Tech & Web
Secure Password Generator
Generate strong, cryptographically secure passwords with custom entropy rules.
Inputs
Results
Generated Password
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Strength Level
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Entropy Estimate
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How It Works
The password generator compiles random passwords by fetching cryptographically secure random integers using JavaScript's native browser `crypto.getRandomValues()` API (which routes directly to the OS kernel entropy sources rather than predictable seeds). It isolates selected pools, filters ambiguous matches, and computes binary Shannon entropy: $H = L \log_2(N)$ bits.
Formula Used
Entropy (Bits) = L × log2(N)
Shannon entropy measures password strength in bits of security. L is the password length, and N is the size of the character pool selected. Each character chosen adds log2(N) bits of entropy.
Worked Example
Here is a step-by-step example of how these values are calculated:
Length
16
Allowed Char Pools
Upper, Lower, Number, Symbol
Result: Generates a highly secure cryptographically random string (e.g. `g*P2q7$Z#L9mK5@v`). Entropy: ~105 bits (Very Strong).
Frequently Asked Questions
What makes this password generator secure?
Unlike mathematical `Math.random()`, which uses predictable algorithmic formulas, this tool calls Web Crypto APIs. This returns cryptographically secure numbers with high entropy, making the passwords practically immune to pattern guessing.
What is Shannon entropy?
Entropy measures a password's resistance to brute-force crack attempts. A rating above 60 bits is generally considered strong for average accounts, while 80+ bits is recommended for critical infrastructure.