chore: push proof splitting helpers into bb.js (#8795)

bb.js doesn't have any utilities for manipulating proofs for verifying public inputs, feeding proofs into the smart contract, etc. This pushes the utilities in the noir repo into bb.js.
AztecProtocol · Sep 27, 2024 · 9aa58e3 · 9aa58e3
1 parent ed43ebd
commit 9aa58e3
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Showing 4 changed files with 89 additions and 52 deletions.
diff --git a/barretenberg/ts/src/index.ts b/barretenberg/ts/src/index.ts
@@ -8,3 +8,4 @@ export {
   UltraHonkBackend,
 } from './barretenberg/index.js';
 export { RawBuffer, Fr } from './types/index.js';
+export { splitHonkProof, reconstructHonkProof } from './proof/index.js';
diff --git a/barretenberg/ts/src/proof/index.ts b/barretenberg/ts/src/proof/index.ts
@@ -0,0 +1,64 @@
+// Buffers are prepended with their size. The size takes 4 bytes.
+const serializedBufferSize = 4;
+const fieldByteSize = 32;
+const publicInputOffset = 3;
+const publicInputsOffsetBytes = publicInputOffset * fieldByteSize;
+
+export function splitHonkProof(proofWithPublicInputs: Uint8Array): { publicInputs: Uint8Array; proof: Uint8Array } {
+  const proofAsStrings = deflattenFields(proofWithPublicInputs.slice(4));
+
+  const numPublicInputs = Number(proofAsStrings[1]);
+
+  // Account for the serialized buffer size at start
+  const publicInputsOffset = publicInputsOffsetBytes + serializedBufferSize;
+  // Get the part before and after the public inputs
+  const proofStart = proofWithPublicInputs.slice(0, publicInputsOffset);
+  const publicInputsSplitIndex = numPublicInputs * fieldByteSize;
+  const proofEnd = proofWithPublicInputs.slice(publicInputsOffset + publicInputsSplitIndex);
+  // Construct the proof without the public inputs
+  const proof = new Uint8Array([...proofStart, ...proofEnd]);
+
+  // Fetch the number of public inputs out of the proof string
+  const publicInputs = proofWithPublicInputs.slice(publicInputsOffset, publicInputsOffset + publicInputsSplitIndex);
+
+  return {
+    proof,
+    publicInputs,
+  };
+}
+
+export function reconstructHonkProof(publicInputs: Uint8Array, proof: Uint8Array): Uint8Array {
+  const proofStart = proof.slice(0, publicInputsOffsetBytes + serializedBufferSize);
+  const proofEnd = proof.slice(publicInputsOffsetBytes + serializedBufferSize);
+
+  // Concatenate publicInputs and proof
+  const proofWithPublicInputs = Uint8Array.from([...proofStart, ...publicInputs, ...proofEnd]);
+
+  return proofWithPublicInputs;
+}
+
+function deflattenFields(flattenedFields: Uint8Array): string[] {
+  const publicInputSize = 32;
+  const chunkedFlattenedPublicInputs: Uint8Array[] = [];
+
+  for (let i = 0; i < flattenedFields.length; i += publicInputSize) {
+    const publicInput = flattenedFields.slice(i, i + publicInputSize);
+    chunkedFlattenedPublicInputs.push(publicInput);
+  }
+
+  return chunkedFlattenedPublicInputs.map(uint8ArrayToHex);
+}
+
+function uint8ArrayToHex(buffer: Uint8Array): string {
+  const hex: string[] = [];
+
+  buffer.forEach(function (i) {
+    let h = i.toString(16);
+    if (h.length % 2) {
+      h = '0' + h;
+    }
+    hex.push(h);
+  });
+
+  return '0x' + hex.join('');
+}
diff --git a/noir/noir-repo/tooling/noir_js_backend_barretenberg/src/backend.ts b/noir/noir-repo/tooling/noir_js_backend_barretenberg/src/backend.ts
@@ -1,8 +1,14 @@
 import { acirToUint8Array } from './serialize.js';
 import { Backend, CompiledCircuit, ProofData, VerifierBackend } from '@noir-lang/types';
-import { deflattenFields } from './public_inputs.js';
-import { reconstructProofWithPublicInputs, reconstructProofWithPublicInputsHonk } from './verifier.js';
-import { BackendOptions, UltraPlonkBackend, UltraHonkBackend as UltraHonkBackendInternal } from '@aztec/bb.js';
+import { deflattenFields, flattenFieldsAsArray } from './public_inputs.js';
+import { reconstructProofWithPublicInputs } from './verifier.js';
+import {
+  BackendOptions,
+  reconstructHonkProof,
+  splitHonkProof,
+  UltraPlonkBackend,
+  UltraHonkBackend as UltraHonkBackendInternal,
+} from '@aztec/bb.js';
 import { decompressSync as gunzip } from 'fflate';
 
 // This is the number of bytes in a UltraPlonk proof
@@ -74,12 +80,6 @@ export class BarretenbergBackend implements Backend, VerifierBackend {
   }
 }
 
