S/MIME

E37201

IETF standard cryptographic protocol email security standard

S/MIME is a widely used standard for secure email that provides encryption and digital signatures using public key cryptography.

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All labels observed (23)

Label	Occurrences
S/MIME canonical	31
Secure/Multipurpose Internet Mail Extensions	4
S/MIME Version 3.1	3
S/MIME Version 3	2
S/MIME Version 3.2	2
S/MIME Working Group	2
S/MIME message format	2
S/MIME security services	2
CMS (Cryptographic Message Syntax)	1
IETF Cryptographic Message Syntax	1
S/MIME Version 2	1
S/MIME Version 2 Message Specification	1
S/MIME Version 3 Message Specification	1
S/MIME Version 3.2 specification	1
S/MIME Version 4.0	1
S/MIME capabilities attribute	1
S/MIME media types	1
S/MIME v3	1
S/MIME v3.1	1
S/MIME v4.0	1
Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message Specification	1
Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message Specification	1
Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 4.0 Message Specification	1

How this entity was disambiguated

This entity first appeared as the object of triple T287236 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.

NED1 Entity disambiguation (via context triple) gpt-5-mini-2025-08-07

Target entity: S/MIME
Context triple: [RSA, usedInProtocol, S/MIME]

A. PGP
PGP (Pretty Good Privacy) is an encryption program that provides cryptographic privacy and authentication for data communication, most notably for securing emails and files.
B. X.509 certificates
X.509 certificates are digital documents that bind a public key to an entity’s identity using a trusted certificate authority, forming the basis of public key infrastructure for secure communications.
C. TLS
TLS (Transport Layer Security) is a cryptographic protocol that secures data transmitted over networks by providing encryption, authentication, and integrity between communicating applications.
D. SSL
SSL (Secure Sockets Layer) is a cryptographic protocol designed to provide secure, encrypted communication over a computer network, commonly used to protect data transmitted between clients and servers.
E. SMTP
SMTP (Simple Mail Transfer Protocol) is a standard communication protocol used for sending and routing email messages across IP networks.
F. None of above. chosen
G. Unsure - the case is ambiguous/there is not enough information to decide.

NED2 Entity disambiguation (via description) gpt-5-mini-2025-08-07

Target entity: S/MIME
Target entity description: S/MIME is a widely used standard for secure email that provides encryption and digital signatures using public key cryptography.

A. PGP
PGP (Pretty Good Privacy) is an encryption program that provides cryptographic privacy and authentication for data communication, most notably for securing emails and files.
B. X.509 certificates
X.509 certificates are digital documents that bind a public key to an entity’s identity using a trusted certificate authority, forming the basis of public key infrastructure for secure communications.
C. TLS
TLS (Transport Layer Security) is a cryptographic protocol that secures data transmitted over networks by providing encryption, authentication, and integrity between communicating applications.
D. SSL
SSL (Secure Sockets Layer) is a cryptographic protocol designed to provide secure, encrypted communication over a computer network, commonly used to protect data transmitted between clients and servers.
E. SMTP
SMTP (Simple Mail Transfer Protocol) is a standard communication protocol used for sending and routing email messages across IP networks.
F. None of above. chosen

Statements (50)

Predicate	Object
instanceOf	IETF standard ⓘ cryptographic protocol ⓘ email security standard ⓘ
basedOn	MIME ⓘ
compatibleWith	IMAP ⓘ POP3 ⓘ SMTP ⓘ
competesWith	OpenPGP ⓘ linked to: PGP
definedIn	RFC 5751 ⓘ RFC 8551 ⓘ
extends	MIME ⓘ
fullName	Secure/Multipurpose Internet Mail Extensions ⓘ linked to: S/MIME
goal	authenticity of sender ⓘ confidentiality of email ⓘ integrity of email ⓘ interoperable secure email ⓘ
operatesAt	application layer ⓘ
protects	email attachments ⓘ email message body ⓘ
provides	digital signatures ⓘ email encryption ⓘ message authentication ⓘ message integrity ⓘ non-repudiation ⓘ
requires	Public Key Infrastructure ⓘ linked to: X.509 certificates trusted Certificate Authorities ⓘ
standardizedBy	IETF ⓘ linked to: Internet Engineering Task Force
supportedBy	Apple Mail ⓘ linked to: Mail Microsoft Outlook ⓘ linked to: Outlook Mozilla Thunderbird ⓘ linked to: Thunderbird email client many mobile email clients ⓘ
supports	certificate chains ⓘ certificate revocation lists ⓘ certificate-based authentication ⓘ end-to-end email encryption ⓘ key management via certificates ⓘ signing of email messages ⓘ
usedIn	commercial email clients ⓘ corporate email systems ⓘ government email systems ⓘ
uses	CMS (Cryptographic Message Syntax) ⓘ linked to: S/MIME PKCS #7 ⓘ X.509 certificates ⓘ asymmetric encryption for key exchange ⓘ hash functions for signatures ⓘ public key cryptography ⓘ symmetric encryption for message content ⓘ
version	S/MIME v3 ⓘ linked to: S/MIME S/MIME v3.1 ⓘ linked to: S/MIME S/MIME v4.0 ⓘ linked to: S/MIME

How these facts were elicited

Referenced by (63)

Full triples — surface form annotated when it differs from this entity's canonical label.

