Use Java technology to determine the authenticity and legality of the official seal in the contract

Use Java technology to determine the authenticity and legality of the official seal in the contract

In the process of signing the contract, the authenticity and legality of the official seal are very important, because It verifies the reliability and legality of the contract. Using Java technology, we can write a program to determine the authenticity and legality of the official seal in the contract. Below is a sample code that demonstrates how to use Java for validation.

import java.io.FileInputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class ContractValidation {

    public static void main(String[] args) {
        String contractPath = "path/to/contract.pdf";
        String sealPath = "path/to/seal.png";
        
        try {
            byte[] contractHash = calculateHash(contractPath);
            byte[] sealHash = calculateHash(sealPath);
         
            boolean valid = verifyContract(contractHash, sealHash);
            
            if (valid) {
                System.out.println("公章验证通过，合同有效！");
            } else {
                System.out.println("公章验证失败，合同可能被篡改！");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }
    
    public static byte[] calculateHash(String filePath) throws IOException, NoSuchAlgorithmException {
        FileInputStream fis = new FileInputStream(filePath);
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        
        byte[] buffer = new byte[1024];
        int bytesRead;
        
        while ((bytesRead = fis.read(buffer)) != -1) {
            md.update(buffer, 0, bytesRead);
        }
        
        return md.digest();
    }
    
    public static boolean verifyContract(byte[] contractHash, byte[] sealHash) {
        // 比较合同哈希和公章哈希是否相等
        for (int i = 0; i < contractHash.length; i++) {
            if (contractHash[i] != sealHash[i]) {
                return false;
            }
        }
        
        return true;
    }
}

In the above code, we use the SHA-256 algorithm to calculate the hash value of the file. The hash value is a value that uniquely identifies the file content. First, we calculated the hash values ​​of the contract document and official seal document respectively through the calculateHash function. Then, we use the verifyContract function to compare the two hash values. If they are equal, we consider that the official seal verification is passed and the contract is valid.

It should be noted that this is just a simple sample code. In actual use, more factors need to be considered, such as file integrity, digital certificates, etc. At the same time, in order to ensure security, more reliable algorithms and strategies should be used.

To sum up, it is feasible to use Java technology to determine the authenticity and legality of the official seal in the contract. We can use Java to read files, calculate hash values ​​and other functions to verify the official seal during the contract signing process to ensure the reliability and legality of the contract.

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