feat: implement Plonk Bn254 proof verification for Solidity format

- Introduced a new `VerifySolidity` function in `verify.go` for proof verification with Solidity, complete with unmarshalling of solidity proof, public witness creation, and proof verification
- Created a new function `verify_plonk_bn254_solidity` in `native.rs` to handle plonk bn254 verification for solidity
- Incorporated a new function `VerifyPlonkBn254Solidity` in `main.go` for Plonk Bn254 proofs verification for Solidity

recursion/gnark-ffi/go/main.go

@@ -72,6 +72,21 @@ func VerifyPlonkBn254(dataDir *C.char, proof *C.char, vkeyHash *C.char, commited
 	return nil
 }
 
+//export VerifyPlonkBn254Solidity
+func VerifyPlonkBn254Solidity(dataDir *C.char, proof *C.char, vkeyHash *C.char, commitedValuesDigest *C.char) *C.char {
+	dataDirString := C.GoString(dataDir)
+	proofString := C.GoString(proof)
+	vkeyHashString := C.GoString(vkeyHash)
+	commitedValuesDigestString := C.GoString(commitedValuesDigest)
+
+	err := sp1.VerifySolidity(dataDirString, proofString, vkeyHashString, commitedValuesDigestString)
+	if err != nil {
+		return C.CString(err.Error())
+	}
+	return nil
+}
+
+
 var testMutex = &sync.Mutex{}
 
 //export TestPlonkBn254

recursion/gnark-ffi/go/sp1/verify.go

@@ -6,7 +6,9 @@ import (
 	"os"
 
 	"github.com/consensys/gnark-crypto/ecc"
+	"github.com/consensys/gnark-crypto/ecc/bn254/fr"
 	"github.com/consensys/gnark/backend/plonk"
+	plonk_bn254 "github.com/consensys/gnark/backend/plonk/bn254"
 	"github.com/consensys/gnark/frontend"
 	"github.com/succinctlabs/sp1-recursion-gnark/sp1/babybear"
 )
@@ -56,3 +58,60 @@ func Verify(verifyCmdDataDir string, verifyCmdProof string, verifyCmdVkeyHash st
 	err = plonk.Verify(proof, vk, publicWitness)
 	return err
 }
+
+func VerifySolidity(verifyCmdDataDir string, verifyCmdProof string, verifyCmdVkeyHash string, verifyCmdCommitedValuesDigest string) error {
+	// Sanity check the required arguments have been provided.
+	if verifyCmdDataDir == "" {
+		panic("--data is required")
+	}
+
+	// Decode the proof.
+	proofDecodedBytes, err := hex.DecodeString(verifyCmdProof)
+	if err != nil {
+		panic(err)
+	}
+
+	// Proof contains 768 bytes worth of initial elements, followed by 32 bytes x nbCommits, followed by 64 bytes x nbCommits
+	nbCommits := (len(proofDecodedBytes) - 768) / 32 / 3;
+
+	proof_bn254 := plonk_bn254.UnmarshalSolidity(proofDecodedBytes, nbCommits) 
+
+	// Read the verifier key.
+	vkFile, err := os.Open(verifyCmdDataDir + "/" + vkPath)
+	if err != nil {
+		panic(err)
+	}
+	var vk plonk_bn254.VerifyingKey
+	_, err = vk.ReadFrom(vkFile)
+	if err != nil {
+		panic(err)
+	}
+
+	// Compute the public witness.
+	circuit := Circuit{
+		Vars:                 []frontend.Variable{},
+		Felts:                []babybear.Variable{},
+		Exts:                 []babybear.ExtensionVariable{},
+		VkeyHash:             verifyCmdVkeyHash,
+		CommitedValuesDigest: verifyCmdCommitedValuesDigest,
+	}
+	witness, err := frontend.NewWitness(&circuit, ecc.BN254.ScalarField())
+	if err != nil {
+		panic(err)
+	}
+	publicWitness, err := witness.Public()
+	if err != nil {
+		panic(err)
+	}
+
+	var witness_vec fr.Vector
+	if value, ok := publicWitness.Vector().(fr.Vector); ok {
+		witness_vec = value
+	} else {
+		panic("witness is not a vector")
+	}
+
+	// Verify proof.
+	err = plonk_bn254.Verify(&proof_bn254, &vk, witness_vec)
+	return err
+}

recursion/gnark-ffi/src/ffi/native.rs

@@ -69,6 +69,35 @@ pub fn verify_plonk_bn254(
     }
 }
 
+pub fn verify_plonk_bn254_solidity(
+    data_dir: &str,
+    proof: &str,
+    vkey_hash: &str,
+    committed_values_digest: &str,
+) -> Result<(), String> {
+    let data_dir = CString::new(data_dir).expect("CString::new failed");
+    let proof = CString::new(proof).expect("CString::new failed");
+    let vkey_hash = CString::new(vkey_hash).expect("CString::new failed");
+    let committed_values_digest =
+        CString::new(committed_values_digest).expect("CString::new failed");
+
+    let err_ptr = unsafe {
+        VerifyPlonkBn254Solidity(
+            data_dir.as_ptr() as *mut c_char,
+            proof.as_ptr() as *mut c_char,
+            vkey_hash.as_ptr() as *mut c_char,
+            committed_values_digest.as_ptr() as *mut c_char,
+        )
+    };
+    if err_ptr.is_null() {
+        Ok(())
+    } else {
+        // Safety: The error message is returned from the go code and is guaranteed to be valid.
+        let err = unsafe { CString::from_raw(err_ptr) };
+        Err(err.into_string().unwrap())
+    }
+}
+
 pub fn test_plonk_bn254(witness_json: &str, constraints_json: &str) {
     unsafe {
         let witness_json = CString::new(witness_json).expect("CString::new failed");