%%{init: {'themeVariables': {'fontFamily': 'Bernard MT Condensed', 'fontSize': '24px','fontWeight': 'bold'}}}%%
sequenceDiagram
participant Alice as 👩 Alice
participant Bob as 👨 Bob
participant Server as 💻 Server
rect rgb(200, 220, 255)
note over Alice: Step 1
Alice ->> Alice: 👩 generates private key a 🔐
Bob ->> Bob: 👨 generates private key b 🔐
end
rect rgb(200, 220, 255)
note over Alice: Step 2
Alice ->> Alice: 👩 computes public key A = g^a mod p 🔑
Alice ->> Bob: 👩 sends public key A to 👨 ✉️
end
rect rgb(200, 220, 255)
note over Bob: Step 3
Bob ->> Bob: 👨 computes public key B = g^b mod p 🔑
Bob ->> Alice: 👨 sends public key B to 👩 ✉️
end
rect rgb(200, 220, 255)
note over Alice, Bob: Step 4
Alice ->> Alice: 👩 computes shared secret s = B^a mod p = g^(ab) mod p 🔐
Bob ->> Bob: 👨 computes shared secret s = A^b mod p = g^(ab) mod p 🔐
end
rect rgb(200, 220, 255)
note over Alice, Server: Step 5
Alice ->> Server: 👩 sends encrypted message to Server 💻: {Alice, Bob, s} ✉️
Bob ->> Server: 👨 sends encrypted message to Server 💻: {Alice, Bob, s} ✉️
end
rect rgb(200, 220, 255)
note over Server: Step 6
Server ->> Server: 💻 matches secrets received from 👩 and 👨
Server ->> Server: 💻 generates session key Ks 🔐
Server ->> Alice: 💻 sends session key Ks to 👩 ✉️
Server ->> Bob: 💻 sends session key Ks to 👨 ✉️
end
rect rgb(200, 220, 255)
note over Alice, Bob: Step 7
Alice ->> Alice: 👩 receives session key Ks from Server 🔐
Bob ->> Bob: 👨 receives session key Ks from Server 🔐
end
rect rgb(200, 220, 255)
note over Alice, Bob: Result
Alice ->> Bob: 👩 👨 can now communicate securely using session key Ks 🔐
end