Detailed explanation of pseudo-random number generator CSPRNG in PHP7

CSPRNG is a pseudo-random number generator. As a tool, commonly used algorithms include MD5 or SHA1, etc.

In PHP7, the following two CSPRNG functions are introduced to generate cryptographically secure integers and strings in a cross-platform way.

• random_bytes() - Generate cryptographically secure pseudo-random bytes.

• random_int() - Generate cryptographically secure pseudo-random integers.

1.random_bytes()

Random_bytes() is suitable for generating passwords, cryptographically random strings of any length, such as : Generate salt, key or initial vector.

Syntax:

string random_bytes ( int $length )

• Parameters: length - Returns the byte length of the random string

• Return value: Returns encryption A string with the requested number of safe random bytes.

Example:

<?php
$bytes = random_bytes(5);
print(bin2hex($bytes));//随机生成
?>

2.random_int()

It is very important that random_int() produces results suitable for use encrypted random integer.

Syntax:

int random_int ( int $min , int $max )

• min - Returns the minimum value, it must be PHP_INT_MIN or a greater value

• max - Returns the maximum value , it must be less than or equal to PHP_INT_MAX
  

Example:

<?php
print(random_int(100, 999));//随机生成100-999的数
echo "<br/>";
print(random_int(-1000, 0));//随机生成-100至0的数
?>

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