Merge pull request #170 from 0xPolygonHermez/feature/reduce-blobdata

Feature/reduce blobdata

package.json

@@ -11,7 +11,7 @@
     "test:blockinfo": "npx mocha ./test/processor.test.js --blockinfo",
     "test:selfdestruct": "npx mocha ./test/processor.test.js --selfdestruct",
     "eslint": "npx eslint 'src/**/**.js' 'test/**/**.test.js' && npx eslint tools",
-    "eslint:fix": "npx 'eslint src/**/**.js' 'test/**/**.test.js' --fix  && npx eslint tools --fix",
+    "eslint:fix": "npx eslint 'src/**/**.js' 'test/**/**.test.js' --fix && npx eslint tools --fix",
     "test:update": "./tools/update-tests/update-tests.sh",
     "test:database": "npx mocha ./test/database.test.js",
     "build:inputs": "npx mocha ./test/processor.test.js --update --geninputs && npx mocha ./test/processor.test.js --etrog --update --geninputs"

src/blob-inner/blob-processor.js

@@ -13,7 +13,7 @@ const getKzg = require('./kzg-utils');
 const {
     isHex, computeBlobAccInputHash, computeBlobL2HashData,
     computeBatchL2HashData, computeBatchAccInputHash, computeBlobDataFromBatches, parseBlobData,
-    computeVersionedHash,
+    computeVersionedHash, reduceBlobData,
 } = require('./blob-utils');
 const blobConstants = require('./blob-constants');
 
@@ -259,10 +259,11 @@ module.exports = class BlobProcessor {
             // blobL2HashData not used
             this.blobL2HashData = Constants.ZERO_BYTES32;
             // compute kzg data
-            this.kzgCommitment = this.kzg.blobToKzgCommitment(this.blobData);
+            const reducedBlobData = reduceBlobData(this.blobData);
+            this.kzgCommitment = this.kzg.blobToKzgCommitment(reducedBlobData);
             this.versionedHash = computeVersionedHash(this.kzgCommitment);
             this.pointZ = await this.kzg.computePointZ(this.kzgCommitment, this.blobData);
-            const { proof, pointY } = this.kzg.computeKzgProof(this.blobData, this.pointZ);
+            const { proof, pointY } = this.kzg.computeKzgProof(reducedBlobData, this.pointZ);
             this.pointY = pointY;
             this.kzgProof = proof;
         } else {

src/blob-inner/blob-utils.js

@@ -351,6 +351,24 @@ function parseBlobData(blobData, blobType) {
     return { isInvalid, batches };
 }
 
+/**
+ * Apply mod FrBLS12381 to each element in blobData
+ * @param {String} _blobData blob data
+ * @returns {String} - blobData with each element % FrBLA12_381
+ */
+function reduceBlobData(_blobData) {
+    const blobData = _blobData.startsWith('0x') ? _blobData.slice(2) : _blobData;
+    let blobDataReduced = '0x';
+
+    for (let i = 0; i < blobConstants.FIELD_ELEMENTS_PER_BLOB; i++) {
+        const fieldBlobData = Scalar.e(`0x${blobData.slice(i * (blobConstants.BYTES_PER_FIELD_ELEMENT * 2), (i + 1) * (blobConstants.BYTES_PER_FIELD_ELEMENT * 2))}`);
+        const final = (Scalar.mod(fieldBlobData, frBLS12381.p)).toString(16).padStart(blobConstants.BYTES_PER_FIELD_ELEMENT * 2, '0');
+        blobDataReduced += final;
+    }
+
+    return blobDataReduced;
+}
+
 module.exports = {
     isHex,
     computeBlobAccInputHash,
@@ -363,4 +381,5 @@ module.exports = {
     computeBlobDataFromBatches,
     parseBlobData,
     computeVersionedHash,
+    reduceBlobData,
 };

test/blob-inner/blob-utils.test.js

@@ -1,17 +1,51 @@
+const fs = require('fs');
+const path = require('path');
+const { argv } = require('yargs');
 const { expect } = require('chai');
 
 const {
     utils,
 } = require('../../index').blobInner;
+const { pathTestVectors } = require('../helpers/test-utils');
 
 // eslint-disable-next-line prefer-arrow-callback
 describe('blob utils', async function () {
+    let testVectors;
+    let update;
+
+    const pathReduceBlobTests = path.join(pathTestVectors, 'blob-inner/blob-reduce-data.json');
+
+    before(async () => {
+        testVectors = JSON.parse(fs.readFileSync(pathReduceBlobTests));
+
+        update = (argv.update === true);
+    });
+
     it('computeVersionedHash', async () => {
-        const expectedValue = '0x01ef9c6c1dae51f6f666f0b8633e81101fa03033830366d19c56401313422502';
+        const expectedValue = '0x017c04f3aff3266e4df00b2643a329439ee56323ba9fbe1aedac75b5b0bc759d';
 
         const kzgCommitment = '0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d493471dcc4de8dec75d7aab85b567b6ccd41a';
         const versionedHash = utils.computeVersionedHash(kzgCommitment);
 
         expect(versionedHash).to.be.equal(expectedValue);
     });
+
+    it('reduce blob', async () => {
+        for (let i = 0; i < testVectors.length; i++) {
+            const {
+                blobData,
+                expectedBlobDataReduced,
+            } = testVectors[i];
+
+            const reducedBlob = utils.reduceBlobData(blobData);
+
+            if (!update) {
+                expect(reducedBlob).to.be.equal(expectedBlobDataReduced);
+            } else {
+                testVectors[i].expectedBlobDataReduced = reducedBlob;
+
+                fs.writeFileSync(pathReduceBlobTests, JSON.stringify(testVectors, null, 2));
+            }
+        }
+    });
 });