5.1.1 RC4 Cipher Usage
Implementations of this protocol protect the LSAPR_TRUSTED_DOMAIN_AUTH_BLOB structure by encrypting the data referenced by that structure's AuthBlob field. The RC4 algorithm is used to encrypt the data on request (and reply) and decrypt the data on receipt. The key, required during runtime by the RC4 algorithm, is the 16-byte key specified by the method that uses this structure (for example, see section 18.104.22.168.10). The size of data (the AuthSize field of LSAPR_TRUSTED_DOMAIN_AUTH_BLOB) must remain unencrypted.