Secure XML: The New Syntax for Signatures and Encryption

18.8. Symmetric Key Wrap Algorithms

Symmetric key wrap algorithms are shared secret key encryption algorithms designed for encrypting and decrypting symmetric keys and providing an integrity check. They take, as implicit parameters, their keying material and the key to encrypt or decrypt. Their identifiers appear as Algorithm attributes to EncryptionMethod elements that are children of EncryptedKey, which is in turn a child of KeyInfo (see Figure 18-1). The type of key being wrapped is indicated by the Algorithm attribute of the EncryptionMethod child of the parent of the KeyInfo grandparent of the EncryptionMethod specifying the symmetric key wrap algorithm (see Figure 18-2).

18.8.1. CMS Key Checksum

Some key wrap algorithms use the Key Checksum ...