Confidentiality, integrity, and authentication. Confidentiality means the data is encrypted so eavesdroppers on the path see only ciphertext, achieved with symmetric encryption using keys agreed during the handshake. Integrity means any tampering with the data in transit is detected and the modified data rejected, achieved with message authentication codes / AEAD ciphers that bind a cryptographic tag to each record. Authentication means each side can verify it's talking to the genuine peer rather than an impostor, achieved with certificates: the server presents a certificate the client validates against trusted certificate authorities, and with mutual TLS the device presents its own certificate the server validates. The mechanism that ties it together is the handshake, which uses asymmetric (public-key) cryptography to authenticate the peer and securely agree on a shared secret, then switches to fast symmetric crypto for the bulk data. Without authentication the other two are nearly worthless, you could have a perfectly encrypted, tamper-proof channel to an attacker, which is why certificate validation is the part you must never skip.
Networking & IoT · Interview question
What three guarantees does TLS provide, and how?
A strong answer
What a weak answer sounds like
You know the answer. Do you know what gets you dinged?
Pro breaks down the answer most candidates actually give to this question — and the specific reason an interviewer marks it down. It’s the difference between sounding correct and sounding senior, on all 472 questions.
From the lesson
TLS & Certificates
Securing a connection: TLS gives confidentiality, integrity, and authentication via a handshake; certificates and PKI prove identity; and mutual TLS gives each device its own identity, at a real cost on MCUs.