rs
@@ -1,64 +1,63 @@
 //! fuzztarget-only Sha2 context with a dummy Sha256 and Sha512 hashers.
 
 use crypto::digest::Digest;
-use crypto::sha2;
 
 #[derive(Clone, Copy)]
 /// Dummy Sha256 that hashes the input, but only returns the first byte of output, masking the
 /// rest to 0s.
 pub struct Sha256 {
-	state: sha2::Sha256,
+	state: u8,
 }
 
 impl Sha256 {
 	/// Constructs a new dummy Sha256 context
 	pub fn new() -> Sha256 {
 		Sha256 {
-			state: sha2::Sha256::new(),
+			state: 0,
 		}
 	}
 }
 
 impl Digest for Sha256 {
 	fn result(&mut self, data: &mut [u8]) {
-		self.state.result(data);
+		data[0] = self.state;
 		for i in 1..32 {
 			data[i] = 0;
 		}
 	}
 
-	fn input(&mut self, data: &[u8]) { self.state.input(data); }
-	fn reset(&mut self) { self.state.reset(); }
-	fn output_bits(&self) -> usize { self.state.output_bits() }
-	fn block_size(&self) -> usize { self.state.block_size() }
+	fn input(&mut self, data: &[u8]) { for i in data { self.state ^= i; } }
+	fn reset(&mut self) { self.state = 0; }
+	fn output_bits(&self) -> usize { 256 }
+	fn block_size(&self) -> usize { 64 }
 }
 
 #[derive(Clone, Copy)]
 /// Dummy Sha512 that hashes the input, but only returns the first byte of output, masking the
 /// rest to 0s.
 pub struct Sha512 {
-	state: sha2::Sha512,
+	state: u8,
 }
 
 impl Sha512 {
 	/// Constructs a new dummy Sha512 context
 	pub fn new() -> Sha512 {
 		Sha512 {
-			state: sha2::Sha512::new(),
+			state: 0xff,
 		}
 	}
 }
 
 impl Digest for Sha512 {
 	fn result(&mut self, data: &mut [u8]) {
-		self.state.result(data);
+		data[0] = self.state;
 		for i in 1..64 {
 			data[i] = 0;
 		}
 	}
 
-	fn input(&mut self, data: &[u8]) { self.state.input(data); }
-	fn reset(&mut self) { self.state.reset(); }
-	fn output_bits(&self) -> usize { self.state.output_bits() }
-	fn block_size(&self) -> usize { self.state.block_size() }
+	fn input(&mut self, data: &[u8]) { for i in data { self.state ^= i; } }
+	fn reset(&mut self) { self.state = 0xff; }
+	fn output_bits(&self) -> usize { 512 }
+	fn block_size(&self) -> usize { 128 }
 }