CMSG_ENVELOPED_ENCODE_INFO

The CMSG_ENVELOPED_ENCODE_INFO structure is used for enveloped messages. This structure is passed to CryptMsgOpenToEncode for a value of CMSG_ENVELOPED in dwMsgType.

typedef struct _CMSG_ENVELOPED_ENCODE_INFO {
    DWORD                        cbSize;
    HCRYPTPROV                   hCryptProv;
    CRYPT_ALGORITHM_IDENTIFIER   ContentEncryptionAlgorithm;
    void*                        pvEncryptionAuxInfo;
    DWORD                        cRecipients;
    PCERT_INFO*                  rgpRecipients;
} CMSG_ENVELOPED_ENCODE_INFO,  *PCMSG_ENVELOPED_ENCODE_INFO;
 

Members

cbSize

The count of bytes in this data structure.

hCryptProv

Specifies a handle to the cryptographic service provider used to do the content encryption, recipient key encryption, and export. The hCryptProv's private keys aren't used.

Unless there is a strong reason for passing in a specific cryptographic provider in hCryptProv, zero should be passed in. Passing in zero causes the default RSA or DSS provider to be acquired before doing hash, signature verification or recipient encryption operations.

ContentEncryptionAlgorithm

Specifies the algorithm that is used to encrypt the contents.

The following encryption algorithms require that the ContentEncryptionAlgorithm's Parameters contain an encoded 8 byte Initialization Vector (IV) (see CryptSetKeyParam for more information about the KP_IV parameter).

szOID_OIWSEC_desCBC (CALG_DES)
szOID_RSA_DES_EDE3_CBC (CALG_3DES)
szOID_RSA_RC4 (CALG_RC4)

If the ContentEncryptionAlgorithm.Parameters.cbData = 0, then, an ASN.1 encoded OCTET STRING containing the IV is automatically generated. The IV is created using CryptGenRandom.

Note that when a message is decrypted, if it has an Initialization Vector parameter, the cryptographic message functions will call CryptSetKeyParam with the Initialization Vector before doing the decrypt.

The szOID_RSA_RC2CBC(CALG_RC2) algorithm requires the Parameters to be encoded as a CRYPT_RC2_CBC_PARAMETERS data structure. If the ContentEncryptionAlgorithm.Parameters.cbData = 0, then, an ASN.1 encoded CRYPT_RC2_CBC_PARAMETERS containing the IV is automatically generated, where the dwVersion corresponding to the 40 bit length is used for the default. To override the default 40 bit length, the pvEncryptionAuxInfo member can be used to point to a CMSG_RC2_AUX_INFO data structure which contains the bit length.

pvEncryptionAuxInfo

This parameter points to a CMSG_RC2_AUX_INFO data structure for RC2 encryption or a SMSG_SP3_COMPATIBLE_AUX_INFO data structure for SP3 compatible encryption. For anything other than RC2 or SP3 compatible encryption, pvEncryptionAuxInfo must be set to NULL.

cRecipients

The number of elements in the array rgpRecipients.

rgpRecipients

An array of structures, each holding recipient information. Provides the Issuer, SerialNumber, and SubjectPublicKeyInfo.

See Also

CERT_INFO, CRYPT_ALGORITHM_IDENTIFIER