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ECC アルゴリズムの暗号化と復号化をテストしたい。

私はコードを書く:

  • 鍵ペア (公開鍵と秘密鍵) を生成 ---> それらをファイルに書き込みます (安全ではないかもしれませんが、テストしただけです)。

  • 次に、公開鍵を使用して文字列を暗号化します（Javaで書く）

  • 次に、暗号化された文字列を取得し、Android で復号化を試みます (秘密鍵を使用)

これが私のコードです：

  1. Java で文字列を暗号化します。

    /// generate key pair
ECNamedCurveParameterSpec spec = ECNamedCurveTable.getParameterSpec("prime256v1");
try 
{
    KeyPairGenerator g = KeyPairGenerator.getInstance("ECDSA",BouncyCastleProvider.PROVIDER_NAME);
    g.initialize(spec, new SecureRandom());
    KeyPair keyPair = g.generateKeyPair();
    privateKey = keyPair.getPrivate();
    publicKey = keyPair.getPublic();
    System.out.println("PublicKey:"+publicKey+"\n");
    System.out.println("PrivateKey:"+privateKey+"\n");

} 
catch (Exception e) 
{
    e.printStackTrace();
}
 try {
    Cipher c = Cipher.getInstance("ECIES",BouncyCastleProvider.PROVIDER_NAME);
    c.init(Cipher.ENCRYPT_MODE,publicKey);
    encodeBytes = c.doFinal(origin.getBytes());
    String encrypt = Base64.getEncoder().encodeToString(encodeBytes);
    System.out.println(encrypt);
} catch (Exception e) {
    e.printStackTrace();
}

私の出力暗号化文字列は次のようになります。

BB9Y4sKPbp28y7+FnpGnLGz5aTjD58GiIcXgjnNC4nXlUiqlHVVPc4K+ovlK5HK+Hz1Qps4ZWH9VdoYvm6VE36aEqvy53lJFnANDVpqAKuDUUaqEUrIQgF/TXFCFO22Il411atDsNhvJC3eRXbREL14duQbF8xjnLjru6WLN6GDYAQ==

そして、これが私の秘密鍵です

-----BEGIN PRIVATE KEY-----
MIGTAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBHkwdwIBAQQgCybVICafKcZiEmGNw+Pj/FfL6GMgDc94/E0zJ/EKgdGgCgYIKoZIzj0DAQehRANCAATRTcV/M0OJE94qlZM7VksMOw35fcuGSxejdgzbyYllWtlIQw9gYhKPZx6t/PVOEOec4DyZq2XwaoNxBxWRboL1
-----END PRIVATE KEY-----

  1. Android で文字列を復号化する

    encodeBytes = Base64.decode(encrypted_string_above,Base64.DEFAULT);
try
        {
            KeyFactory factory = KeyFactory.getInstance("ECDSA", "SC");

            String state;
            state = Environment.getExternalStorageState();
            File root = Environment.getExternalStorageDirectory();
            File dir = new File(root.getAbsolutePath()+"/disk");
            privateKeyFromFile = generatePrivateKey(factory,dir+"/private.pem");

            Cipher c = Cipher.getInstance("ECIES","SC");
            c.init(Cipher.DECRYPT_MODE,privateKeyFromFile);
            decodeBytes = c.doFinal(encodeBytes);
            String deCrypt = new String(decodeBytes,"UTF-8");


            txtHiden.setText(deCrypt);
            Toast.makeText(activity, deCrypt, Toast.LENGTH_SHORT).show();
        }
        catch (Exception ex)
        {
            ex.printStackTrace();
        }

しかし、私のコードは復号化に成功していません。問題があります:

  10-03 00:52:18.264 28656-28656/com.example.napoleon.luanvana W/System.err: org.spongycastle.jcajce.provider.util.BadBlockException: unable to process block
  10-03 00:52:18.264 28656-28656/com.example.napoleon.luanvana W/System.err:     at org.spongycastle.jcajce.provider.asymmetric.ec.IESCipher.engineDoFinal(IESCipher.java:476)
  10-03 00:52:18.264 28656-28656/com.example.napoleon.luanvana W/System.err:     at javax.crypto.Cipher.doFinal(Cipher.java:2056)
  10-03 00:52:18.264 28656-28656/com.example.napoleon.luanvana W/System.err:     at com.example.napoleon.luanvana.MessageFragment$3.onClick(MessageFragment.java:156)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at android.view.View.performClick(View.java:6213)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at android.widget.TextView.performClick(TextView.java:11074)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at android.view.View$PerformClick.run(View.java:23645)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at android.os.Handler.handleCallback(Handler.java:751)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:95)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at android.os.Looper.loop(Looper.java:154)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:6692)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1468)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1358)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err: Caused by: org.spongycastle.crypto.InvalidCipherTextException: unable to recover ephemeral public key: Sender's public key has invalid point encoding 0x51
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at org.spongycastle.crypto.engines.IESEngine.processBlock(IESEngine.java:409)
  10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at org.spongycastle.jcajce.provider.asymmetric.ec.IESCipher.engineDoFinal(IESCipher.java:472)
 10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     ... 12 more
 10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err: Caused by: java.io.IOException: Sender's public key has invalid point encoding 0x51
 10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at org.spongycastle.crypto.parsers.ECIESPublicKeyParser.readKey(ECIESPublicKeyParser.java:46)
 10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     at org.spongycastle.crypto.engines.IESEngine.processBlock(IESEngine.java:405)
 10-03 00:52:18.265 28656-28656/com.example.napoleon.luanvana W/System.err:     ... 13 more

おそらく間違ったエンコード/デコード文字列が原因だと思います-バイト-Base64

(Enctypt side)String encrypt = Base64.getEncoder().encodeToString(encodeBytes);
(Decrypt side): encodeBytes = Base64.decode(encrypted_string_above,Base64.DEFAULT);

しかし、私はこの問題についてあまり経験がありません。

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