Transport Encryption and Key Exchange

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• Transport/communication encryption protects data-in-motion
  • e.g.,
    • WPA
    • IPSec
    • TLS
• uses a system of key exchange
  • allows the sender and recipient to exchange a symmetric encryption key securely by using public key cryptography:
    1. Alice obtains a copy of Bob’s RSA or ECC public key, typically via Bob’s digital certificate.
    2. Alice encrypts their message using a secret key cipher, such as AES. In this context, the secret key is referred to as a session key.
    3. Alice encrypts the session key with Bob’s public key.
    4. Alice attaches the encrypted session key to the ciphertext message in a digital envelope and sends it to Bob.
    5. Bob uses their private key to decrypt the session key.
    6. Bob uses the session key to decrypt the ciphertext message.
       
• uses cryptography to ensure the integrity and authenticity of messages
  • via Hash-based Message Authentication Code (HMAC)
    • combines the secret key derived during key exchange with a hash of the message.
    • is a method used to verify both the integrity and authenticity of a message by combining a cryptographic hash of the message with a secret key

Info

Alternatively, the symmetric cipher might be designed to perform Authenticated Encryption (AE).

• This type of symmetric cipher mode of operation ensures confidentiality and integrity/authenticity.