RSA → usedInProtocol → S/MIME ⓘ

X.509 certificate → usedInProtocol → S/MIME ⓘ

subject linked to: X.509 certificates

PKCS #1 → usedIn → S/MIME ⓘ

RFC 8017 → relatedTo → S/MIME ⓘ

S/MIME → fullName → Secure/Multipurpose Internet Mail Extensions ⓘ

linked to: S/MIME

S/MIME → uses → CMS (Cryptographic Message Syntax) ⓘ

linked to: S/MIME

S/MIME → version → S/MIME v3 ⓘ

linked to: S/MIME

S/MIME → version → S/MIME v3.1 ⓘ

linked to: S/MIME

S/MIME → version → S/MIME v4.0 ⓘ

linked to: S/MIME

ASN.1 → usedIn → S/MIME ⓘ

GNU Privacy Guard → supportsStandard → S/MIME ⓘ

Werner Koch → supportsStandard → S/MIME ⓘ

RC2 → usedIn → S/MIME ⓘ

RFC 8551 → title → Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 4.0 Message Specification ⓘ

linked to: S/MIME

RFC 8551 → protocolSpecified → S/MIME ⓘ

RFC 8551 → specifiesVersion → S/MIME Version 4.0 ⓘ

linked to: S/MIME

RFC 8551 → defines → S/MIME message format ⓘ

linked to: S/MIME

RFC 8551 → defines → S/MIME security services ⓘ

linked to: S/MIME

RFC 8551 → defines → S/MIME media types ⓘ

linked to: S/MIME

RFC 8551 → relatedTo → S/MIME Version 3.2 ⓘ

linked to: S/MIME

OpenSSL → implementsStandard → S/MIME ⓘ

PKCS #7 → basisFor → S/MIME ⓘ

PKCS #7 → influenced → IETF Cryptographic Message Syntax ⓘ

linked to: S/MIME

RFC 5751 → title → Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.2 Message Specification ⓘ

linked to: S/MIME

RFC 5751 → abbreviation → S/MIME Version 3.2 ⓘ

linked to: S/MIME

RFC 5751 → protocolSpecified → Secure/Multipurpose Internet Mail Extensions ⓘ

linked to: S/MIME

RFC 5751 → protocolAbbreviation → S/MIME ⓘ

RFC 5751 → updates → S/MIME Version 3.1 ⓘ

linked to: S/MIME

RFC 5751 → workingGroup → S/MIME Working Group ⓘ

linked to: S/MIME

RFC 5751 → topic → Secure/Multipurpose Internet Mail Extensions ⓘ

linked to: S/MIME

gpgsm → implements → S/MIME ⓘ

gpgsm → supportsStandard → S/MIME ⓘ

Gpg4win → supportsStandard → S/MIME ⓘ

Gpg4win → implementsProtocol → S/MIME ⓘ

Mozilla Messaging → supportsStandard → S/MIME ⓘ

Base64 → usedIn → S/MIME ⓘ

Session Initiation Protocol → supportsSecurityMechanism → S/MIME ⓘ

Thunderbird project → supportsOpenStandards → S/MIME ⓘ

PGP Corporation → implements → S/MIME ⓘ

Lamps Working Group → relatedTo → S/MIME Working Group ⓘ

linked to: S/MIME

RFC 8553 → relatedTo → S/MIME ⓘ

RFC 3851 → title → Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message Specification ⓘ

linked to: S/MIME

RFC 3851 → definesVersionOf → S/MIME Version 3.1 ⓘ

linked to: S/MIME

RFC 3851 → specifies → S/MIME message format ⓘ

linked to: S/MIME

RFC 3851 → defines → S/MIME capabilities attribute ⓘ

linked to: S/MIME

RFC 3851 → obsoletedBy → S/MIME Version 3.2 specification ⓘ

linked to: S/MIME

RFC 3851 → relatedTo → S/MIME ⓘ

Public-Key Cryptography Standards #7 → isBasisFor → S/MIME ⓘ

Cryptographic Message Syntax → usedIn → S/MIME ⓘ

subject linked to: CMS

Cryptographic Message Syntax → relatedStandard → S/MIME ⓘ

subject linked to: CMS

All labels observed (23)

How this entity was disambiguated Show

Statements (50)

How these facts were elicited Show

Referenced by (63)

How this entity was disambiguated

How these facts were elicited