Last week, SalvationDATA received a Hitachi HDD from one of our clients for password remove. It belongs to Hitachi 7K200 series with HTS722020K9SA00 FDE as the Model. As no tool over the world supports that series, the client sent it to us for help. After several days’ hard working, engineers from SalvationDATA remove the password and add the support for 7K200 series in version 3.3 of HD Doctor for Hitachi. However, engineers find the data is meaningless despite ATA password is removed, which means the data on that drive is encrypted. Why the data is still encrypted after password remove? Full Disk Encryption or Bulk Data Encryption (Hitachi engineers call it this way) tells you the answer.
FDE (Full Disk Encryption) is a new technology introduced to HDD encryption. Seagate is the first to add FDE function to its HDD ；Fujitsu， Samsung and Hitachi follow the steps. Hitachi releases 5K500 B., 7K200 series etc, which support FDE function.
In FDE HDD, there is an Encryption/Decryption chip, which in charge of encryption/decryption written to/read from the HDD. Data written to disk should first be encrypted and then be written to disk; data read from disk should be first decrypted and then be read to OS.
As you know, data stored on HDD is binary code. Therefore, data written to disk should first be converted to binary digit. For example, suppose we need to write number “8″ to disk. First, “8″ should be converted to binary digit “1000″. Then an ECC will be calculated accordingly. Last, the binary digit “1000″ together with ECC code will be written to disk. While for data read, the computer first read “1000″ together with ECC code out, then remove ECC with “1000″ remained. Last, convert it to number “8″.
Let’s examine data stored on an FDE HDD (still we take the example above). Suppose the keys is x, data is y and Encrypted data is F, then the format is F=x*y. In the last example, suppose x=9, then we get F=8*9=72. Convert “72″ to be binary code “01110010″. Then “01110010″ together with calculated ECC is written to disk. While for data read, “01110010″ together with ECC code is read out and then “01110010″ is converted to “72″. In the last, “72″ is decrypted to “8″.
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