Which email encryption tool uses its own digital certificates rather than CA-issued ones?

Which email encryption tool uses its own digital certificates rather than CA-issued ones?

• A. PGP
• B. S/MIME
• C. SSL
• D. HTTPS

Answer: (A)

The key idea is the trust model behind the email encryption tool. PGP relies on a decentralized web of trust: each user creates a public/private key pair, shares the public key, and others can sign or certify that key to assert identity. These key signatures act like certificates, but they are created and managed by users themselves rather than issued by a central authority. This means PGP uses its own certificates built from user verification and signatures, not CA-issued ones. In contrast, S/MIME depends on a traditional PKI where certificates are issued by trusted certificate authorities and then vouched for through a CA chain. SSL and HTTPS are protocols that use TLS with server certificates from CAs, not email-specific encryption tools, so they follow the CA-based model as well. So, the option that uses its own digital certificates rather than CA-issued ones is PGP.

The key idea is the trust model behind the email encryption tool. PGP relies on a decentralized web of trust: each user creates a public/private key pair, shares the public key, and others can sign or certify that key to assert identity. These key signatures act like certificates, but they are created and managed by users themselves rather than issued by a central authority. This means PGP uses its own certificates built from user verification and signatures, not CA-issued ones.

In contrast, S/MIME depends on a traditional PKI where certificates are issued by trusted certificate authorities and then vouched for through a CA chain. SSL and HTTPS are protocols that use TLS with server certificates from CAs, not email-specific encryption tools, so they follow the CA-based model as well.

So, the option that uses its own digital certificates rather than CA-issued ones is PGP.