Decrypting assertion fails

[Cantor, Scott]

> 4. While decrypting at SP, we are using the private key for the public key in SP
> metadata(code below)

I'm not doing to debug your code, but based on the error I would expect that you're trying to decrypt the data with a private key and not using the private key as a key decryption key first.

> My Cryptography knowledge is limited, so pardon me if I'm wrong. WikiPedia
> says AES is symmetric key algorithm. If IdP uses public key for encryption,
> why does org.opensaml.xml.encryption.Decrypter try to decrypt using AES
> and fails?

You need to read the XML Encryption specification. Data encryption is never done with assymetric algorithms. They wrap generated symmetric keys used for the data.

-- Scott