用于加密的哈希函数
用于加密的哈希函数(Cryptographic Hashing Function)具有什么样的特点呢？
A cryptographic hash function is a hash function; that is, an algorithm that takes an arbitrary block of dataand returns a fixed-size bit string, the (cryptographic) hash value, such that an (accidental or intentional) change to the data will (with very high probability) change the hash value. The data to be encoded are often called the "message," and the hash value is sometimes called the message digest or simply digest.
The ideal cryptographic hash function has four main or significant properties:
- it is easy to compute the hash value for any given message
- it is infeasible to generate a message that has a given hash
- it is infeasible to modify a message without changing the hash
- it is infeasible to find two different messages with the same hash
Cryptographic hash functions have many information security applications, notably in digital signatures,message authentication codes (MACs), and other forms of authentication. They can also be used as ordinaryhash functions, to index data in hash tables, for fingerprinting, to detect duplicate data or uniquely identify files, and as checksums to detect accidental data corruption. Indeed, in information security contexts, cryptographic hash values are sometimes called (digital) fingerprints, checksums, or just hash values,even though all these terms stand for functions with rather different properties and purposes.
哈希函数的广泛用途：
- 加密（Encryption）
- 索引（Indexing）
- 校验（Checksum）
- 压缩（Compression）