With NIST finally updating their standards to recommend 15 character password minimums last, I like to use their recommendations and compare them to these charts show how effective such a password would be.
Using E = L x log2(R), where E is entropy, L is number of characters in the password (15), and R is the total number of possible characters used (26 for all lowercase letters), you can get ~70 bits of entropy. Using a password manager like Bitwarden for a 15 character password using the full character set minus the ambiguous characters (65 characters total) leads to ~90 bits of entropy.
Using these charts and figures from the article, a well configured bcrypt setup means even the fastest computer systems still in 2025 cap out at 1 billion hashes per second for offline cracking (without getting into Nation States spending billions on just cracking your passwords, or dedicating all the world’s supercomputers or some other speculations). So to calculate how long it would take with a “realistic” password cracker in 2025, would use this formula:
((((((2^(70-1))/ 1 billion hashes per second)/ 60 seconds)/ 60 minutes)/ 24 hours)/ 365 days) to get ~18,700 years. (Nearly 20 billion years for the Bitwarden generated one)
But without a password filter checking for known bad passwords somewhere like Have I Been Pwned, even a 30 character password that has been leaked is useless. Would be instantly “cracked”. So I personally would have the password policy be:
1. 15 character minimum, no composition rules.
2. All passwords filtered for known bad passwords against HIBP.
3. Accounts protected by MFA.
4. Combination of network controls, best practices security configurations, and alerts and monitoring to help detect and limit/eliminate password guessing attacks, password database dumps.
kemotep•1y ago
Using E = L x log2(R), where E is entropy, L is number of characters in the password (15), and R is the total number of possible characters used (26 for all lowercase letters), you can get ~70 bits of entropy. Using a password manager like Bitwarden for a 15 character password using the full character set minus the ambiguous characters (65 characters total) leads to ~90 bits of entropy.
Using these charts and figures from the article, a well configured bcrypt setup means even the fastest computer systems still in 2025 cap out at 1 billion hashes per second for offline cracking (without getting into Nation States spending billions on just cracking your passwords, or dedicating all the world’s supercomputers or some other speculations). So to calculate how long it would take with a “realistic” password cracker in 2025, would use this formula:
((((((2^(70-1))/ 1 billion hashes per second)/ 60 seconds)/ 60 minutes)/ 24 hours)/ 365 days) to get ~18,700 years. (Nearly 20 billion years for the Bitwarden generated one)
But without a password filter checking for known bad passwords somewhere like Have I Been Pwned, even a 30 character password that has been leaked is useless. Would be instantly “cracked”. So I personally would have the password policy be:
1. 15 character minimum, no composition rules.
2. All passwords filtered for known bad passwords against HIBP.
3. Accounts protected by MFA.
4. Combination of network controls, best practices security configurations, and alerts and monitoring to help detect and limit/eliminate password guessing attacks, password database dumps.