Follow these steps to run the Diffie-Hellman Key Establishment simulation.

Step 1: Public Information Setup

• Set public parameters in either way:
  • Use Generate Prime to load a preset prime $p$ and default generator $g$.
  • Or type your own values for $p$ and $g$ directly in the input boxes.
• Optional: Click Another Generator to cycle valid preset generators for the currently selected preset prime.
• Public parameters must satisfy $p > 2$ and $1 < g < p$.

Step 2: Private Key Selection

• For Alice:
  • Enter a private key $a$ manually, or click Generate A.
• For Bob:
  • Enter a private key $b$ manually, or click Generate B.
• Each private key must satisfy $0 < a < p$ and $0 < b < p$.

Step 3: Public Key Calculation

• For Alice, click Calculate g^a to compute:
  • $A = g^a \bmod p$
• For Bob, click Calculate g^b to compute:
  • $B = g^b \bmod p$

Step 4: Exchange Public Keys

• Click Send Public Key to Bob to copy Alice's public key into Bob's received field.
• Click Send Public Key to Alice to copy Bob's public key into Alice's received field.

Step 5: Shared Secret Computation

• Alice clicks Calculate Shared Secret to compute:
  • $K_A = B^a \bmod p$
• Bob clicks Calculate Shared Secret to compute:
  • $K_B = A^b \bmod p$

Step 6: Verification

• Check the verification status shown in Step 3.
• Success condition:
  • $K_A = K_B$
• If the values do not match, verify that:
  • Both users used the same $p$ and $g$.
  • Public keys were recalculated after any input change.
  • Public keys were exchanged before shared-secret calculation.

Notes on Simulation Behavior

• The simulation clears stale computed outputs whenever core inputs change.
• Validation messages are shown when inputs are out of range or missing.
• This simulation demonstrates correctness of key establishment, not authentication against active attackers.