IX509CertificateRequestPkcs10::InitializeFromCertificate method (certenroll.h)

The InitializeFromCertificate method initializes the certificate request by using an existing certificate. The certificate is contained in a byte array encoded by using Distinguished Encoding Rules (DER) as defined by the Abstract Syntax Notation One (ASN.1) standard. The DER-encoded byte array is represented by a string that is either a pure binary sequence or is Unicode encoded.

Syntax

HRESULT InitializeFromCertificate(
  X509CertificateEnrollmentContext Context,
  BSTR                             strCertificate,
  EncodingType                     Encoding,
  X509RequestInheritOptions        InheritOptions
);

Parameters

Context

An X509CertificateEnrollmentContext enumeration value that specifies whether the requested certificate is intended for an end user, a computer, or an administrator acting on behalf of the computer.

strCertificate

A BSTR variable that contains the DER-encoded certificate.

Beginning with Windows 7 and Windows Server 2008 R2, you can specify a certificate thumb print or serial number rather than an encoded certificate. Doing so causes the function to search the appropriate local stores for the matching certificate. Keep in mind the following points:

  • The BSTR must be an even number of hexadecimal digits.
  • Whitespace between hexadecimal pairs is ignored.
  • The Encoding parameter must be set to XCN_CRYPT_STRING_HEXRAW.
  • The Context parameter determines whether the user or computer stores or both are searched.
  • If a private key is needed, only the personal and request stores are searched.
  • If a private key is not needed, the root and intermediate CA stores are also searched.

Encoding

An EncodingType enumeration value that specifies the type of Unicode encoding applied to the DER-encoded certificate. The default value is XCN_CRYPT_STRING_BASE64.

InheritOptions

An X509RequestInheritOptions enumeration value that specifies how to create the certificate request object from the existing certificate. You can specify how to inherit a key by choosing one of the following values. The default value is InheritDefault.

Value Meaning
InheritDefault
Provider and key inheritance is not specified.
InheritNewDefaultKey
Creates a new key but inherits the default cryptographic provider.
InheritNewSimilarKey
Creates a new key but inherits the cryptographic provider used to create the existing certificate.
InheritPrivateKey
Inherits the private and public keys.
InheritPublicKey
Inherits only the public key.
 

You can also use a bitwise-OR operation to combine the key inheritance value with any combination of the following values.

Value Meaning
InheritRenewalCertificateFlag
Inherits the renewal certificate. Specifying this flag sets the RenewalCertificate property.
InheritTemplateFlag
Inherits the certificate template.
InheritSubjectFlag
Inherits the subject distinguished name.
InheritExtensionsFlag
Inherits the relevant extensions from the certificate.
InheritSubjectAltNameFlag
Inherits the SubjectAlternativeName extension.
InheritValidityPeriodFlag
Inherits the validity period.
 

You can also specify InheritNone to prevent any of the flags in the preceding table (flags not related to key inheritance) from being implemented by default. If you specify InheritNone but also specify a flag not related to key inheritance, the method returns E_INVALIDARG.

If you set the InheritOptions parameter to zero (0) or specify InheritDefault and do not specify a key inheritance value, InheritNewSimilarKey is used by default.

If you set the InheritOptions parameter to zero (0) or specify InheritDefault and do not specify any of the values not related to key inheritance, the following flags are set by default:

  • InheritSubjectFlag
  • InheritExtensionsFlag
  • InheritValidityPeriodFlag
  • InheritTemplateFlag (if the certificate contains a template extension)

Return value

If the function succeeds, the function returns S_OK.

If the function fails, it returns an HRESULT value that indicates the error. Possible values include, but are not limited to, those in the following table. For a list of common error codes, see Common HRESULT Values.

Return code Description
HRESULT_FROM_WIN32(ERROR_ALREADY_INITIALIZED)
The certificate request object has already been initialized.

Remarks

The InitializeFromCertificate method validates the options specified in the InheritOptions parameter and initializes a new PKCS #10 request object by performing the following actions:

  • Copies the renewal certificate, if there is one and you have specified InheritRenewalCertificateFlag, from the input certificate to the new request.
  • Copies the template if one is specified in the existing certificate and you set the InheritTemplateFlag value.
  • Copies the subject distinguished name to the new request if you specify InheritSubjectFlag.
  • Copies the subject alternative name to the new request if you specify InheritSubjectAltNameFlag.
  • Copies the extensions to the new request if you specify InheritExtensionsFlag.

Requirements

   
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Target Platform Windows
Header certenroll.h
DLL CertEnroll.dll

See also

IX509CertificateRequestPkcs10