Java实现合同公章真伪鉴别的最佳实践与策略

import java.security.*;

public class SignatureExample {

    public static byte[] signData(byte[] data, PrivateKey privateKey) throws Exception {
        Signature signature = Signature.getInstance("SHA256withRSA");
        signature.initSign(privateKey);
        signature.update(data);
        return signature.sign();
    }

    public static boolean verifySignature(byte[] data, byte[] publicKey, byte[] signature) throws Exception {
        Signature sig = Signature.getInstance("SHA256withRSA");
        PublicKey pubKey = KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(publicKey));
        sig.initVerify(pubKey);
        sig.update(data);
        return sig.verify(signature);
    }
}

import org.web3j.abi.datatypes.Address;

import org.web3j.crypto.Credentials;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.http.HttpService;
import org.web3j.protocol.core.methods.response.TransactionReceipt;
import org.web3j.tuples.generated.Tuple3;
import org.web3j.tx.gas.DefaultGasProvider;

public class BlockchainExample {

    public static String verifyContractSeal(String contractHash, String sealAddress) throws Exception {
        Web3j web3 = Web3j.build(new HttpService("https://ropsten.infura.io/v3/<your-infura-project-id>"));
        Credentials credentials = Credentials.create("<your-private-key>");

        Contract contract = Contract.load("<contract-address>", web3, credentials, new DefaultGasProvider());

        TransactionReceipt receipt = contract.verifySeal(new Address(sealAddress), contractHash).send();
        
        Tuple3<Boolean, String, BigInteger> result = contract.getSealResult(contractHash, new Address(sealAddress)).send();
        
        if(result.getValue1())
          return "合同公章真实有效";
        else
          return "合同公章无效";
    }
}

import java.nio.file.*;
import java.security.*;

public class KeyStoreExample {

    public static KeyStore loadKeyStore(String keystorePath, String keystorePassword) throws Exception {
        Path path = Paths.get(keystorePath);
        KeyStore keystore = KeyStore.getInstance("JKS");
        keystore.load(Files.newInputStream(path), keystorePassword.toCharArray());
        return keystore;
    }

    public static void saveKeyStore(KeyStore keystore, String keystorePath, String keystorePassword) throws Exception {
        Path path = Paths.get(keystorePath);
        keyStore.store(Files.newOutputStream(path), keystorePassword.toCharArray());
    }
}

import java.util.logging.*;

public class AccessControlExample {

    private static final Logger logger = Logger.getLogger(AccessControlExample.class.getName());

    public static void verifyContractSeal(String contractHash, String sealAddress) throws Exception {
        // 检查用户权限
        if (!checkUserRole("ContractVerifier")) {
            logger.severe("权限不足，无法验证合同公章");
            return;
        }

        // 执行公章验证逻辑
        try {
            String result = BlockchainExample.verifyContractSeal(contractHash, sealAddress);
            logger.info("合同公章验证结果：" + result);
        } catch (Exception e) {
            logger.severe("合同公章验证出现异常：" + e.getMessage());
        }

        // 记录日志
        logger.info("用户 " + getCurrentUserName() + " 验证了合同公章");
    }

    private static boolean checkUserRole(String role) {
        // 检查用户角色是否拥有指定权限
        return // check user role
    }

    private static String getCurrentUserName() {
        // 获取当前登录用户的用户名
        return // current user name
    }
}