RSA Small

Compute Totient

Compute phi for a two-prime RSA modulus. This is toy arithmetic only, not deployable security.

cryptography The values in this lesson are deliberately tiny so every modular arithmetic step can be checked exactly.

Example

Compute phi for a two-prime RSA modulus.

highlighted = computed this step

Step 1 — Set up

Set up the exact toy cryptography values.

p, q(5, 11)\begin{array}{c|c}\text{p, q}&\text{(5, 11)}\end{array}

Step 2 — Factors

Compute the highlighted cryptography value.

p-1, q-1(4, 10)\begin{array}{c|c}\text{p-1, q-1}&\hlmath{\text{(4, 10)}}\end{array}

Step 3 — Totient

Compute the highlighted cryptography value.

phi40\begin{array}{c|c}\text{phi}&\hlmath{\text{40}}\end{array}