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NAME

CMS_get0_type, CMS_set1_eContentType, CMS_get0_eContentType, CMS_get0_content — get and set CMS content types and content

SYNOPSIS

#include <openssl/cms.h>

const ASN1_OBJECT *
CMS_get0_type(const CMS_ContentInfo *cms);

int
CMS_set1_eContentType(CMS_ContentInfo *cms, const ASN1_OBJECT *oid);

const ASN1_OBJECT *
CMS_get0_eContentType(CMS_ContentInfo *cms);

ASN1_OCTET_STRING **
CMS_get0_content(CMS_ContentInfo *cms);

DESCRIPTION

CMS_get0_type() returns the content type of the ContentInfo structure cms. The ASN1_OBJECT value returned can be converted to an integer NID value using OBJ_obj2nid(3). The following content types are identified by the following NIDs:

SignedData	NID_pkcs7_signed
EnvelopedData	NID_pkcs7_enveloped
DigestedData	NID_pkcs7_digest
EncryptedData	NID_pkcs7_encrypted
AuthenticatedData	NID_id_smime_ct_authData
CompressedData	NID_id_smime_ct_compressedData
arbitrary data	NID_pkcs7_data

The SignedData, DigestedData, AuthenticatedData, and CompressedData types contain a field encapContentInfo to allow embedding content, and EnvelopedData and EncryptedData contain a field encryptedContentInfo for that purpose. The type of the embedded content to be stored in that field can be set with the function CMS_set1_eContentType(), to be called on cms structures returned from functions such as CMS_sign(3) or CMS_encrypt(3) with the CMS_PARTIAL flag set and before the structure is finalised; otherwise the results are undefined. CMS_set1_eContentType() copies the supplied oid, so it should be freed up after use.

CMS_get0_eContentType() returns the type of the embedded content.

CMS_get0_content() returns a pointer to the storage location where the pointer to the embedded content is stored. That means that for example after

ASN1_OCTET_STRING **pconf = CMS_get0_content(cms);

*pconf could be NULL if there is no embedded content. Applications can access, modify or create the embedded content in a CMS_ContentInfo structure using this function. Applications usually will not need to modify the embedded content as it is normally set by higher level functions.

RETURN VALUES

CMS_get0_type() and CMS_get0_eContentType() return internal pointers to OBJECT IDENTIFIER structures.

CMS_get0_content() returns an internal pointer to the storage location where the pointer to the embedded content is stored.

CMS_set1_eContentType() returns 1 for success or 0 if an error occurred. The error can be obtained from ERR_get_error(3).

STANDARDS

RFC 5652: Cryptographic Message Syntax

RFC 3274: Compressed Data Content Type for Cryptographic Message Syntax (CMS)

HISTORY

These functions first appeared in OpenSSL 0.9.8h and have been available since OpenBSD 6.7.