An encryption is the way to protection of information against interception by unauthorized persons, but does not protect against being read or deleted. Unencrypted information stored or transmitted by information systems (networks) can be treated as disclosed information. The encryption is the only known effective way to implement the protection of information transmitted on the network. For this purpose, the encryption information codes are used – i.e. the family of transformations is used to transmit information form incomprehensible or useless to the attacker.
Every process of encryption involves information converting (overt) in another (the so-called. cryptogram or ciphertext) using mathematical function and password encryption (called. wrench). The reverse process (called decryption) lies in the fact that the cryptogram is converted back into the original information is known by means of mathematical function and a key.
MD5 is an algorithm in the field of cryptography. It is popular cryptographic hash function which generates 128-bit shortcut for any length data string. In 2004, the way to generate MD5 collisions was found, which reduced its security in some applications (e.g. signing files). Due to known cryptanalytic attacks MD5 function definitely should not be used in applications that require resistance to collisions (e.g. the digital signature). In others, such as HMAC, it may still provide satisfactory level of safety. Although, the use of MD5 is new solutions is not recommended.
Md5sum is computer program which calculates and verifies MD5 hash functions. It generates any string of 128-bit checksums. The algorithm is described in RFC1321 specification. MD5 hash is commonly used for verification of files integrity. That is, it allows us to verify if the file has not been changed because of file transfer, disk error and so on. Md5sum program is default installed in most Unix, Linux and Unix-like operating systems or compatibility layer. BSD (including Mac OS X) have a similar tool called md5. For System Microsoft Windows there is md5 application.