FHEVM项目快速入门：测试全同态加密智能合约

前言

本文将详细介绍如何使用Zama的FHEVM库测试支持全同态加密(FHE)的智能合约。我们将从基础测试环境搭建开始，逐步实现加密状态变量的测试验证，帮助开发者掌握FHEVM的核心测试方法。

测试环境搭建

创建测试脚本

在项目test目录下创建FHECounter.ts文件，内容如下：

import { FHECounter, FHECounter__factory } from "../types";
import { FhevmType } from "@fhevm/hardhat-plugin";
import { HardhatEthersSigner } from "@nomicfoundation/hardhat-ethers/signers";
import { expect } from "chai";
import { ethers, fhevm } from "hardhat";

type Signers = {
  deployer: HardhatEthersSigner;
  alice: HardhatEthersSigner;
  bob: HardhatEthersSigner;
};

async function deployFixture() {
  const factory = (await ethers.getContractFactory("FHECounter")) as FHECounter__factory;
  const fheCounterContract = (await factory.deploy()) as FHECounter;
  const fheCounterContractAddress = await fheCounterContract.getAddress();

  return { fheCounterContract, fheCounterContractAddress };
}

describe("FHECounter", function () {
  let signers: Signers;
  let fheCounterContract: FHECounter;
  let fheCounterContractAddress: string;

  before(async function () {
    const ethSigners: HardhatEthersSigner[] = await ethers.getSigners();
    signers = { deployer: ethSigners[0], alice: ethSigners[1], bob: ethSigners[2] };
  });

  beforeEach(async () => {
    ({ fheCounterContract, fheCounterContractAddress } = await deployFixture());
  });

  it("should be deployed", async function () {
    console.log(`FHECounter has been deployed at address ${fheCounterContractAddress}`);
    expect(ethers.isAddress(fheCounterContractAddress)).to.eq(true);
  });
});

与传统测试的区别

1. 使用FHEVM兼容的智能合约FHECounter而非普通Counter
2. 测试逻辑相同但支持加密计算
3. 状态变量以加密形式存储和操作

基础测试验证

部署验证测试

运行测试命令：

npx hardhat test

预期输出：

  FHECounter
FHECounter has been deployed at address 0x7553CB9124f974Ee475E5cE45482F90d5B6076BC
    ✔ should be deployed


  1 passing (1ms)

加密状态变量测试

初始状态验证

it("encrypted count should be uninitialized after deployment", async function () {
  const encryptedCount = await fheCounterContract.getCount();
  expect(encryptedCount).to.eq(ethers.ZeroHash);
});

关键点：

• encryptedCount是十六进制字符串表示的FHEVM句柄
• 初始值为0x000...000表示未初始化状态
• 底层逻辑上等同于明文0

加密操作测试

增量操作测试

it("increment the counter by 1", async function () {
  // 验证初始状态
  const encryptedCountBeforeInc = await fheCounterContract.getCount();
  expect(encryptedCountBeforeInc).to.eq(ethers.ZeroHash);
  const clearCountBeforeInc = 0;

  // 加密操作数1
  const clearOne = 1;
  const encryptedOne = await fhevm
    .createEncryptedInput(fheCounterContractAddress, signers.alice.address)
    .add32(clearOne)
    .encrypt();

  // 执行增量操作
  const tx = await fheCounterContract
    .connect(signers.alice)
    .increment(encryptedOne.handles[0], encryptedOne.inputProof);
  await tx.wait();

  // 验证结果
  const encryptedCountAfterInc = await fheCounterContract.getCount();
  const clearCountAfterInc = await fhevm.userDecryptEuint(
    FhevmType.euint32,
    encryptedCountAfterInc,
    fheCounterContractAddress,
    signers.alice,
  );
  expect(clearCountAfterInc).to.eq(clearCountBeforeInc + clearOne);
});

技术要点：

1. 使用createEncryptedInput创建绑定到特定合约和用户的加密输入
2. 增量操作需要提供加密值和零知识证明
3. 使用userDecryptEuint解密结果验证

减量操作测试

it("decrement the counter by 1", async function () {
  // 加密操作数1
  const clearOne = 1;
  const encryptedOne = await fhevm
    .createEncryptedInput(fheCounterContractAddress, signers.alice.address)
    .add32(clearOne)
    .encrypt();

  // 先增1
  let tx = await fheCounterContract
    .connect(signers.alice)
    .increment(encryptedOne.handles[0], encryptedOne.inputProof);
  await tx.wait();

  // 再减1
  tx = await fheCounterContract
    .connect(signers.alice)
    .decrement(encryptedOne.handles[0], encryptedOne.inputProof);
  await tx.wait();

  // 验证结果
  const encryptedCountAfterDec = await fheCounterContract.getCount();
  const clearCountAfterDec = await fhevm.userDecryptEuint(
    FhevmType.euint32,
    encryptedCountAfterDec,
    fheCounterContractAddress,
    signers.alice,
  );
  expect(clearCountAfterDec).to.eq(0);
});

安全机制解析

1. 上下文绑定加密：加密值绑定到特定合约和用户，防止重用
2. 零知识证明：验证加密输入的完整性和真实性
3. 权限控制：通过FHE.allow()实现加密数据的访问控制

总结

通过本教程，您已经掌握了：

1. FHEVM测试环境搭建方法
2. 加密状态变量的初始化和验证
3. 加密操作的执行和结果验证
4. FHEVM的核心安全机制

这些知识为您开发更复杂的全同态加密智能合约奠定了坚实基础。下一步可以尝试部署到测试网络或探索更复杂的FHEVM功能。