MD5 is the abbreviation for Message-Digest Algorithm 5, which is a widely used cryptographic hash function. It generates hashes with a length of 128 bits. The 128-bit long MD5 hashes are usually written as 32-digit hexadecimal numbers, just like the results of the MD5 generator on this website. MD5 was developed by Ronald L. Rivest in 1991 as a secure replacement for the predecessor MD4. Meanwhile, MD5 is no longer considered to be secure, as different messages with the same MD5 hash value can be generated with justifiable effort.
MD5 hashes were often used to store passwords in databases. This prevents passwords from being stored in plain text, which would otherwise pose a high security risk. As soon as a user needs to be authenticated, the entered password is hashed by MD5 and the hash is compared with the MD5 hash in the database. If both hashes are the same, the user is considered as authenticated. It is important to use so-called salts in order to have an effective protection against rainbow tables.
Another popular application of MD5 is the calculation of checksums to verify downloads. On download pages, a pre-computed MD5 hash value is often available for a downloadable file. Once a file has been downloaded completely, the MD5 hash value of the file content can be calculated using a MD5 generator and then compared with the provided hash value on the download page / file server. If both MD5 checksums are equal, the integrity of the downloaded file is confirmed. Consequently, no errors occurred during the download.
|The MD5 message-digest algorithm is a widely used cryptographic hash function producing a 128-bit hash value.