古特曼算法

古特曼算法（英语：Gutmann method）是一种将电脑硬盘中的内容，如档案，进行安全抹除的算法。该算法由彼得·古特曼与科林·普拉姆设计，主要特色是在要被抹除的区段中重复写入35个片段。

而片段的选择，是在假定使用者不知道使用在硬盘的编码机制为何，因此该算法特别为3种不同型别的硬盘，设计不同的片段。如果使用者知道硬盘所使用的编码模式，就可以为这个硬盘选用专属的片段模式。一个硬盘当中不同的编码机制，会需要不同的片段模式。

在古特曼算法当中，大多数的片段模式多是设计给较老旧的MFM/RLL编码硬盘。较为近代的硬盘类型技术上都不是使用这种较老旧的编码模式，造成这些由古特曼设计的片段模式成为累赘^[1]。因此，从约2001年开始，ATA IDE与SATA硬盘制造商，针对“安全抹除”标准进行支援设计，避免了使用古特曼算法抹除整个硬盘的需求^[2]。

该算法最早出现于1996年6月的期刊文章《Secure Deletion of Data from Magnetic and Solid-State Memory》。

参考文献[编辑]

^ Gutmann, Peter. (July 22–25, 1996)Secure Deletion of Data from Magnetic and Solid-State Memory. （页面存档备份，存于互联网档案馆） University of Auckland Department of Computer Science. Epilogue section. (writing, "In fact performing the full 35-pass overwrite is pointless for any drive since it targets a blend of scenarios involving all types of (normally-used) encoding technology, which covers everything back to 30+-year-old MFM methods (if you don't understand that statement, re-read the paper). If you're using a drive which uses encoding technology X, you only need to perform the passes specific to X, and you never need to perform all 35 passes. For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do. As the paper says, "A good scrubbing with random data will do about as well as can be expected". This was true in 1996, and is still true now.").
^ Communications Security Establishment. July 2006. Clearing and Declassifying Electronic Data Storage Devices （页面存档备份，存于互联网档案馆）, page 7.

[Gutman-1] Gutmann, Peter. (July 22–25, 1996)Secure Deletion of Data from Magnetic and Solid-State Memory. （页面存档备份，存于互联网档案馆） University of Auckland Department of Computer Science. Epilogue section. (writing, "In fact performing the full 35-pass overwrite is pointless for any drive since it targets a blend of scenarios involving all types of (normally-used) encoding technology, which covers everything back to 30+-year-old MFM methods (if you don't understand that statement, re-read the paper). If you're using a drive which uses encoding technology X, you only need to perform the passes specific to X, and you never need to perform all 35 passes. For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do. As the paper says, "A good scrubbing with random data will do about as well as can be expected". This was true in 1996, and is still true now.").

[2] Communications Security Establishment. July 2006. Clearing and Declassifying Electronic Data Storage Devices （页面存档备份，存于互联网档案馆）, page 7.

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