CMSG_SIGNER_ENCODE_INFO structure (wincrypt.h)

The CMSG_SIGNER_ENCODE_INFO structure contains signer information. It is passed to CryptMsgCountersign, CryptMsgCountersignEncoded, and optionally to CryptMsgOpenToEncode as a member of the CMSG_SIGNED_ENCODE_INFO structure, if the dwMsgType parameter is CMSG_SIGNED.

Syntax

typedef struct _CMSG_SIGNER_ENCODE_INFO {
  DWORD                      cbSize;
  PCERT_INFO                 pCertInfo;
  union {
    HCRYPTPROV        hCryptProv;
    NCRYPT_KEY_HANDLE hNCryptKey;
    BCRYPT_KEY_HANDLE hBCryptKey;
  } DUMMYUNIONNAME;
  DWORD                      dwKeySpec;
  CRYPT_ALGORITHM_IDENTIFIER HashAlgorithm;
  void                       *pvHashAuxInfo;
  DWORD                      cAuthAttr;
  PCRYPT_ATTRIBUTE           rgAuthAttr;
  DWORD                      cUnauthAttr;
  PCRYPT_ATTRIBUTE           rgUnauthAttr;
  CERT_ID                    SignerId;
  CRYPT_ALGORITHM_IDENTIFIER HashEncryptionAlgorithm;
  void                       *pvHashEncryptionAuxInfo;
} CMSG_SIGNER_ENCODE_INFO, *PCMSG_SIGNER_ENCODE_INFO;

Members

cbSize

The size, in bytes, of this structure.

pCertInfo

A pointer to a CERT_INFO structure that contains the

Issuer, SerialNumber, and SubjectPublicKeyInfo members.

The pbData members of the Issuer and SerialNumber structures combined uniquely identify a certificate. The Algorithm member of the SubjectPublicKeyInfo structure specifies the hash encryption algorithm used.

DUMMYUNIONNAME

DUMMYUNIONNAME.hCryptProv

A handle to the cryptographic service provider (CSP). If HashEncryptionAlgorithm is set to szOID_PKIX_NO_SIGNATURE, this handle can be the handle of a CSP acquired by using the dwFlags parameter set to CRYPT_VERIFYCONTEXT. The CNG function NCryptIsKeyHandle is called to determine the union choice.

DUMMYUNIONNAME.hNCryptKey

A handle to the CNG CSP. The CNG function NCryptIsKeyHandle is called to determine the union choice. New encrypt algorithms are only supported in CNG functions. The CNG function NCryptTranslateHandle will be called to convert the CryptoAPI hCryptProv choice where necessary. We recommend that applications pass, to the hNCryptKey member, the CNG CSP handle that is returned from the NCryptOpenKey function.

DUMMYUNIONNAME.hBCryptKey

dwKeySpec

Specifies the private key to be used. This member is not used when the hNCryptKey member is used.

If dwKeySpec is zero, then the default AT_KEYEXCHANGE value is used.

The following dwKeySpec values are defined for the default provider.

HashAlgorithm

A CRYPT_ALGORITHM_IDENTIFIER structure that specifies the hash algorithm.

pvHashAuxInfo

Not used. This member must be set to NULL.

cAuthAttr

The number of elements in the rgAuthAttr array. If no authenticated attributes are present in rgAuthAttr, then cAuthAttr is zero.

rgAuthAttr

An array of pointers to CRYPT_ATTRIBUTE structures, each of which contains authenticated attribute information.

The PKCS #9 standard dictates that if there are any attributes, there must be at least two: the content type object identifier (OID) and the hash of the message. These attributes are automatically added by the system.

cUnauthAttr

The number of elements in the rgUnauthAttr array. If there are no unauthenticated attributes, cUnauthAttr is zero.

rgUnauthAttr

An array of pointers to CRYPT_ATTRIBUTE structures, each of which contains unauthenticated attribute information. Unauthenticated attributes can contain countersignatures, among other uses.

SignerId

A CERT_ID structure that contains a unique identifier of the signer's certificate. This member can optionally be used with PKCS #7 with Cryptographic Message Syntax (CMS). If this member is not NULL and its dwIdChoice member is not zero, it is used to identify the certificate instead of the Issuer and SerialNumber members of the CERT_INFO structure pointed to by pCertInfo. CMS supports the KEY_IDENTIFIER and ISSUER_SERIAL_NUMBER CERT_ID structures. PKCS version 1.5 supports only the ISSUER_SERIAL_NUMBER CERT_ID choice. This member is used with CMS for PKCS #7 processing and can be used only if CMSG_SIGNER_ENCODE_INFO_HAS_CMS_FIELDS is defined.

HashEncryptionAlgorithm

A CRYPT_ALGORITHM_IDENTIFIER structure optionally used with PKCS #7 with CMS. If this member is not NULL, the algorithm identified is used instead of the SubjectPublicKeyInfo.Algorithm algorithm. If this member is set to szOID_PKIX_NO_SIGNATURE, the signature value contains only the hash octets.

For RSA, the hash encryption algorithm is normally the same as the public key algorithm. For DSA, the hash encryption algorithm is normally a DSS signature algorithm.

This member is used with CMS for PKCS #7 processing and can be used only if CMSG_SIGNER_ENCODE_INFO_HAS_CMS_FIELDS is defined.

pvHashEncryptionAuxInfo

This member is not used. This member must be set to NULL if it is present in the data structure. This member is present only if CMSG_SIGNER_ENCODE_INFO_HAS_CMS_FIELDS is defined.

Requirements

See also

CERT_INFO

CRYPT_ALGORITHM_IDENTIFIER

CRYPT_ATTRIBUTE

CryptMsgControl

CryptMsgCountersign