java - 如何手动解密 EncryptedAssertion

Question

我想解密 EncryptedAssertion。我尝试使用 OpenSaml Decrypter，但它对我不起作用。我无法解密 EncryptedData我已经问过这个问题 - EncryptedAssertion Decryption failing

当我等待任何解决方案时，我正在尝试手动解密它。它是一种混合加密

我尝试了下面的代码

CipherValue cv = encryptedAssertion.getEncryptedData().getKeyInfo().getEncryptedKeys().get(0).getCipherData().getCipherValue();
String cvalue = cv.getValue();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, getPrivateKey());
String decryptedValue = new String(cipher.doFinal(DatatypeConverter.parseBase64Binary(cvalue)));

我不确定我是否走在正确的道路上，但上面的解密值是我的加密数据的解密 key 。此解密值不是可读格式。不知道下一步该做什么。

获取PrivateKey方法

   public PrivateKey getPrivateKey(){
    Key key = null;
    PrivateKey privateKey = null;
    try {
        KeyStore ks = KeyStore.getInstance("pkcs12", "SunJSSE");         
        ks.load(new FileInputStream("prvkey.pfx"),"".toCharArray());
         Enumeration<String> aliases = ks.aliases();
         while(aliases.hasMoreElements()){
             String alias = aliases.nextElement();
             key  = ks.getKey(alias, "".toCharArray());
             privateKey = (PrivateKey)key; 
        }

} catch (Exception e) {
    e.printStackTrace();
} 
}

基于我编码如下的建议。不确定我是否做对了，我也遇到了错误

 `CipherValue cv = encryptedAssertion.getEncryptedData().getKeyInfo().getEncryptedKeys().get(0).getCipherData().getCipherValue(); 
String cvalue = cv.getValue();
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.UNWRAP_MODE, getPrivateKey());
Key decryptionKey = cipher.unwrap(DatatypeConverter.parseBase64Binary(cvalue), "RSA/ECB/PKCS1Padding", Cipher.SECRET_KEY);

CipherValue cdata = encryptedAssertion.getEncryptedData().getCipherData().getCipherValue();
String cdataValue = cdata.getValue();

byte[] iv = new byte[256 / 16];
IvParameterSpec ivParamSpec = new IvParameterSpec(iv);              
Cipher cipher2 = Cipher.getInstance("AES/CBC/PKCS5PADDING");
SecretKeySpec spec = new SecretKeySpec(decryptionKey.getEncoded(), "AES"); 
cipher2.init(Cipher.DECRYPT_MODE, spec, ivParamSpec );
String decryptedValue = new String(cipher2.doFinal(DatatypeConverter.parseBase64Binary(cdataValue)));`

错误 -

Exception in thread "main" javax.crypto.BadPaddingException: Given final block not properly padded
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:966)
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:824)
at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:436)
at javax.crypto.Cipher.doFinal(Cipher.java:2121)

更新::希望我根据评论做得正确。

byte[] iv = new byte[256/16];
iv = Arrays.copyOfRange(DatatypeConverter.parseBase64Binary(cdataValue), 0,  16);
byte[] cipherBlock = Arrays.copyOfRange(DatatypeConverter.parseBase64Binary(cdataValue), 16,  DatatypeConverter.parseBase64Binary(cdataValue).length);

IvParameterSpec ivParamSpec = new IvParameterSpec(iv);              
Cipher cipher2 = Cipher.getInstance("AES/CBC/PKCS5PADDING");
SecretKeySpec spec = new SecretKeySpec(decryptionKey.getEncoded(), "AES");
cipher2.init(Cipher.DECRYPT_MODE, spec, ivParamSpec );
String decryptedValue = new String(cipher2.doFinal(cipherBlock)); // Same error - Given final block not properly padded

Answer 1

我不会为您提供完整的答案，但我希望能让您走上正确的道路

您不应该只是简单地使用私钥解密计算。

首先使用 RSA/ECB/PKCS1Padding(根据提供的 saml 片段)解密 KeyInfo 值(解开 aes key )

它应该为您提供一个 256 位(32 字节)随 secret 钥，用于加密数据本身

然后使用 AES key 解密数据。请注意，第一个字节(128 位/16 字节，aes block 大小)用作 IV。

进一步阅读

• https://www.w3.org/TR/2002/REC-xmlenc-core-20021210/Overview.html#sec-Processing-Encryption
• https://gusto77.wordpress.com/2017/10/30/encryption-reference-project/