Basic certificate fields

Basic Certificate Fields

  The X.509 v3 certificate basic syntax is as follows.  For signature
  calculation, the certificate is encoded using the ASN.1 distinguished
  encoding rules (DER) [X.208].  ASN.1 DER encoding is a tag, length,
  value encoding system for each element.

  Certificate  ::=  SEQUENCE  {
       tbsCertificate       TBSCertificate,
       signatureAlgorithm   AlgorithmIdentifier,
       signatureValue       BIT STRING  }

  TBSCertificate  ::=  SEQUENCE  {
       version         [0]  EXPLICIT Version DEFAULT v1,
       serialNumber         CertificateSerialNumber,
       signature            AlgorithmIdentifier,
       issuer               Name,
       validity             Validity,
       subject              Name,
       subjectPublicKeyInfo SubjectPublicKeyInfo,
       issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                            -- If present, version shall be v2 or v3
       subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                            -- If present, version shall be v2 or v3
       extensions      [3]  EXPLICIT Extensions OPTIONAL
                            -- If present, version shall be v3
       }
  Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }

  CertificateSerialNumber  ::=  INTEGER

  Validity ::= SEQUENCE {
       notBefore      Time,
       notAfter       Time }

  Time ::= CHOICE {
       utcTime        UTCTime,
       generalTime    GeneralizedTime }

  UniqueIdentifier  ::=  BIT STRING

  SubjectPublicKeyInfo  ::=  SEQUENCE  {
       algorithm            AlgorithmIdentifier,
       subjectPublicKey     BIT STRING  }

  Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension

  Extension  ::=  SEQUENCE  {
       extnID      OBJECT IDENTIFIER,
       critical    BOOLEAN DEFAULT FALSE,
       extnValue   OCTET STRING  }