add hash_public_values

core/Cargo.toml

@@ -59,6 +59,7 @@ web-time = "1.1.0"
 rayon-scan = "0.1.1"
 serial_test = "3.1.1"
 thiserror = "1.0.60"
+num-bigint = "0.4.5"
 
 [dev-dependencies]
 tiny-keccak = { version = "2.0.2", features = ["keccak"] }

core/src/io.rs

@@ -3,6 +3,7 @@ use crate::{
     utils::{BabyBearPoseidon2, Buffer},
 };
 use k256::sha2::{Digest, Sha256};
+use num_bigint::BigUint;
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
 
 /// Standard input for the prover.
@@ -129,18 +130,23 @@ impl SP1PublicValues {
         self.buffer.write_slice(slice);
     }
 
-    /// Hash the public values to get a Bn254 value.
-    pub fn hash_public_values(&self) -> Bn254Fr {
+    /// Hash the public values, mask the top 3 bits and return a BigUint.
+    /// Matches the implementation of hashPublicValues in the Solidity verifier.
+    ///
+    /// ```
+    /// return sha256(publicValues) & bytes32(uint256((1 << 253) - 1));
+    /// ```
+    pub fn hash_public_values(&self) -> BigUint {
         let mut hasher = Sha256::new();
         hasher.update(self.buffer.data.as_slice());
         let hash_result = hasher.finalize();
 
         let mut hash = hash_result.to_vec();
 
         // Mask the top 3 bits.
-        hash[0] &= 0b00111111;
+        hash[0] &= 0b00011111;
 
-        BabyBearPoseidon2::from_bytes(hasher.finalize().as_slice()).unwrap()
+        BigUint::from_bytes_be(&hash)
     }
 }