First, where is MD5 sacred?
So-called MD5, namely " Message-Digest Algorithm 5 (information - abstract algorithm) “, it one kind of unidirectional function algorithm which by MD2, MD3, the MD4 development comes (is also the HASH algorithm), it was international famous public key encryption algorithm standard RSA first designer R.Rivest inaugurates in the 1990s sends. The MD5 most major function lies, different form large capacity document information before using the digital signature software to sign the personal key " the compression " to become one kind of security the form, place of the key lies in - - this kind " the compression " is irreversible.
In order to let the reader friend have a direct-viewing understanding to the MD5 application, the author comes by an analogy and an example to describe its work process briefly:
Everybody knew, on the Earth anybody has the unique fingerprint, this becomes the Public security organ to distinguish the method which frequently the criminal status most is worth trusting; Is similar with it, MD5 may for any document (, no matter its size, form, quantity) produce one similarly uniquely " the digital fingerprint ", if anybody has made any modification to the document, its MD5 value is also the correspondence " the digital fingerprint " can change.
We in certain softwares download the stand in some software information to see frequently its MD5 value, its function lies in us to be possible after downloading this software, to the document which downloads with the special software (for example Windows MD5 Check and so on) makes a MD5 verification, guaranteed we obtain document the document which provides with this stand is the identical document. Carries on the document verification using the MD5 algorithm the plan to apply massively software aspects and so on downloading station, forum database, system file security. Above the author mentioned the example is only a MD5 basic application, in fact MD5 also uses in encrypting in the decipher technology, like Unix, each kind of BSD system registers the password (before MD5 is born uses is DES encryption algorithm, because latter the MD5 security is higher, DES (immediate correspondence software MyIM which by elimination), the correspondence information encryption for example everybody is familiar with), digital signature and so on many aspects.
Second, the MD5 road of withering away
In fact, from MD5 date of birth, had discovered from American named Van Oorschot and the Wiener two cryptology expert a violence search conflict's function, and budgeted " uses one to use for to search the MD5 conflict specially the machine to be possible average every 24 days to find a conflict ". However because this plan has proven the MD5 unreliability theoretically merely, and realizes the price and the exaggeration (at that time must make this kind of special computer, cost need 1,000,000 US dollars), therefore MD5 is born for more than ten for years from it not to have the new edition or by the other algorithm thorough substitution.
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