%%{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 
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