From be8ec280a056be688913c1a35c589ef406f72f50 Mon Sep 17 00:00:00 2001
From: Santo Cariotti <santo@dcariotti.me>
Date: Mon, 23 Jun 2025 09:39:36 +0200
Subject: Add `Keccak512Hasher`

---
 src/hasher.rs | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

(limited to 'src')

diff --git a/src/hasher.rs b/src/hasher.rs
index 088b16a..7692e0f 100644
--- a/src/hasher.rs
+++ b/src/hasher.rs
@@ -1,6 +1,7 @@
 //! Provides hashing abstractions and implementations including SHA256 and a default dummy hasher.
 
 use sha2::{Digest, Sha256};
+use sha3::Keccak512;
 
 /// A trait representing a generic hash function.
 ///
@@ -47,6 +48,30 @@ impl Hasher for SHA256Hasher {
     }
 }
 
+#[derive(Clone)]
+/// A hasher implementation using the Keccak512 cryptographic hash function.
+pub struct Keccak512Hasher;
+
+impl Default for Keccak512Hasher {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Keccak512Hasher {
+    pub fn new() -> Self {
+        Self {}
+    }
+}
+
+impl Hasher for Keccak512Hasher {
+    fn hash(&self, input: &[u8]) -> String {
+        let mut hasher = Keccak512::new();
+        hasher.update(input);
+        hex::encode(hasher.finalize())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -68,4 +93,22 @@ mod tests {
         let actual_hash = hasher.hash(input);
         assert_eq!(actual_hash, expected_hash);
     }
+
+    #[test]
+    fn test_keccak512_hasher_with_known_input() {
+        let hasher = Keccak512Hasher;
+        let input = "hello".as_bytes();
+        let expected_hash = "52fa80662e64c128f8389c9ea6c73d4c02368004bf4463491900d11aaadca39d47de1b01361f207c512cfa79f0f92c3395c67ff7928e3f5ce3e3c852b392f976";
+        let actual_hash = hasher.hash(input);
+        assert_eq!(actual_hash, expected_hash);
+    }
+
+    #[test]
+    fn test_keccak512_hasher_empty_string() {
+        let hasher = Keccak512Hasher;
+        let input = &[];
+        let expected_hash = "0eab42de4c3ceb9235fc91acffe746b29c29a8c366b7c60e4e67c466f36a4304c00fa9caf9d87976ba469bcbe06713b435f091ef2769fb160cdab33d3670680e";
+        let actual_hash = hasher.hash(input);
+        assert_eq!(actual_hash, expected_hash);
+    }
 }
-- 
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