- NAME
- SYNOPSIS
- DESCRIPTION
- NOTES
- RETURN VALUES
- SEE ALSO
- HISTORY

# NAME

     CMS_get0_SignerInfos, CMS_SignerInfo_get0_signer_id, CMS_SignerInfo_cert_cmp, CMS_set1_signer_certs - CMS signedData signer functions.

# SYNOPSIS

     #include <openssl/cms.h>

     STACK_OF(CMS_SignerInfo) *CMS_get0_SignerInfos(CMS_ContentInfo *cms);

     int CMS_SignerInfo_get0_signer_id(CMS_SignerInfo *si, ASN1_OCTET_STRING **keyid, X509_NAME **issuer, ASN1_INTEGER **sno);
     int CMS_SignerInfo_cert_cmp(CMS_SignerInfo *si, X509 *cert);
     void CMS_SignerInfo_set1_signer_cert(CMS_SignerInfo *si, X509 *signer);

# DESCRIPTION

The function `CMS_get0_SignerInfos()` returns all the CMS_SignerInfo structures associated with a CMS signedData structure.

`CMS_SignerInfo_get0_signer_id()` retrieves the certificate signer identifier associated with a specific CMS_SignerInfo structure si. Either the keyidentifier will be set in keyid or both issuer name and serial number in issuer and sno.

`CMS_SignerInfo_cert_cmp()` compares the certificate cert against the signer identifier si. It returns zero if the comparison is successful and non zero if not.

`CMS_SignerInfo_set1_signer_cert()` sets the signers certificate of si to signer.

# NOTES

The main purpose of these functions is to enable an application to lookup signers certificates using any appropriate technique when the simpler method of `CMS_verify()` is not appropriate.

In typical usage and application will retrieve all CMS_SignerInfo structures using `CMS_get0_SignerInfo()` and retrieve the identifier information using CMS. It will then obtain the signer certificate by some unspecified means (or return and error if it cannot be found) and set it using CMS_SignerInfo_set1_signer_cert().

Once all signer certificates have been set `CMS_verify()` can be used.

Although `CMS_get0_SignerInfos()` can return NULL is an error occur or if there are no signers this is not a problem in practice because the only error which can occur is if the cms structure is not of type signedData due to application error.

# RETURN VALUES

`CMS_get0_SignerInfos()` returns all CMS_SignerInfo structures, or NULL there are no signers or an error occurs.

`CMS_SignerInfo_get0_signer_id()` returns 1 for success and 0 for failure.

`CMS_SignerInfo_cert_cmp()` returns 0 for a successful comparison and non zero otherwise.

`CMS_SignerInfo_set1_signer_cert()` does not return a value.

Any error can be obtained from ERR_get_error

# SEE ALSO

ERR_get_error, CMS_verify

# HISTORY

These functions were first was added to OpenSSL 0.9.8