One-Time Pad
Calculate One-Time Pad instantly with the exact formula and a worked example.
One-Time Pad
Message lengthbytes
Key lengthbytes
Key entropy
800bits
Required key length
100bytes
Number of possible keys
10^240.8
Security
Perfect (with a truly random one-time key)
More about: One-Time Pad
What it calculates
The “One-Time Pad” calculator computes Key entropy in bits from 2 parameters: message length (bytes), key length (bytes).
Standard IT calculations for developers and sysadmins.
Example calculation
With parameters Message length = 100 bytes, Key length = 100 bytes the result is 800 bits.
How to use
- Enter message length and key length — each field above is adjustable with a slider.
- Key entropy (bits) is calculated automatically as you type.
- Check the worked example below to see the formula applied to real numbers.
- Copy the result or bookmark this calculator.
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FAQ
How is One-Time Pad calculated?
The One-Time Pad calculator computes Key entropy (in bits) from message length, key length. Enter your values above and the exact formula is applied instantly; a worked example with real numbers is shown below.
Is the One-Time Pad calculator free?
Yes. It is completely free, needs no signup, runs entirely in your browser, and sends no data to any server.
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