История изменений

Если мне память с возрастом совсем не отшибло, то я читал статью, где говорилось, что после забития нулями можно прочитать старые значения в некоторых случаях и при некоторых условиях.

The origin lies in work by Peter Gutmann, who showed that there is some memory in a disk bit: a zero that’s been overwritten with a zero can be distinguished from a one that’s been overwritten with a zero, with a probability higher than 1/2. However, Gutmann’s work has been somewhat overhyped, and does not extend to modern disks. “The urban legend of multipass hard disk overwrite and DoD 5220-22-M” by Brian Smithson has a good overview of the topic.

The article that started it is “Secure Deletion of Data from Magnetic and Solid-State Memory” by Peter Gutmann, presented at USENIX in 1996. He measured data remanence after repeated wipes, and saw that after 31 passes, he was unable (with expensive equipment) to distinguish a multiply-overwritten one from a multiply-overwritten zero. Hence he proposed a 35-pass wipe as an overkill measure.

Note that this attack assumes an attacker with physical access to the disk and somewhat expensive equipment. It is rather unrealistic to assume that an attacker with such means will choose this method of attack rather than, say, lead pipe cryptography.

Если мне память с возрастом совсем не отшибло, то я читал статью, где говорилось, что после забития нулями можно прочитать старые значения в некоторых случаях и при некоторых условиях.

The origin lies in work by Peter Gutmann, who showed that there is some memory in a disk bit: a zero that’s been overwritten with a zero can be distinguished from a one that’s been overwritten with a zero, with a probability higher than 1/2. However, Gutmann’s work has been somewhat overhyped, and does not extend to modern disks. “The urban legend of multipass hard disk overwrite and DoD 5220-22-M” by Brian Smithson has a good overview of the topic. The article that started it is “Secure Deletion of Data from Magnetic and Solid-State Memory” by Peter Gutmann, presented at USENIX in 1996. He measured data remanence after repeated wipes, and saw that after 31 passes, he was unable (with expensive equipment) to distinguish a multiply-overwritten one from a multiply-overwritten zero. Hence he proposed a 35-pass wipe as an overkill measure. Note that this attack assumes an attacker with physical access to the disk and somewhat expensive equipment. It is rather unrealistic to assume that an attacker with such means will choose this method of attack rather than, say, lead pipe cryptography.