SIGMA

SIGMA¶

• Just Diffie Hellman with Signing and MACing
• Used in IKE and IPsec protocols
  • Uses pretrusted Static Keys for authentication

1. Alice Sends Bob g^x
2. Bob Sends g^y and proof of x and y encrypted
   • Bob Generates the g^xy Shared key
   • Bob uses that key to encrypt the data sent to Alice
     • This data includes a Public Key
     • The signature of g^x and g^y using the provided public Key
     • The MAC of the Public Key
3. Alice sends proof of x and y encrypted
   • Alice Generates the g^xy Shared key
   • Alice uses that key to encrypt the data sent to Bob
     • This data includes a Public Key
     • The signature of g^y and g^x using the provided public Key
     • The MAC of the Public Key

https://crypto.stackexchange.com/questions/87060/mac-then-encrypt-in-sigma-protocol-for-authenticated-key-exchange

Implementation¶