Why would you use symmetric encryption instead of asymmetric one?

Are there any computer hard drives with built-in encryption?

• I'm aware of many drives which claim to offer encryption, but I am referring to verifiable strong encryption, not just password protection. Probably requires a master key, encrypted with a user supplied password, used to encrypt all the data written to the drive. I've been utterly perplexed by some drive manufacturers, one confirmed to me that although their drive supported encryption, there was no way to actually set a password. I didn't manage to find out what use this was.

• Answer:

  Yes, any drive advertised as FDE (full disk encryption) or SED (self-encrypting drive) or as supporting TCG Opal or TCG Enterprise should have built-in hardware encryption. They work the way you describe: master key wrapped by user password, all data written to the drive is automatically encrypted, all data read from the drive is automatically decrypted. The master key is not accessible by the manufacturer, but I'm not sure how to prove that. What would it take to prove that to you? As for the drives that support encryption but have no way to set a password, there can be many reasons behind that. One common reason is that the encryption is there so the user can perform a cryptographic erase (just change the master key and all your data is instantly and securely erased). If this is the purpose of the encryption, then there is no need for a password.