On Wed, Apr 14, 2010, Benjamin Amling wrote:
> Hello,
>
> is it possible to extract the DER blob from the RecipientInfos-part of a
> S/MIME message? I tried the following steps already but couldn't manage
> to get what I want:
>
> *********************************************************************
> BIO *bin = BIO_new(BIO_s_mem());
> BIO_write(bin, mimeMessage.c_str(), mimeMessage.size()); // no errors
>
> CMS_ContentInfo *cms = SMIME_read_CMS(bin, NULL); // no errors
>
> STACK_OF(CMS_RecipientInfo) * ris = CMS_get0_RecipientInfos(cms); // no
> errors
>
> CMS_RecipientInfo *ri;
> for (int i = 0; i < sk_CMS_RecipientInfo_num(ris); ++i) {
> ri = sk_CMS_RecipientInfo_value(ris, i);
> // sk_CMS_RecipientInfo_num(ris) returns 1, so it shouldn't be empty
> // CMS_RecipientInfo_type(ri) returns 0
> }
> **********************************************************************
>
> This is as far as I got. I have no idea on how to proceed and what I can
> do with the CMS_RecipientInfos I managed to extract so far.
>
> I'm still quite new to using the OpenSSL API in C/C++ so I'd appreciate
> any kind of help. :-)
>
>
The return value of CMS_RecipientInfo_type() is a constant indictaing tha type
and will almost always be CMS_RECIPINFO_TRANS (see cms.h). Once you have the
type you can use the appropriate function to retrieve its contents. For example
CMS_RecipientInfo_ktri_get0_signer_id().
Steve.
--
Dr Stephen N. Henson. OpenSSL project core developer.
Commercial tech support now available see: http://www.openssl.org
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