Java技术的合同公章真伪鉴别有效性分析与案例分享

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);
    }
}