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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,109 @@ | ||
| "use strict"; | ||
| var __importDefault = (this && this.__importDefault) || function (mod) { | ||
| return (mod && mod.__esModule) ? mod : { "default": mod }; | ||
| }; | ||
| Object.defineProperty(exports, "__esModule", { value: true }); | ||
| exports.verifyMerkleInclusion = void 0; | ||
| /* | ||
| Copyright 2023 The Sigstore Authors. | ||
| Licensed under the Apache License, Version 2.0 (the "License"); | ||
| you may not use this file except in compliance with the License. | ||
| You may obtain a copy of the License at | ||
| http://www.apache.org/licenses/LICENSE-2.0 | ||
| Unless required by applicable law or agreed to in writing, software | ||
| distributed under the License is distributed on an "AS IS" BASIS, | ||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| See the License for the specific language governing permissions and | ||
| limitations under the License. | ||
| */ | ||
| const crypto_1 = __importDefault(require("crypto")); | ||
| const error_1 = require("../../error"); | ||
| const RFC6962_LEAF_HASH_PREFIX = Buffer.from([0x00]); | ||
| const RFC6962_NODE_HASH_PREFIX = Buffer.from([0x01]); | ||
| function verifyMerkleInclusion(entry) { | ||
| const inclusionProof = entry.inclusionProof; | ||
| if (!inclusionProof) { | ||
| throw new error_1.VerificationError('tlog entry has no inclusion proof'); | ||
| } | ||
| const logIndex = BigInt(inclusionProof.logIndex); | ||
| const treeSize = BigInt(inclusionProof.treeSize); | ||
| if (logIndex < 0n || logIndex >= treeSize) { | ||
| throw new error_1.VerificationError('invalid inclusion proof index'); | ||
| } | ||
| // Figure out which subset of hashes corresponds to the inner and border | ||
| // nodes | ||
| const { inner, border } = decompInclProof(logIndex, treeSize); | ||
| if (inclusionProof.hashes.length !== inner + border) { | ||
| throw new error_1.VerificationError('invalid inclusion proof length'); | ||
| } | ||
| const innerHashes = inclusionProof.hashes.slice(0, inner); | ||
| const borderHashes = inclusionProof.hashes.slice(inner); | ||
| // The entry's hash is the leaf hash | ||
| const leafHash = hashLeaf(entry.canonicalizedBody); | ||
| // Chain the hashes belonging to the inner and border portions | ||
| const calculatedHash = chainBorderRight(chainInner(leafHash, innerHashes, logIndex), borderHashes); | ||
| // Calculated hash should match the root hash in the inclusion proof | ||
| return bufferEqual(calculatedHash, inclusionProof.rootHash); | ||
| } | ||
| exports.verifyMerkleInclusion = verifyMerkleInclusion; | ||
| // Breaks down inclusion proof for a leaf at the specified index in a tree of | ||
| // the specified size. The split point is where paths to the index leaf and | ||
| // the (size - 1) leaf diverge. Returns lengths of the bottom and upper proof | ||
| // parts. | ||
| function decompInclProof(index, size) { | ||
| const inner = innerProofSize(index, size); | ||
| const border = onesCount(index >> BigInt(inner)); | ||
| return { inner, border }; | ||
| } | ||
| // Computes a subtree hash for a node on or below the tree's right border. | ||
| // Assumes the provided proof hashes are ordered from lower to higher levels | ||
| // and seed is the initial hash of the node specified by the index. | ||
| function chainInner(seed, hashes, index) { | ||
| return hashes.reduce((acc, h, i) => { | ||
| if ((index >> BigInt(i)) & BigInt(1)) { | ||
| return hashChildren(h, acc); | ||
| } | ||
| else { | ||
| return hashChildren(acc, h); | ||
| } | ||
| }, seed); | ||
| } | ||
| // Computes a subtree hash for nodes along the tree's right border. | ||
| function chainBorderRight(seed, hashes) { | ||
| return hashes.reduce((acc, h) => hashChildren(h, acc), seed); | ||
| } | ||
| function innerProofSize(index, size) { | ||
| return (index ^ (size - BigInt(1))).toString(2).length; | ||
| } | ||
| // Counts the number of ones in the binary representation of the given number. | ||
| // https://en.wikipedia.org/wiki/Hamming_weight | ||
| function onesCount(x) { | ||
| return x.toString(2).split('1').length - 1; | ||
| } | ||
| // Hashing logic according to RFC6962. | ||
| // https://datatracker.ietf.org/doc/html/rfc6962#section-2 | ||
| function hashChildren(left, right) { | ||
| const hasher = crypto_1.default.createHash('sha256'); | ||
| hasher.update(RFC6962_NODE_HASH_PREFIX); | ||
| hasher.update(left); | ||
| hasher.update(right); | ||
| return hasher.digest(); | ||
| } | ||
| function hashLeaf(leaf) { | ||
| const hasher = crypto_1.default.createHash('sha256'); | ||
| hasher.update(RFC6962_LEAF_HASH_PREFIX); | ||
| hasher.update(leaf); | ||
| return hasher.digest(); | ||
| } | ||
| function bufferEqual(a, b) { | ||
| try { | ||
| return crypto_1.default.timingSafeEqual(a, b); | ||
| } | ||
| catch { | ||
| /* istanbul ignore next */ | ||
| return false; | ||
| } | ||
| } |
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