The MD5 encryption confirmation's security has been since very high, many forums and software user correspondence password after the MD5 encryption preserves, compared with formerly merely the definite orders preservation, after the MD5 encryption's preserved information is safer, the MD5 encryption's information security is after all higher, the MD5 encryption way is also unidirectional does not have any reversion to explain. However you whether to know MD5 is also not the true security, the intruder after having obtained the MD5 encryption string of character still may explain the definite orders password through many kinds of methods. Below invites each IT168 the reader follows the author to discuss the MD5 encryption from the actual combat the security.
First, MD5 encryption synopsis:
MD5 is one kind of irreversible encryption algorithm, the md5 full title is message-digest algorithm 5. In the early 90s by mit laboratory for computer science and rsa data security inc ronald l. rivest develops, after md2, md3 and md4 development. Its function lets the large capacity information before using the digital signature software to sign the personal dense spoon the quilt " the compression " to become one kind of security the form (is transforms a random length byte string a fixed-length great integer).
in 1991, rivest developed in the technology more to draw close the mature md5 algorithm. It increased " the safe - scallop in the md4 foundation " the (safety-belts) concept. Although md5 compared to md4 slightly slow somewhat, but is actually safer. This algorithm very obvious has the little different step by four with the md4 design to be composed. the md5 model application is produces hash (message-digest) to section of information (message), prevents to tamper with. For instance, has many softwares under unix to be the same in downloading time some filename, the file extensions named .md5 document, usually has line of texts in this document, approximate structure for example: md5 (tanajiya.tar.gz) = 0ca175b9c0f726a831d895e269332461
This is the tanajiya.tar.gz document digital signature. md5 treats as the entire document a big text information, through its irreversible string of character transformation algorithm, has had this only md5 hash. If will disseminate in this document process in later, regardless of the document content has had any form change (transmission mistake which line will be unstable including in artificial revision or downloading process causes and so on), so long as you to this document recomputation md5 time will discover that the hash will not be the same, from this may determine that you will obtain are only not a correct document. If has a third party authentication organization again, may also prevent the document author with md5 " denying ", this is the so-called digital signature application. md5 also widely uses in encrypting and in the decipher technology. For instance in the unix system user's password is by md5 (or other similar algorithms) after the encryption saves in the filing system. When the user registers, the system calculates the user input's password the md5 value, then goes to and the preservation again carries on the comparison in filing system's md5 value, then specified input password to be whether correct. Through such step, system, in did not know that the user password situation in with clearly marked price may determine the user registers system's validity. Not only this may avoid the user the password clothing having the system manager jurisdiction user to know, moreover also to a certain extent increased the password the difficulty which explains.
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