Example With SHA-256 In Spring Boot#

In this example we will use SHA-256, there is a SHA-512 which use newer hashing algorithms and usually used in blockchain, but in require more bandwidth to store and transmit data. So in this example which is not blockchain I recommend we use SHA-256 because in recent It is lightweight and still secure for us.

Controller#

Let's create an controller with some apis as below:

Sha256Controller.java
package com.springboot.security.hash.app.controller;

import com.springboot.security.hash.app.model.DataRequest;
import com.springboot.security.hash.app.model.MatchDataRequest;
import com.springboot.security.hash.app.service.HashSha256Service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Sha256Controller {

    @Autowired
    private HashSha256Service hashSha256Service;

    @RequestMapping(method = RequestMethod.POST, path = "v1/cipher/hash/sha256", produces = MediaType.TEXT_PLAIN_VALUE)
    public ResponseEntity<String> hashSHA256(@RequestBody DataRequest inputData) {
        return new ResponseEntity<>(this.hashSha256Service.hashSHA256(inputData.getData()), HttpStatus.CREATED);
    }

    @RequestMapping(method = RequestMethod.POST, path = "v1/cipher/hash/sha256/check", produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Boolean> checkMatchSha256(@RequestBody MatchDataRequest inputData) {
        return new ResponseEntity<>(this.hashSha256Service.isSHA256Match(inputData.getRawData(), inputData.getHashedData()), HttpStatus.OK);
    }

}

We will need to create 2 simple models for request body as below. One is used for hashing data and the other one is used for checking raw data and hashed data.

DataRequest.java
package com.springboot.security.hash.app.model;

import org.springframework.lang.NonNull;

public class DataRequest {

    private String data;

    @NonNull
    public String getData() {
        return data;
    }

    public void setData(@NonNull String data) {
        this.data = data;
    }

}

MatchDataRequest.java
package com.springboot.security.hash.app.model;

public class MatchDataRequest {

    private String rawData;
    private String hashedData;

    public String getRawData() {
        return rawData;
    }

    public void setRawData(String rawData) {
        this.rawData = rawData;
    }

    public String getHashedData() {
        return hashedData;
    }

    public void setHashedData(String hashedData) {
        this.hashedData = hashedData;
    }
}

Then we also need to create a model that loads environment variables into a spring bean using @ConfigurationProperties as below.

HashConfigProperties.java
package com.springboot.security.hash.app.model;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties(prefix = "hash")
public class HashConfigProperties {

    private Sha256 sha256;

    public Sha256 getSha256() {
        return sha256;
    }

    public void setSha256(Sha256 sha256) {
        this.sha256 = sha256;
    }
}

Sha256.java
package com.springboot.security.hash.app.model;

public class Sha256 {

    private String salt;

    public String getSalt() {
        return salt;
    }

    public void setSalt(String salt) {
        this.salt = salt;
    }
}

Service#

In Spring Boot we don't need to add more any dependency to do the Hashing with SHA-256, we will use MessageDigest with hash algorithm is SHA-256 that Spring Boot provided. This class provide a method getInstance with input is the name of hash algorithm to create MessageDigest.
What is the Message Digest? More information.
Now let's create HashSha256Service and add two methods hashSHA256 and isSHA256Match below for hashing data and checking the hashed data with the given hashed by using MessageDigest.isEqual.

HashSha256Service.java
package com.springboot.security.hash.app.service;

import com.springboot.security.hash.app.model.HashConfigProperties;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.xml.bind.DatatypeConverter;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;

@Service
public class HashSha256Service {

    private static final String HASH_ALGORITHM_SHA_256 = "SHA-256";

    @Autowired
    private HashConfigProperties hashConfigProperties;

    public String hashSHA256(String data) {
        byte[] hash = this.hash(data);
        return DatatypeConverter.printHexBinary(hash);
    }

    public boolean isSHA256Match(String data, String hashedData) {
        byte[] digested = DatatypeConverter.parseHexBinary(hashedData);
        byte[] reHashData = this.hash(data);
        return MessageDigest.isEqual(digested, reHashData);
    }

    private byte[] hash(String data) {
        try {
            String dataWithSalt = hashConfigProperties.getSha256().getSalt().concat(data);
            MessageDigest messageDigest = MessageDigest.getInstance(HASH_ALGORITHM_SHA_256);
            return messageDigest.digest(dataWithSalt.getBytes(StandardCharsets.UTF_8));
        } catch (Exception ex) {
            throw new RuntimeException("Can not hash Data", ex);
        }
    }

}

Then we will hash the data together with the salt that we load from the application.yml into the HashConfigProperties component using @ConfigurationProperties. The Salt will be any string, see the example below.

application.yml
hash:  
    sha256:  
        salt: 70DD29E1BE48BBA013A2E7EDF6F10861F82DD9C9C0C2A1419C69D3CD74513452

Testing#

Now, run the Spring Boot project and try to call api v1/cipher/hash/sha256 for testing hasing data. Then you will receive the result as below

Then with the hash result above, we will use it to check with the original data by calling api v1/cipher/hash/sha256/check. Then you will see the original data and hashed data are matched.

Now let's try to change a single character in original data and check again with hashed data. Then you will see the api return failed.

Example With SHA-256 In Spring Boot#

Example With SHA-256 In Spring Boot#

Controller#

Service#

Testing#

See Also#

References#