How long does it take to crack a password of 8 characters?
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So, to break an 8 character password, it will take (1.7*10^-6 * 52^8) seconds / 2, or 1.44 years. Note that on a GPU, this would only take about 5 days. On a supercomputer or botnet, this would take 7.6 minutes. As you can see, simply using lowercase and uppercase characters is not enough.