I lend my external drive for friend and what I get back. I get back a lot of mallware on it. And antivirus can’t curry executable files. So I thought maybe is somewhere a program that can encrypt entire hard drive with two passwords one for full access and one for read only. I do not found anything like that but I found a True Crypt program. True Crypt is open source encryption software. It can encrypt entire partition, disk or make a special file called container. That container has inside file system and mounts and acts like file system. In containers is possibility to create hidden container that means with one password you can access one encrypted partition and with other can access hidden partition. This is useful when you are exhorted and have to say password. On first fake container you put useless information and in hidden volume all important data. Hidden container not increase file in which is saved it. It created inside regular container and can’t be bigger than regular container. Regular container partition not shrinks when hidden volume is created and allow write to full of data. That means that when you write data in regular partition is possibility to write on hidden container and that will damage hidden volume. True Crypt has ability to encrypt and operating system. One interesting feature is instead typed password to use file. File can be generated by True Crypt or can be any file in system for example picture or mp3 file.
When volume is created it is mounted as file system. You can access to file like in ordinary file systems. When you read/write to encrypted volume all data encrypted/decrypted without any user interruption. Encryption/decryption not using a lot of memory and processor power, so it not hit in performance. True crypt very reliable even from power failure or bad sectors on disk. True Crypt crypts container by segments, so if start bad sector on disk then in encrypted partition will be lost one segment but not all container.
True Crypt has very good encrypting algorithms. In official site is written that one banker was suspicion about machinations and he has all hard drive encrypted with True Crypt. So FBI tried one year to brute force that hard drive and not succeeded.