Editing MD5 (section)

==Applications==
MD5 digests have been widely used in the [[software]] world to provide some assurance that a transferred file has arrived intact. For example, file servers often provide a pre-computed MD5 (known as [[md5sum]]) [[checksum]] for the files, so that a user can compare the checksum of the downloaded file to it. Most unix-based operating systems include MD5 sum utilities in their distribution packages; Windows users may use the included [[PowerShell]] function "Get-FileHash", the included command line function "certutil -hashfile <filename> md5",<ref>{{cite web |title=Finding Checksum Values in Windows 10 |url=https://answers.microsoft.com/en-us/windows/forum/all/finding-checksum-values-in-windows-10/dbc3c569-4b5a-4967-8810-c25255cdc1fd |publisher=Microsoft Community |access-date=23 November 2023 |archive-date=11 January 2024 |archive-url=https://web.archive.org/web/20240111185213/https://answers.microsoft.com/en-us/windows/forum/all/finding-checksum-values-in-windows-10/dbc3c569-4b5a-4967-8810-c25255cdc1fd |url-status=live }}</ref><ref>{{cite web |title=certutil |url=https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/certutil |website=certutil |publisher=Microsoft Learn |access-date=23 November 2023 |archive-date=23 November 2023 |archive-url=https://web.archive.org/web/20231123190431/https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/certutil |url-status=live }}</ref> install a Microsoft utility,<ref>{{cite web |url=https://support.microsoft.com/kb/841290/en-us |title=Availability and description of the File Checksum Integrity Verifier utility |publisher=Microsoft Support |date=17 June 2013 |access-date=10 April 2014 |archive-date=15 February 2015 |archive-url=https://web.archive.org/web/20150215153720/http://support.microsoft.com/kb/841290/en-us |url-status=live }}</ref><ref>{{cite web |url=https://support.microsoft.com/kb/889768/en-us |title=How to compute the MD5 or SHA-1 cryptographic hash values for a file |publisher=Microsoft Support |date=23 January 2007 |access-date=10 April 2014 |archive-date=9 March 2015 |archive-url=https://web.archive.org/web/20150309230754/http://support.microsoft.com/kb/889768/en-us |url-status=live }}</ref> or use third-party applications. Android ROMs also use this type of checksum.

[[File:CPT-Hashing-File-Transmission.svg|350px|center|Diagram showing use of MD5 hashing in file transmission]]

As it is easy to generate MD5 collisions, it is possible for the person who created the file to create a second file with the same checksum, so this technique cannot protect against some forms of malicious tampering. In some cases, the checksum cannot be trusted (for example, if it was obtained over the same channel as the downloaded file), in which case MD5 can only provide error-checking functionality: it will recognize a corrupt or incomplete download, which becomes more likely when downloading larger files.

Historically, MD5 has been used to store a one-way hash of a [[Password#Form of stored passwords|password]], often with [[key stretching]].<ref>{{Cite web|url = https://www.freebsd.org/cgi/man.cgi?crypt(3)|title = FreeBSD Handbook, Security – DES, Blowfish, MD5, and Crypt|access-date = 2014-10-19|archive-date = 18 February 2017|archive-url = https://web.archive.org/web/20170218081024/https://www.freebsd.org/cgi/man.cgi?crypt(3)|url-status = live}}</ref><ref>{{cite web |url=http://docs.oracle.com/cd/E26505_01/html/816-5174/policy.conf-4.html |title=Synopsis – man pages section 4: File Formats |publisher=Docs.oracle.com |date=1 January 2013 |access-date=10 April 2014 |archive-date=4 March 2016 |archive-url=https://web.archive.org/web/20160304204917/http://docs.oracle.com/cd/E26505_01/html/816-5174/policy.conf-4.html |url-status=live }}</ref> NIST does not include MD5 in their list of recommended hashes for password storage.<ref>[http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf NIST SP 800-132] {{Webarchive|url=https://web.archive.org/web/20161201044854/http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf |date=1 December 2016 }} Section 5.1</ref>

MD5 is also used in the field of [[electronic discovery]], to provide a unique identifier for each document that is exchanged during the legal discovery process. This method can be used to replace the [[Bates numbering|Bates stamp]] numbering system that has been used for decades during the exchange of paper documents. As above, this usage should be discouraged due to the ease of collision attacks.