156-215.77 · Question #410
Which statement defines Public Key Infrastructure? Security is provided:
The correct answer is C. By Certificate Authorities, digital certificates, and public key encryption. See the full explanation below for the reasoning.
Question
Which statement defines Public Key Infrastructure? Security is provided:
Options
- ABy authentication
- BBy Certificate Authorities, digital certificates, and two-way symmetric- key encryption
- CBy Certificate Authorities, digital certificates, and public key encryption.
- DVia both private and public keys, without the use of digital Certificates.
How the community answered
(33 responses)- A3% (1)
- B3% (1)
- C82% (27)
- D12% (4)
Community Discussion
9
Carlos M.Nov 18, 2025C is correct. PKI is built around Certificate Authorities that issue and manage digital certificates, which bind identities to public keys and enable asymmetric (public key) encryption, not symmetric key encryption like option B claims.
Prof. SaraNov 20, 2025Solid point, Carlos, and worth flagging for exam day that PKI does not replace symmetric encryption but rather secures the handoff of symmetric session keys, which is the hybrid model behind TLS and a reason this topic bridges the Cryptography and Network Security domains on the blueprint.
Prof. SaraNov 29, 2025PKI is exactly that, C, a framework built on Certificate Authorities that issue and sign digital certificates, using asymmetric (public key) encryption to bind an identity to a key pair. The trap in option B is "symmetric-key," which flips the entire model, since PKI lives and dies by asymmetric cryptography, not shared-secret encryption.
Anjali D.Nov 30, 2025Good callout on the B trap, and I would add that this is also where a lot of us conflate PKI with TLS as a whole, since TLS does use symmetric keys for the session after PKI handles the authentication piece, so the exam is really testing whether you can separate those two layers.
Amara A.Nov 26, 2025Sitting for 77 last spring I almost second-guessed myself on B because "symmetric" sounds plausible under exam pressure, but PKI is defined by asymmetric (public key) encryption paired with CAs and digital certificates, so C is the only tight definition. The moment I saw "two-way symmetric-key" in B I crossed it off, because if PKI used symmetric keys the whole point of the CA chain would collapse.
Yusuf A.Nov 28, 2025That is a solid catch on B, and what sealed it for me was remembering that the CA's job is specifically to bind a public key to an identity, which only makes sense in an asymmetric world where the public key can be freely shared without compromising the private key.
Yusuf A.Dec 3, 2025PKI is all about authentication, my senior drilled that into me.
Prof. SaraDec 3, 2025Yusuf, your senior is right that PKI handles authentication, but PKI is a full trust framework that also covers confidentiality, integrity, and non-repudiation through digital certificates and asymmetric key pairs, which is exactly why C is the more complete and correct answer here.
Anjali D.Dec 9, 2025Okay so I initially circled B because I kept reading "two-way symmetric-key encryption" and thinking, yeah that sounds thorough, but then I caught myself, PKI is literally built around asymmetric encryption, not symmetric, so that wording alone should have been a red flag. The whole point of PKI is that Certificate Authorities issue digital certificates that bind identities to public keys, and those public keys are part of an asymmetric system where you encrypt with one key and decrypt with the other. D throws you off by hinting at both key types but then removes digital certificates from the picture, which completely breaks the PKI model. Group consensus settled on C and I think that's solid, but does anyone want to weigh in on whether the exam has been known to word "public key encryption" in a way that could trip people up in other questions?