Entrust provides the following S/MIME Secure Email certificate profiles.

  • smime-digital-signature-key-encipherment
  • smime-key-encipherment
  • smime-non-repudiation

These profiles support the following features.

S/MIME use cases

All S/MIME Secure Email profiles support the following use cases.

  • ECS Enterprise UI
  • CA Gateway API

S/MIME key usages

See below the Key Usage and Extended Key Usage (EKU) extension values each profile supports.

Profile

Key Usage

Extended Key Usage

smime-digital-signature-key-encipherment

Digital Signature, Key Encipherment

TLS client authentication (1.3.6.1.5.5.7.3.2)

Email Protection (1.3.6.1.5.5.7.3.4)

smime-key-encipherment

Key Encipherment

Email Protection (1.3.6.1.5.5.7.3.4)

smime-non-repudiation

Digital Signature, Non-Repudiation

Email Protection (1.3.6.1.5.5.7.3.4)

S/MIME certificate fields

All S/MIME Secure Email profiles set the following certificate fields.

Field

Value

Issuer

Customer's subordinate issuing CA.

Subject

No constraint.

Validity period

Less than or equal to the expiry of the issuing CA. Defaults to 1 year if not specified in the request.

S/MIME certificate extensions

All S/MIME Secure Email profiles set the following certificate extensions.

Extension

Critical

Value

AIA

No

Supplied if the customer enables OCSP when creating the CA

Authority Key Identifier

No

Matches subjectKeyIdentifier of the signing certificate

Basic Constraints

Yes

cA =False

CRL Distribution Points

No

Always present

Subject Alternative Name

No

No constraints

Subject Key Identifier

No

«The leftmost 160-bits of the SHA-256 hash of the value of the BIT STRING subjectPublicKey» as described in RFC 7093 section 2

S/MIME algorithm constraints

All S/MIME Secure Email profiles support the following key and signature algorithms.

Key algorithm

Signature algorithm

ECDSA P-256

ecdsa-with-SHA256

ECDSA P-384

ecdsa-with-SHA384

ECDSA P-521

ecdsa-with-SHA512

RSA 2048

sha256WithRSAEncryption

RSA 3072

sha256WithRSAEncryption

RSA 4096

sha512WithRSAEncryption

The NIST will deprecate some algorithms after Dec 31, 2030. See https://nvlpubs.nist.gov/nistpubs/ir/2024/NIST.IR.8547.ipd.pdf

S/MIME distinguished names

Entrust has no restriction on Distinguished Names (DNs) per certificate profile. All certificate profiles support the following identifiers.

Alias

OID

'CN' 'CommonName'

2.5.4.3

'SN' 'SurName'

2.5.4.4

'SERIALNUMBER' 'DeviceSerialNumber'

2.5.4.5

'C' 'Country'

2.5.4.6

'L' 'Locality'

2.5.4.7

'ST' 'S' 'State'

2.5.4.8

'STREET' 'StreetAddress'

2.5.4.9

'O' 'Org' 'Organization'

2.5.4.10

'OU' 'OrganizationalUnit' 'OrganizationUnit' 'OrgUnit'

2.5.4.11

'T' 'Title'

2.5.4.12

'BUSINESSCATEGORY'

2.5.4.15

'POSTALCODE'

2.5.4.17

'givenName' 'G'

2.5.4.42

'I' 'Initials'

2.5.4.43

'ORGANIZATIONIDENTIFIER'

2.5.4.97

'UID'

0.9.2342.19200300.100.1.1

'DC' 'DomainComponent'

0.9.2342.19200300.100.1.25

'Email' 'E'

1.2.840.113549.1.9.1

'unstructuredName'

1.2.840.113549.1.9.2

'unstructuredAddress'

1.2.840.113549.1.9.8

'JurisdictionOfIncorporationLocalityName'

1.3.6.1.4.1.311.60.2.1.1

'JurisdictionOfIncorporationStateOrProvinceName'

1.3.6.1.4.1.311.60.2.1.2

'JurisdictionOfIncorporationCountryName'

1.3.6.1.4.1.311.60.2.1.3

'TrademarkOfficeName'

1.3.6.1.4.1.53087.1.2

'TrademarkCountryOrRegionName'

1.3.6.1.4.1.53087.1.3

'TrademarkRegistration'

1.3.6.1.4.1.53087.1.4

'LegalEntityIdentifier'

1.3.6.1.4.1.53087.1.5

'WordMark'

1.3.6.1.4.1.53087.1.6

'MarkType'

1.3.6.1.4.1.53087.1.13

'StatuteCountryName'

1.3.6.1.4.1.53087.3.2

'StatuteStateOrProvinceName'

1.3.6.1.4.1.53087.3.3

'StatuteLocalityName'

1.3.6.1.4.1.53087.3.4

'StatuteCitation'

1.3.6.1.4.1.53087.3.5

'StatuteURL'

1.3.6.1.4.1.53087.3.6