SSC CGL 2025 Tier-II · Paper-I, 19 January 2026 · Computer Knowledge Test · Question 5 of 150

We transcribed this text from the pictures of a candidate's response sheet for this paper; the answer is the key SSC marked with a green tick on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. This paper reaches us as a candidate's response sheet saved as pictures, so we transcribed the text from those pictures, and a second reader checked every question against them; where the layout carries meaning, we show the picture too. Each answer is the key SSC marked with a green tick on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. UnlockIAS wrote the solutions.

Which of the following is a secure method for encrypting emails to protect the content from unauthorized access?

(a)S/MIME
(b)IMAP
(c)SSL
(d)SMTP

Answer

Why

Correct — A. S/MIME (Secure/Multipurpose Internet Mail Extensions) secures the e-mail message itself. RFC 8551 lists what it provides: digital signatures for authentication, integrity and non-repudiation, and encryption for data confidentiality.

The sending mail program encrypts the message and the receiving one decrypts it, so the content stays protected on the way → option (a).

Why the others are wrong

(b)
IMAP — IMAP is for reading mail, not encrypting it. RFC 9051 says it lets a client access and manipulate e-mail messages on a server.
(c)
SSL — SSL protects a connection, not the message. RFC 3207 notes that adding TLS between one pair of mail servers does not make the whole chain private. SSL 3.0 is also deprecated by RFC 7568.
(d)
SMTP — SMTP transfers mail: RFC 5321 gives its objective as moving mail reliably and efficiently. It has no encryption of its own, and RFC 3207 adds TLS to it as an extension.

Concept

E-mail can be protected at two levels.

Transport security (SSL, now TLS) encrypts the connection between two machines, such as a mail program and its server, or two servers. RFC 3207 points out that mail may pass through more than two servers, so securing one pair does not secure the whole route.

Message security such as S/MIME encrypts the message itself, so it travels encrypted however many servers carry it. S/MIME also adds digital signatures, which prove who sent the message and that it was not altered.

SSL does encrypt mail traffic on a connection, which is why it tempts. The stem asks for protecting the content, and message-level encryption is what keeps content protected from sender to recipient.

Key facts

S/MIME stands for Secure/Multipurpose Internet Mail Extensions, and version 4.0 is defined in RFC 8551.
S/MIME gives confidentiality through encryption, and authentication, integrity and non-repudiation through digital signatures.
IMAP4rev2 (RFC 9051) listens on port 143, or on port 993 with implicit TLS.
RFC 7568 (June 2015) says SSL 3.0 is not sufficiently secure and must not be used.

Study next

TLS as the successor to SSL, and STARTTLS for SMTP (RFC 3207)Digital signatures and certificates in e-mailSymmetric against asymmetric encryption

Common traps

Choosing SSL because it is an encryption protocol, when it protects a connection rather than the message.
Treating SMTP or IMAP as security protocols, when they send and fetch mail and encryption is added to them separately.

Encryption is also tested at 19 Jan 2026, 11:00 AM, Computer Knowledge Q.15 (data in transit) and at 19 Jan 2026, 11:00 AM, Computer Knowledge Q.20 (the key-distribution problem of symmetric encryption).

Related PYQs

No directly related past PYQ was found.

Topic: Basics of networking and cyber security — all 6 SSC CGL questions on it, every solved shift.