MD5 is a one-way encryption algorithm, which will lose the original information and cannot be used for encryption and decryption of data transmission, but it has a place in network communication, such as the signature algorithm in WeChat payment.

Regardless of the input data size, the output is always 128 bits of information, which is generally displayed as 16.

What is the probability? The description of the image is "less than the probability of winning 5 million prizes in 5 million consecutive years", which is equivalent to having 1 billion files in a billion computers, so it may be the same. General data tables don't need to consider this problem at all.

MD5 is a one-way algorithm, and the original value cannot be obtained. However, some decryption platforms keep encrypted values of many commonly used values. When the equivalence reaches a certain range, it is equivalent to querying the original value from MD5.

Using the characteristics 2 and 3 of MD5, in the network transmission, the received data is subjected to MD5 operation, and if the MD5 values do not match, the data is considered to be tampered with.

Using the stability and dispersion of MD5, we can get a "balanced" table in the array structure to speed up the data search.

transfer

The MD5 algorithm is just a kind of hash algorithm, and the common ones are MD4, SHA-0, SHA- 1 and SHA-2. SHA-2 algorithm is recommended to be used in scenes with high security requirements.