6.3.3. DES in CBC mode with an MD4 checksum (des-cbc-md4)

The des-cbc-md4 encryption mode encrypts information under the Data Encryption Standard [11] using the cipher block chaining mode [12]. An MD4 checksum (described in [15]) is applied to the confounder and message sequence (msg-seq) and placed in the cksum field. DES blocks are 8 bytes. As a result, the data to be encrypted (the concatenation of confounder, checksum, and message) must be padded to an 8 byte boundary before encryption. The details of the encryption of this data are identical to those for the descbc-md5 encryption mode.