How to decrypt with RSA-OAEP/AES?

[ralph-xmlsecurity]

Hi,

I'm having difficulty decrypting an RSA/AES-encrypted document. I used 
RSA-OAEP in wrap mode to encrypt a shared key:

xmlCipherRSA.init(XMLCipher.WRAP_MODE, pk);
xmlCipherAES.init(XMLCipher.ENCRYPT_MODE, symKey);
encKey = xmlCipherRSA.encryptKey(document, symKey);

and encrypted OK.

Then I wanted to decrypt:

 xmlCipherRSA.init(XMLCipher.UNWRAP_MODE, privateKey);

 Element encryptedDataElement = (Element) document
        .getElementsByTagNameNS(EncryptionConstants.EncryptionSpecNS,
        EncryptionConstants._TAG_ENCRYPTEDDATA).item(0);

Element encryptedKeyElement = (Element) encryptedDataElement
        .getElementsByTagNameNS(EncryptionConstants.EncryptionSpecNS,
        EncryptionConstants._TAG_ENCRYPTEDKEY).item(0);

EncryptedKey encryptedKey = 
xmlCipherRSA.loadEncryptedKey(encryptedKeyElement);

// xmlCipherRSA.setKEK(privateKey);
Key secretKey = xmlCipherRSA.decryptKey(encryptedKey);

At which point I get:

Exception in thread "main" java.lang.NullPointerException
        at org.apache.xml.security.encryption.XMLCipher.decryptKey(Unknown 
Source)
        at 
tue.cryptography.messages.PDPCryptoOperator.decryptMsg(PDPCryptoOperator.java:190)
        at tue.cryptography.messages.FactoryTester.main(FactoryTester.java:64)

I guess I do something in the wrong order or have omitted a step - but which?

Thanks,
Ralph

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