pwpls is a simple password generator.

It allows you to create passwords that conform to specific guidelines.

Some password guidelines require n special characters, x uppercase letters, a minimum length of y, and so on.

pwpls allows you to conform to these guidelines in a dead-simple way.

# Password with a length of 20, 3 special characters, and 5 uppercase
# letters. The shorthand flag notation is the same as
# pwpls --length=20 --special=3 --uppercase=5

eric@archbox ~/ $ pwpls -l 20 -s 3 -u 5

It'll return an error message if you try to do something impossible. For example, asking pwpls for a password with a length of 5 that contains 10 special characters will look like this:

eric@archbox ~/ $ pwpls -l 5 -s 20
pwpls: special + uppercase + digits should be <= length

By default it uses the OS' PRNG to scoop up n bytes, where n is the length of password you want.

It then encodes the random bytes using hexidecimal encoding (to convert the random bytes to printable characters). It then randomly truncates the encoded buffer to the desired length (hexidecimal encodes twice as large as its input) and then randomly loops over the truncated buffer, swapping out characers until the password conforms to the provided specifications.

It randomly loops by using the xorshift 4096 algorithm (seeded with a random 64-bit prime) to generate a random number x and using x % len(buffer) as the position of the character to replace.

The tables of characters used to replace other characters are defined as

var specialTable = table{
	'~', '`', '!', '@',
	'#', '$', '%', '^',
	'&', '*', '(', ')',
	'_', '+', '[', ']',
	'{', '}', '|', '\\',
	'"', '\'', ';', ':',
	'.', '>', ',', '<',
	'/', '?',
}

var upperTable = table{
	'A', 'B', 'C', 'D',
	'E', 'F', 'G', 'H',
	'I', 'J', 'K', 'L',
	'M', 'N', 'O', 'P',
	'Q', 'R', 'S', 'T',
	'U', 'V', 'W', 'X',
	'Y', 'Z',
}

var lowerTable = table{
	'a', 'b', 'c', 'd',
	'e', 'f', 'g', 'h',
	'i', 'j', 'k', 'l',
	'm', 'n', 'o', 'p',
	'q', 'r', 's', 't',
	'u', 'v', 'q', 'x',
	'y', 'z',
}

var digitTable = table{
	'0', '1', '2', '3',
	'4', '5', '6', '7',
	'8', '9',
}

The Unilicense: Public domain.