Lesson plan

Md5sum

is a computer program that calculates and verifies 128-bit MD5 hashes, as described in RFC 1321. The MD5 hash functions as a compact digital fingerprint of a file. As with all such hashing algorithms, there is theoretically an unlimited number of files that will have any given MD5 hash. However, it is very unlikely that any two non-identical files in the real world will have the same MD5 hash, unless they have been specifically created to do so. The underlying MD5 algorithm is no longer deemed secure. Thus, while is well-suited for identifying known files in situations that are not security related, it should not be relied on if there is a chance that files have been purposely and maliciously tampered. In the latter case, the use of a newer hashing tool such as sha256sum is recommended. is used to verify the integrity of files, as virtually any change to a file will cause its MD5 hash to change. Most commonly, is used to verify that a file has not changed as a result of a faulty file transfer, a disk error or non-malicious meddling. The program is included in most Unix-like operating systems or compatibility layers such as Cygwin. The original C code was written by Ulrich Drepper and extracted from a 2001 release of .

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Article summary

is a computer program that calculates and verifies 128-bit MD5 hashes, as described in RFC 1321. The MD5 hash functions as a compact digital fingerprint of a file. As with all such hashing algorithms, there is theoretically an unlimited number of files that will have any given MD5 hash. However, it is very unlikely that any two non-identical files in the real world will have the same MD5 hash, unless they have been specifically created to do so. The underlying MD5 algorithm is no longer deemed secure. Thus, while is well-suited for identifying known files in situations that are not security related, it should not be relied on if there is a chance that files have been purposely and maliciously tampered. In the latter case, the use of a newer hashing tool such as sha256sum is recommended. is used to verify the integrity of files, as virtually any change to a file will cause its MD5 hash to change. Most commonly, is used to verify that a file has not changed as a result of a faulty file transfer, a disk error or non-malicious meddling. The program is included in most Unix-like operating systems or compatibility layers such as Cygwin. The original C code was written by Ulrich Drepper and extracted from a 2001 release of .

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Discussion questions

  1. Summarise the article in your own words. Which single claim would you verify first, and why?
  2. Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
  3. If two sources disagreed about one of these facts, what would you need in order to trust one over the other?

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Key claims and bibliography are generated from the same tracked claims and sources as the article page.