ブラウザでRSA暗号化したデータをサーバで復号する（Angular + JSEncrypt、Spring MVC）【前編】

package com.example.demo;

public class EchoParam {

	private String email;

	private String password;

	public String getEmail() {
		return email;
	}

	public void setEmail(String email) {
		this.email = email;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}
}

package com.example.demo;

import java.io.FileInputStream;
import java.io.IOException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.Security;
import java.security.spec.KeySpec;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Base64;

import javax.crypto.Cipher;

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class EchoController {

	public EchoController() {
		Security.addProvider(new BouncyCastleProvider());
	}

	// 復号しないエコー
	@RequestMapping(path = "/echo")
	public EchoParam echo(@RequestBody EchoParam param) throws Exception {
		return param;
	}

	// 復号するエコー
	@RequestMapping(path = "/decrypted_echo")
	public EchoParam decryptedEcho(@RequestBody EchoParam param) throws Exception {

		String email = param.getEmail();
		String password = param.getPassword();

		System.out.println(email);
		System.out.println(password);

		byte[] b64DecodedPassword = Base64.getDecoder().decode(password);
        byte[] decrypted = decrypt(b64DecodedPassword);

        System.out.print("DECRYPTED: " + new String(decrypted));

		EchoParam ret = new EchoParam();
		ret.setEmail(email);
		ret.setPassword(new String(decrypted));

		return ret;
	}

    // 秘密鍵で暗号データを復号
    public byte[] decrypt(byte[] source) throws Exception {
        byte[] keyData = readKeyFile("private_key.pk8");
        KeySpec keyspec = new PKCS8EncodedKeySpec(keyData);
        KeyFactory keyfactory = KeyFactory.getInstance("RSA");
        Key privateKey = keyfactory.generatePrivate(keyspec);
        Cipher cipher = Cipher.getInstance("RSA//None/PKCS1PADDING", "BC");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(source);
    }

    // 秘密鍵ファイルprivate_key.derを読み込み
    private static byte[] readKeyFile(String filename) throws IOException {
        byte[] data = null;
        FileInputStream in = new FileInputStream(filename);
        data = new byte[in.available()];
        in.read(data);
        in.close();
        return data;
    }
}

		<dependency>
			<groupId>org.bouncycastle</groupId>
			<artifactId>bcprov-jdk15on</artifactId>
			<version>1.62</version>
		</dependency>