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Data erasure (also called data clearing or data wiping) is a software-based method of overwriting the data that aims to completely destroy all electronic data residing on a hard disk drive or other digital media. Permanent data erasure goes beyond basic file deletion commands, which only remove direct pointers to the data disk sectors and make the data recovery possible with common software tools. Unlike degaussing and physical destruction, which render the storage media unusable, data erasure removes all information while leaving the disk operable, preserving IT assets and the environment. New flash memory–based media implementations, such as solid-state drives or USB flash drives can cause data erasure techniques to fail allowing remnant data to be recoverable. Software-based overwriting uses a software application to write a stream of zeros, ones, and/or meaningless pseudorandom data onto all of a hard drive's sectors. There are key differentiators between data erasure and other overwriting methods, which can leave data intact and raise the risk of data breach, identity theft and/or failure to achieve regulatory compliance. Many data eradication programs also provide multiple overwrites so that they support recognized government and industry standards, though a single-pass overwrite is widely considered to be sufficient for modern hard drives. Good software should provide verification of data removal, which is necessary for meeting certain standards. To protect the data on lost or stolen media, some data erasure applications remotely destroy the data if the password is incorrectly entered. Data erasure tools can also target specific data on a disk for routine erasure, providing a hacking protection method that is less time-consuming than software encryption. Hardware/firmware encryption built into the drive itself and/or integrated controllers is now a popular solution with no degradation in performance at all. Presently, dedicated hardware/firmware encryption solutions can perform a 256-bit full AES encryption faster than the drive electronics can write the data. Drives with this capability are known as self-encrypting drives (SEDs); they are present on most modern enterprise-level laptops and are increasingly used in the enterprise to protect the data. Changing the encryption key renders inaccessible all data stored on a SED, which is an easy and very fast method for achieving a 100% data erasure. Theft of an SED results in a physical asset loss, but the stored data are inaccessible without the decryption key which is not stored on a SED, assuming there are no effective attacks against AES or its implementation in the drive hardware, now or in the future. ==Importance== Information technology (IT) assets commonly hold large volumes of confidential data. Social security numbers, credit card numbers, bank details, medical history and classified information are often stored on computer hard drives or servers. These can inadvertently or intentionally make their way onto other media such as printer, USB, flash, Zip, Jaz, and REV drives. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Data erasure」の詳細全文を読む スポンサード リンク
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