A class for verifying and creating PKCS10 Certification requests.

CertificationRequest ::= SEQUENCE {
  certificationRequestInfo  CertificationRequestInfo,
  signatureAlgorithm        AlgorithmIdentifier{{ SignatureAlgorithms }},
  signature                 BIT STRING
}

CertificationRequestInfo ::= SEQUENCE {
  version             INTEGER { v1(0) } (v1,...),
  subject             Name,
  subjectPKInfo   SubjectPublicKeyInfo{{ PKInfoAlgorithms }},
  attributes          [0] Attributes{{ CRIAttributes }}
 }

 Attributes { ATTRIBUTE:IOSet } ::= SET OF Attribute{{ IOSet }}

 Attribute { ATTRIBUTE:IOSet } ::= SEQUENCE {
   type    ATTRIBUTE.&id({IOSet}),
   values  SET SIZE(1..MAX) OF ATTRIBUTE.&Type({IOSet}{\@type})
 }