Aparentemente, você não pode definir os parâmetros minlen
como 1
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página de manual do pam_cracklib
minlen=N
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Note that there is a pair of length limits in Cracklib itself, a
"way too short" limit of 4 which is hard coded in and a defined limit (6)
that will be checked without reference to minlen. If you want to allow
passwords as short as 5 characters you should not use this module.