-// Buffers are prepended with their size. The size takes 4 bytes.
-const serializedBufferSize = 4;
-const fieldByteSize = 32;
-const publicInputOffset = 3;
-const publicInputsOffsetBytes = publicInputOffset * fieldByteSize;
-
 export class UltraHonkBackend implements Backend, VerifierBackend {
   // These type assertions are used so that we don't
   // have to initialize `api` in the constructor.
@@ -96,32 +96,16 @@ export class UltraHonkBackend implements Backend, VerifierBackend {
 
   async generateProof(compressedWitness: Uint8Array): Promise<ProofData> {
     const proofWithPublicInputs = await this.backend.generateProof(gunzip(compressedWitness));
-    const proofAsStrings = deflattenFields(proofWithPublicInputs.slice(4));
-
-    const numPublicInputs = Number(proofAsStrings[1]);
-
-    // Account for the serialized buffer size at start
-    const publicInputsOffset = publicInputsOffsetBytes + serializedBufferSize;
-    // Get the part before and after the public inputs
-    const proofStart = proofWithPublicInputs.slice(0, publicInputsOffset);
-    const publicInputsSplitIndex = numPublicInputs * fieldByteSize;
-    const proofEnd = proofWithPublicInputs.slice(publicInputsOffset + publicInputsSplitIndex);
-    // Construct the proof without the public inputs
-    const proof = new Uint8Array([...proofStart, ...proofEnd]);
-
-    // Fetch the number of public inputs out of the proof string
-    const publicInputsConcatenated = proofWithPublicInputs.slice(
-      publicInputsOffset,
-      publicInputsOffset + publicInputsSplitIndex,
-    );
-    const publicInputs = deflattenFields(publicInputsConcatenated);
+
+    const { proof, publicInputs: flatPublicInputs } = splitHonkProof(proofWithPublicInputs);
+    const publicInputs = deflattenFields(flatPublicInputs);
 
     return { proof, publicInputs };
   }
 
   async verifyProof(proofData: ProofData): Promise<boolean> {
-    const proof = reconstructProofWithPublicInputsHonk(proofData);
-
+    const flattenedPublicInputs = flattenFieldsAsArray(proofData.publicInputs);
+    const proof = reconstructHonkProof(flattenedPublicInputs, proofData.proof);
     return this.backend.verifyProof(proof);
   }
 
@@ -134,8 +118,9 @@ export class UltraHonkBackend implements Backend, VerifierBackend {
     proofData: ProofData,
     numOfPublicInputs: number,
   ): Promise<{ proofAsFields: string[]; vkAsFields: string[]; vkHash: string }> {
-    const proof = reconstructProofWithPublicInputsHonk(proofData);
-    return this.backend.generateRecursiveProofArtifacts(proof, numOfPublicInputs)
+    const flattenedPublicInputs = flattenFieldsAsArray(proofData.publicInputs);
+    const proof = reconstructHonkProof(flattenedPublicInputs, proofData.proof);
+    return this.backend.generateRecursiveProofArtifacts(proof, numOfPublicInputs);
   }
 
   async destroy(): Promise<void> {

diff --git a/noir/noir-repo/tooling/noir_js_backend_barretenberg/src/verifier.ts b/noir/noir-repo/tooling/noir_js_backend_barretenberg/src/verifier.ts
@@ -1,6 +1,10 @@
 import { ProofData } from '@noir-lang/types';
 import { flattenFieldsAsArray } from './public_inputs.js';
-import { BackendOptions, BarretenbergVerifier as BarretenbergVerifierInternal } from '@aztec/bb.js';
+import {
+  BackendOptions,
+  BarretenbergVerifier as BarretenbergVerifierInternal,
+  reconstructHonkProof,
+} from '@aztec/bb.js';
 
 export class BarretenbergVerifier {
   private verifier!: BarretenbergVerifierInternal;
@@ -39,29 +43,12 @@ export class UltraHonkVerifier {
 
   /** @description Verifies a proof */
   async verifyProof(proofData: ProofData, verificationKey: Uint8Array): Promise<boolean> {
-    const proof = reconstructProofWithPublicInputsHonk(proofData);
+    const flattenedPublicInputs = flattenFieldsAsArray(proofData.publicInputs);
+    const proof = reconstructHonkProof(flattenedPublicInputs, proofData.proof);
     return this.verifier.verifyUltrahonkProof(proof, verificationKey);
   }
 
   async destroy(): Promise<void> {
     await this.verifier.destroy();
   }
 }
-
-const serializedBufferSize = 4;
-const fieldByteSize = 32;
-const publicInputOffset = 3;
-const publicInputsOffsetBytes = publicInputOffset * fieldByteSize;
-
-export function reconstructProofWithPublicInputsHonk(proofData: ProofData): Uint8Array {
-  // Flatten publicInputs
-  const publicInputsConcatenated = flattenFieldsAsArray(proofData.publicInputs);
-
-  const proofStart = proofData.proof.slice(0, publicInputsOffsetBytes + serializedBufferSize);
-  const proofEnd = proofData.proof.slice(publicInputsOffsetBytes + serializedBufferSize);
-
-  // Concatenate publicInputs and proof
-  const proofWithPublicInputs = Uint8Array.from([...proofStart, ...publicInputsConcatenated, ...proofEnd]);
-
-  return proofWithPublicInputs;
-}