Android公钥加密

Question

我的Android应用程序实现了RSA加密，但后端无法解密应用程序生成的令牌。这是代码，公钥的开始行和结束行在调用之前都被删除了，会有什么问题吗？

String encryptedToken = Base64.encodeToString(encrypt(publicKey, "4111111111111111"), Base64.NO_WRAP);

public static byte[] encrypt(String publicKey, String data) {
        if (TextUtils.isEmpty(publicKey) || TextUtils.isEmpty(data)) {
            return null;
        }
        try {
            // Decode the modified public key into a byte[]
            byte[] publicKeyByteArray = Base64.decode(publicKey.getBytes("UTF-8"),Base64.NO_WRAP);

            Cipher mCipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(publicKeyByteArray);
            Key key = keyFactory.generatePublic(x509KeySpec);
            mCipher.init(Cipher.ENCRYPT_MODE, key);
            return mCipher.doFinal(data.getBytes("UTF-8"));
        }
        catch (UnsupportedEncodingException e) {
            Log.e("RSAKEY", e.getMessage());
        }
        catch (NoSuchPaddingException e) {
            Log.e("RSAKEY", e.getMessage());
        } catch (NoSuchAlgorithmException e) {
            Log.e("RSAKEY", e.getMessage());
        } catch (InvalidKeyException e) {
            Log.e("RSAKEY", e.getMessage());
        } catch (InvalidKeySpecException e) {
            Log.e("RSAKEY", e.getMessage());
        } catch (IllegalBlockSizeException e) {
            Log.e("RSAKEY", e.getMessage());
        } catch (BadPaddingException e) {
            Log.e("RSAKEY", e.getMessage());
        }
        return null;
    }

后端团队提供了以下可以工作的示例代码，但它是针对桌面Java的。Android库没有base64.getEncoder方法。这和我写的非常相似，但我的就是不起作用。

 // Decode the modified public key into a byte[]
            byte[] publicKeyByteArray = Base64.getDecoder().decode(publicKey.getBytes(StandardCharsets.UTF_8));

            // Create a PublicKey from the byte array
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyByteArray);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PublicKey pubKey = keyFactory.generatePublic(keySpec);

            // Get an instance of the Cipher and perform the encryption
            Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");
            cipher.init(Cipher.ENCRYPT_MODE, pubKey);
            byte[] cipherText = cipher.doFinal(ccNum.getBytes(StandardCharsets.UTF_8));

            // Get the encrypted value as a Base64-encoded String
            String encodeToStr = Base64.getEncoder().encodeToString(cipherText);

            // Print out the encoded, encrypted string
            System.out.println("Encrypted and Encoded String: " + encodeToStr);

我比较了每一步的字节数组值。桌面密码和android密码得到的输入完全相同。然而，来自Android code Cipher.dofinal的结果不能被后端解密。如果我把桌面结果放到REST调用体中，它们工作得很好，所以它不是由REST调用引起的。

Answer 1

最后团队里有人破解了这个。原因是Android操作系统使用Bouncy castle,后端使用Sun作为提供者,导致后端抛出BadPaddingException。要使其工作，密码需要在Android上以这种方式初始化：

 mCipher.init(Cipher.ENCRYPT_MODE, key, new
                    OAEPParameterSpec("SHA-256", "MGF1", MGF1ParameterSpec.SHA1,
                    PSource.PSpecified.DEFAULT));

欲了解更多详细信息，请访问本文:http://bouncy-castle.1462172.n4.nabble.com/problems-with-oaep-sha-256-hash-crypto-td1466852.html