PHP - 无论如何在PHP中加密/解密哈希？ [关闭]

Question

I'm interested to encrypt/decrpyt hash in PHP.

But as I know hash can be encoding only with md5, sha1, sha256.

However, is it possible to make encrypt/decrpyt in PHP by another hash like ripemd160, haval256,5 or ripemd256?

Thank

Answer 1

Hashing algorithms are not encryption algorithms. Hashing algorithms have the following principles:

• Specific input produces always the same output
• The input cannot be resolved based on the output
• Any change to input will produce different output

Technically the last one is not true, because you have limited amount of possible outputs but basically unlimited amount of possible inputs. Therefore there will be other inputs that produces the same output, but for strong hashing algorithms finding those collisions takes VERY long time as @delboy1978uk explained.

MD5 is an example of a weak hashing algorithm that you should not use for secure hashes. Collision attacks against MD5 are cheap. On the other hand hashing algorithms in SHA2 family can be considered secure (take SHA256 for example).

Encryption algorithms require a key or multiple keys to allow you to do decryption on the cipher text.

The short answer to your questions is no.