Java技術を活用した契約印章真贋判定の妥当性に関する分析と事例共有

import java.security.*;

public class ContractSigning {
    public static void main(String[] args) throws Exception {
        // 生成密钥对
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(2048);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        
        // 生成签名
        Signature signature = Signature.getInstance("SHA256withRSA");
        signature.initSign(keyPair.getPrivate());
        String contractData = "这是一份合同";
        signature.update(contractData.getBytes());
        byte[] signBytes = signature.sign();
        
        // 验证签名
        Signature verification = Signature.getInstance("SHA256withRSA");
        verification.initVerify(keyPair.getPublic());
        verification.update(contractData.getBytes());
        boolean isVerified = verification.verify(signBytes);
        
        System.out.println("合同签名验证结果：" + isVerified);
    }
}

import org.hyperledger.fabric.sdk.*;
import org.hyperledger.fabric.sdk.exception.InvalidArgumentException;
import org.hyperledger.fabric.sdk.exception.ProposalException;

public class ContractBlockchain {
    public static void main(String[] args) throws Exception {
        // 连接到Fabric网络
        HFClient client = HFClient.createNewInstance();
        Channel channel = client.newChannel("contract-channel");
        Peer peer = client.newPeer("peer0.org1.example.com", "grpc://localhost:7051");
        channel.addPeer(peer);
        
        // 查询区块链上合同的哈希值
        QueryByChaincodeRequest queryRequest = client.newQueryProposalRequest();
        ChaincodeID contractChaincodeID = ChaincodeID.newBuilder()
                .setName("contract-chaincode")
                .setVersion("1.0")
                .setPath("github.com/hyperledger/fabric/examples/chaincode/go/contract")
                .build();
        queryRequest.setChaincodeID(contractChaincodeID);
        queryRequest.setFcn("getContractHash");
        queryRequest.setArgs(new String[] {"合同ID"});
        ChaincodeResponse response = channel.queryByChaincode(queryRequest);
        String contractHash = new String(response.getChaincodeActionResponsePayload());
        
        // 比对合同哈希值
        String originalContractHash = "原始合同哈希值";
        boolean isVerified = contractHash.equals(originalContractHash);
        
        System.out.println("合同哈希值验证结果：" + isVerified);
    }
}