Located somewhere within the body - typically in or near the brain - an internal secure datadrive is exactly what it says on the box.
Known colloquially as a greybox, braincan, crashfile, or any number of other pseudonyms, the internal secure datadrive is useful for virtually everyone. Backing up significant moments in one's life is one common use, as is backing up seemingly-sensitive corporate information for resale to competing interests.
Each internal secure datadrive has its own security key - if for private use, this key is known only to the bearer. If for corporate use, typically the drive's bearer has no knowledge of the security key. While the nature of the security key does not render the drive hackproof, it does make it troublesome to hack.
Each rank invested in a datadrive reduces hack attempts used upon it by 10%, up to rank 5.