Bulk Data Encryption
A bulk encryption key is generated by hashing one of the MAC keys using CryptHashSessionKey together with the message contents and other data. The message is encrypted/decrypted with one of the bulk encryption keys in the usual manner.
When using a block cipher, the Schannel protocol engine does all necessary block cipher padding. When CryptEncrypt and CryptDecrypt are called, the Final flag is always FALSE and the data length is a multiple of whole block lengths.