Toy HTTPS

Derive Session Keys

Derive tiny application keys from the shared secret and both randoms. This is toy arithmetic only, not deployable security.

Example

Derive tiny application keys from the shared secret and both randoms.

highlighted = computed this step

Step 1 — Inputs

Set up the exact toy cryptography values.

shared, client_random, server_random(2, 4, 9)\begin{array}{c|c}\text{shared, client\_random, server\_random}&\text{(2, 4, 9)}\end{array}

Step 2 — Encryption key

Compute the highlighted cryptography value.

(shared + client_random + server_random) mod 1615\begin{array}{c|c}\text{(shared + client\_random + server\_random) mod 16}&\hlmath{\text{15}}\end{array}

Step 3 — MAC key

Compute the highlighted cryptography value.

(shared * client_random + server_random) mod 161\begin{array}{c|c}\text{(shared * client\_random + server\_random) mod 16}&\hlmath{\text{1}}\end{array}
cryptography This lesson follows a tiny HTTPS-like protocol sequence so every value can be checked by hand.