Search Ctrl K
Home / Tools
THE FEUTEX TOOLKIT

RSA-OAEP Payload Capacity

Compute the maximum OAEP message length for a modulus and hash size.

Computer Systems workspace● Runs in your browser
01 Your input
02 Your result
View or copy raw result data
FormulamLen≤k−2hLen−2
Sources and model references

Worked example

Inputs

RSA modulus bits
2048 bits
Hash output size
32 bytes
Message length
100 bytes

Expected results

Maximum OAEP plaintext
190 bytes
Capacity minus message
90 bytes
Ciphertext length
256 bytes

Load the example in the workspace to reproduce these results. Display rounding does not change the underlying calculation.

How to use this tool

  1. Enter the labeled inputs in the indicated units.
  2. Calculate and compare every output against the stated model assumptions.

Try this example

{
  "bits": 2048,
  "hash": 32,
  "message": 100
}

Accuracy and scope

Size arithmetic only; no key validation, encryption, hash compatibility or cryptographic-security assessment. Simplified analytical model; not a design recommendation or safety certification.

Is my data uploaded?

This tool runs locally in your browser. Input and output are not sent to a processing server. Copy or download your result before leaving the page.