E2-E2 Encryption: [Ephemeral-to-Ephemeral] - [End-to-End]

Overview:

E2-E2 encryption is a layered security protocol designed to establish an ephemeral-to-ephemeral encrypted channel between a client and server. The process involves two stages of key generation to ensure high-level security and forward secrecy.

Process:

1. K1 (Initial Key Exchange):

   • Client and Server generate their own ECDH Curve25519 Public/Private Key Pairs.
   • These public keys are exchanged between the client and server, allowing the generation of a shared secret K1 through the Diffie-Hellman process.
   • K1 establishes a secure End-to-End (E2E) encrypted channel for communication.

2. K2 (Ephemeral Key Generation):

   • Once the secure channel is established with K1, both the client and server use their knowledge of K1 and the Ephemeral API Key (EAPI) to generate a new key, K2.
   • K2 is derived by hashing or using a Key Derivation Function (KDF) on K1 and the API Key (a pre-shared key known only to the client and server).

3. K3 (Key Combination):

   • K2 is then used to derive K3, a key that becomes the primary secret for all future communications.
   • K3 is derived without additional key exchanges, ensuring that even if K1 is compromised, K3 remains secure.
   • K3 is generated independently by both the client and server using a combination of K1 and the API Key, with no need for further transmissions.

4. Use of K3:

   • K3 becomes the full secret key for both the client and server, handling all encrypted communication going forward.
   • This key can also be used to dynamically generate Ephemeral API Keys (EAPI) for session-based operations or further authentication.
   • With K3, both the client and server maintain a secure, shared secret for all communication without the need for additional exchanges.

Benefits:

• Forward Secrecy: Compromise of K1 does not expose K3, as K3 is derived using information that is not transmitted.
• Ephemeral Security: By deriving K2 and K3 from K1 and the API Key, the protocol ensures that each communication session is independent and secure.
• Dynamic API Keys: K3 can be used to generate session-based API keys, adding another layer of security for authenticated requests.