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IObjectId::InitializeFromAlgorithmName method (certenroll.h)

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The InitializeFromAlgorithmName method initializes the object from an algorithm name or an object identifier. This method has been provided primarily to enable you to initialize the object from a Cryptography API: Next Generation (CNG) algorithm name. You can, however, specify any OID name. This method is web enabled.

Syntax

HRESULT InitializeFromAlgorithmName(
  [in] ObjectIdGroupId        GroupId,
  [in] ObjectIdPublicKeyFlags KeyFlags,
  [in] AlgorithmFlags         AlgFlags,
  [in] BSTR                   strAlgorithmName
);

Parameters

[in] GroupId

An ObjectIdGroupId enumeration value that specifies the OID group to search. This can be any of the following algorithm groups:

  • XCN_CRYPT_HASH_ALG_OID_GROUP_ID
  • XCN_CRYPT_ENCRYPT_ALG_OID_GROUP_ID
  • XCN_CRYPT_PUBKEY_ALG_OID_GROUP_ID
  • XCN_CRYPT_SIGN_ALG_OID_GROUP_ID
In addition, you can also specify groups that do not contain cryptographic algorithms:
  • XCN_CRYPT_RDN_ATTR_OID_GROUP_ID
  • XCN_CRYPT_EXT_OR_ATTR_OID_GROUP_ID
  • XCN_CRYPT_ENHKEY_USAGE_OID_GROUP_ID
  • XCN_CRYPT_POLICY_OID_GROUP_ID
  • XCN_CRYPT_TEMPLATE_OID_GROUP_ID

[in] KeyFlags

An ObjectIdPublicKeyFlags enumeration value that specifies whether to search for a signing or an encryption algorithm. This can be one of the following values:

  • XCN_CRYPT_OID_INFO_PUBKEY_SIGN_KEY_FLAG
  • XCN_CRYPT_OID_INFO_PUBKEY_ENCRYPT_KEY_FLAG
You can use either value to disambiguate among algorithms such as RSA that can be used to both encrypt and sign messages. You must also specify XCN_CRYPT_PUBKEY_ALG_OID_GROUP_ID in the GroupId parameter.

[in] AlgFlags

An AlgorithmFlags enumeration value. This can be one of the following values:

  • AlgorithmFlagsNone
  • AlgorithmFlagsWrap
If you specify XCN_CRYPT_ENCRYPT_ALG_OID_GROUP_ID for the GroupId parameter, you can use the AlgorithmFlags enumeration to search for an OID that can be used to wrap a key. For example, you can retrieve information about the AES128wrap algorithm if you specify a bit length of 128 (see the Remarks section), set the strAlgorithmName parameter to AES, and specify AlgorithmFlagsWrap.

[in] strAlgorithmName

A BSTR variable that contains the name. You can specify a name, or an OID in dotted decimal format. The method verifies that the format is consistent with the ASN.1 X.208 standard. For more information about CNG algorithm names, see CNG Algorithm Identifiers.

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/value Description
CERTSRV_E_PROPERTY_EMPTY
 The OID information could not be found.
CRYPT_E_UNKNOWN_ALGO
 The algorithm name is not recognized.
HRESULT_FROM_WIN32(ERROR_ALREADY_INITIALIZED)
 The object is already initialized.

Remarks

You can use the upper 16 bits of the GroupId parameter to specify the key size for algorithms that accept a variable bit length. For example, to initialize an IObjectId object from a 192-bit AES algorithm, specify "AES" for the strAlgorithmName parameter, shift the length left by 16, and perform a bitwise-OR combination on the shifted bit length and the GroupId value.

Requirements

Requirement Value
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

IObjectId