【Java×金融API】セキュアな金融システムを自作！JWT認証×暗号化×HTTPSで堅牢なAPIを構築

[ユーザー] → [Spring Boot API] → [データベース]  
                      ↓  
            [JWT認証 + HTTPS + AES暗号化]

<dependency>
  <groupId>io.jsonwebtoken</groupId>
  <artifactId>jjwt</artifactId>
  <version>0.9.1</version>
</dependency>

import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
import java.util.Date;

public class JwtUtil {
    private static final String SECRET_KEY = "secret123";

    public static String generateToken(String username) {
        return Jwts.builder()
            .setSubject(username)
            .setIssuedAt(new Date())
            .setExpiration(new Date(System.currentTimeMillis() + 86400000))
            .signWith(SignatureAlgorithm.HS256, SECRET_KEY)
            .compact();
    }
}

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class AesUtil {
    private static final String key = "1234567890123456";

    public static String encrypt(String data) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
        return Base64.getEncoder().encodeToString(cipher.doFinal(data.getBytes()));
    }

    public static String decrypt(String encrypted) throws Exception {
        SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        return new String(cipher.doFinal(Base64.getDecoder().decode(encrypted)));
    }
}

server.port=8443
server.ssl.key-store=classpath:keystore.p12
server.ssl.key-store-password=yourpassword
server.ssl.keyStoreType=PKCS12
server.ssl.keyAlias=tomcat

src/
├─ JwtUtil.java
├─ AesUtil.java
├─ AuthController.java
├─ application.properties
└─ keystore.p12