Digitos only (0-9):
4 chars: instant · 6 chars: 1 second · 8 chars: 1 minute · 10 chars: 2 horas

Minusculas + digitos (a-z, 0-9):
4 chars: instant · 6 chars: 30 segundos · 8 chars: 8 horas · 10 chars: 1 year

Upper + lower + digitos + special chars:
4 chars: instant · 8 chars: 8 horas · 12 chars: 34,000 anos · 16 chars: 1 billion anos