java - Java RSA 暗号化/復号化の問題

Question

BouncyCastle Java API で RSA を使用してデータを暗号化/復号化できるコードが必要です。実装しましたが、次の例外が発生しました：

javax.crypto.BadPaddingException: unknown block type in following code.

コードは次のとおりです。

public class rsa {

private PrivateKey rsaPrivate;
private PublicKey rsapublic;
private Cipher cipher=null;
private  final String ALGORITHM = "RSA";
private  final String PROVIDER = "BC";

public rsa() throws NoSuchAlgorithmException, NoSuchPaddingException, NoSuchProviderException
{
this.init();    
}

public void init() throws NoSuchAlgorithmException, NoSuchPaddingException, NoSuchProviderException
{
    Security.addProvider(new BouncyCastleProvider());
    KeyPairGenerator keyGen = KeyPairGenerator.getInstance(ALGORITHM,PROVIDER);  
    keyGen.initialize(1024);  
    KeyPair keyPair = keyGen.generateKeyPair();  
    this.setRsaPrivate(keyPair.getPrivate())  ;  
    this.setRsapublic(keyPair.getPublic());  
}


     ********* Getter**(){} AND **Setter**(){} methods are removed **********


public String encryption(String Message) throws InvalidKeyException,IllegalBlockSizeException,
                                                BadPaddingException, NoSuchAlgorithmException, 
                                                NoSuchProviderException, NoSuchPaddingException, 
                                                UnsupportedEncodingException
{
    cipher=Cipher.getInstance("RSA/ECB/PKCS1Padding",PROVIDER);
    cipher.init(Cipher.ENCRYPT_MODE,this.getRsapublic());  
    byte[] encryptedMsg = cipher.doFinal(Message.getBytes());  
    return  new String(encryptedMsg); 
}


public String decryption(String encryptedMsg) throws InvalidKeyException, IllegalBlockSizeException,
                                                    BadPaddingException, UnsupportedEncodingException,
                                                    NoSuchAlgorithmException, NoSuchProviderException,
                                                    NoSuchPaddingException
{ 

    Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding",PROVIDER);
    cipher.init(Cipher.DECRYPT_MODE,this.getRsaPrivate());
    byte[] dectyptedText = cipher.doFinal(encryptedMsg.getBytes()); 
    return new String(dectyptedText);
}

public static void main(String args[]) throws Exception
{
    rsa r=new rsa();
    System.out.println("Test1 encrypt normal: "+Base64.encodeBase64String(r.encryption("123456").getBytes()));
    System.out.println("Test2 decrypt normal: "+r.decryption(r.encryption("123456")));
}
}

* OUTPUT ** : Test1 暗号化通常:

uXpqwit/bNH9GUpCPoL+7pjVhOYfQT95ZHCHRoBntfYuKhV9cnQUeSe2df1oTdp45JZFG9uohGssnMP2‌​BP9Lm6+xwxprQi7t2n3mjoLOTj+e+2rc2/hKlwhoHIpEmO6O7SWeQh+05PIhP9YnPOM97VKGfu/oXFj12‌​84pC9s0smM= Exception in thread "main" javax.crypto.BadPaddingException: unknown block type at org.bouncycastle.jce.provider.JCERSACipher.engineDoFinal(ソース不明) javax.crypto.Cipher.doFinal(DashoA13*..) com.crypto.rsa.decryption(rsa.java:85) >>>>>>>>>>>>>>>>>>> >>>ここでメソッド復号化でエラーが発生しましたcipher.doFinal(encryptedMsg.getBytes())

最後に出力を取得しました

public class RSAUTIL

{

String ALGORITHM_USED = "RSA";
String PROVIDER = "BC";
private KeyPair key; 
public RSAUTIL() throws NoSuchAlgorithmException
{
    this.init();
    this.generateKey();
}

public void init()
{
    Security.addProvider(new BouncyCastleProvider());

}

public KeyPair generateKey() throws NoSuchAlgorithmException
{
    KeyPairGenerator keyGen = null;
    try { 
        keyGen = KeyPairGenerator.getInstance(ALGORITHM_USED, PROVIDER);
    }catch (NoSuchProviderException e){e.printStackTrace();}
    keyGen.initialize(1024);
    key = keyGen.generateKeyPair();
    return key;
}

public PublicKey getpublickey()
{
    return key.getPublic();
}
public PrivateKey getprivatekey()
{
    return key.getPrivate();
}

public byte[] encrypt(byte[] text, PublicKey key) throws Exception
{
    byte[] cipherText = null;
    try
    {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding",PROVIDER);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        cipherText = cipher.doFinal(text);
    }catch (Exception e){throw e;}
    return cipherText;
}

public String encrypt(String text, PublicKey key) throws Exception
{
    String encryptedText;
    try
    {   byte[] cipherText = encrypt(text.getBytes(),key);
        encryptedText = encodeToBASE64(cipherText);
    }catch (Exception e){throw e;}return encryptedText;
}

public byte[] decrypt(byte[] text, PrivateKey key) throws Exception
{
    byte[] dectyptedText = null;
    try
    {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding",PROVIDER);
        cipher.init(Cipher.DECRYPT_MODE,key);
        dectyptedText = cipher.doFinal(text);
    }catch (Exception e){throw e;}
    return dectyptedText;
}

public String decrypt(String text, PrivateKey key) throws Exception
{
    String result;
    try
    {   byte[] dectyptedText = decrypt(decodeToBASE64(text),key);
        result = new String(dectyptedText);
    }catch (Exception e){throw e;}
    return result;
}


public String getKeyAsString(Key key)
{
    byte[] keyBytes = key.getEncoded();
    BASE64Encoder b64 = new BASE64Encoder();
    return b64.encode(keyBytes);
}

public PrivateKey getPrivateKeyFromString(String key) throws Exception
{
    KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM_USED);
    BASE64Decoder b64 = new BASE64Decoder();
    EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(b64.decodeBuffer(key));
    PrivateKey privateKey = keyFactory.generatePrivate(privateKeySpec);
    return privateKey;
}

public PublicKey getPublicKeyFromString(String key) throws Exception
{
    BASE64Decoder b64 = new BASE64Decoder();
    KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM_USED);
    EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(b64.decodeBuffer(key));
    PublicKey publicKey = keyFactory.generatePublic(publicKeySpec);
    return publicKey;
}

private String encodeToBASE64(byte[] bytes)
{
BASE64Encoder b64 = new BASE64Encoder();
return b64.encode(bytes);
}

private byte[] decodeToBASE64(String text) throws IOException
{
    BASE64Decoder b64 = new BASE64Decoder();
    return b64.decodeBuffer(text);
}

public static void main(String[] args) throws Exception {
    RSAUTIL rsa= new RSAUTIL();
    System.out.println(rsa.decrypt(rsa.encrypt("123",
    rsa.getPublicKeyFromString(rsa.getKeyAsString(rsa.getpublickey()))),
    rsa.getPrivateKeyFromString(rsa.getKeyAsString(rsa.getprivatekey()))));
}

}

出力: 123