diff --git a/src/utils.js b/src/utils.js
index bd1338e..ddc1dcf 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -21,6 +21,8 @@ const bigInt = require("big-integer");
 const Circuit = require("snarkjs/src/circuit");
 const bigInt2 = require("snarkjs/src/bigint");
 const hexifyBigInts = require("../tools/stringifybigint").hexifyBigInts;
+const unhexifyBigInts = require("../tools/stringifybigint").unhexifyBigInts;
+const stringifyBigInts = require("../tools/stringifybigint").stringifyBigInts;
 const unstringifyBigInts = require("../tools/stringifybigint").unstringifyBigInts;
 const stringifyBigInts2 = require("snarkjs/src/stringifybigint").stringifyBigInts;
 const unstringifyBigInts2 = require("snarkjs/src/stringifybigint").unstringifyBigInts;
@@ -75,9 +77,22 @@ function toSolidityInput(proof) {
     return hexifyBigInts(unstringifyBigInts(result));
 }
 
+function fromSolidityInput(proof) {
+    proof = unhexifyBigInts(proof);
+    const result = {
+        pi_a: [proof.pi_a[0], proof.pi_a[1], bigInt(1)],
+        pi_b: [[proof.pi_b[0][1], proof.pi_b[0][0]], [proof.pi_b[1][1], proof.pi_b[1][0]], [bigInt(1), bigInt(0)]],
+        pi_c: [proof.pi_c[0], proof.pi_c[1], bigInt(1)]
+    };
+    if (proof.publicSignals) {
+        result.publicSignals = proof.publicSignals;
+    }
+    return stringifyBigInts(proof);
+}
+
 function  genWitness(input, circuitJson) {
     const circuit = new Circuit(unstringifyBigInts2(circuitJson));
-    const witness = circuit.calculateWitness(input);
+    const witness = circuit.calculateWitness(unstringifyBigInts2(input));
     const publicSignals = witness.slice(1, circuit.nPubInputs + circuit.nOutputs + 1);
     return {witness, publicSignals};
 }
@@ -90,4 +105,4 @@ async function genWitnessAndProve(groth16, input, circuitJson, provingKey) {
     return result;
 }
 
-module.exports = {bigInt2BytesLE, bigInt2U32LE, toSolidityInput, genWitnessAndProve};
\ No newline at end of file
+module.exports = {bigInt2BytesLE, bigInt2U32LE, toSolidityInput, fromSolidityInput, genWitnessAndProve};
\ No newline at end of file
diff --git a/tools/stringifybigint.js b/tools/stringifybigint.js
index 01c7bc5..9a66c7a 100644
--- a/tools/stringifybigint.js
+++ b/tools/stringifybigint.js
@@ -22,6 +22,7 @@ const bigInt = require("big-integer");
 module.exports.stringifyBigInts = stringifyBigInts;
 module.exports.unstringifyBigInts = unstringifyBigInts;
 module.exports.hexifyBigInts = hexifyBigInts;
+module.exports.unhexifyBigInts = unhexifyBigInts;
 
 function stringifyBigInts(o) {
     if ((typeof(o) == "bigint") || (o instanceof bigInt))  {
@@ -73,3 +74,19 @@ function hexifyBigInts(o) {
         return o;
     }
 }
+
+function unhexifyBigInts(o) {
+    if ((typeof(o) == "string") && (/^0x[0-9a-fA-F]+$/.test(o)))  {
+        return bigInt(o);
+    } else if (Array.isArray(o)) {
+        return o.map(unhexifyBigInts);
+    } else if (typeof o == "object") {
+        const res = {};
+        for (let k in o) {
+            res[k] = unhexifyBigInts(o[k]);
+        }
+        return res;
+    } else {
+        return o;
+    }
+}