Add CMS signed receipt genration and verification docs.

doc/crypto/CMS_sign_receipt.pod

+=pod
+
+=head1 NAME
+
+CMS_sign_receipt - create a CMS signed receipt
+
+=head1 SYNOPSIS
+
+ #include <openssl/cms.h>
+
+ CMS_ContentInfo *CMS_sign_receipt(CMS_SignerInfo *si, X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs, unsigned int flags);
+
+=head1 DESCRIPTION
+
+CMS_sign_receipt() creates and returns a CMS signed receipt structure. B<si> is
+the B<CMS_SignerInfo> structure containing the signed receipt request.
+B<signcert> is the certificate to sign with, B<pkey> is the corresponding
+private key.  B<certs> is an optional additional set of certificates to include
+in the CMS structure (for example any intermediate CAs in the chain).
+
+B<flags> is an optional set of flags.
+
+=head1 NOTES
+
+This functions behaves in a similar way to CMS_sign() except the flag values
+B<CMS_DETACHED>, B<CMS_BINARY>, B<CMS_NOATTR>, B<CMS_TEXT> and B<CMS_STREAM>
+are not supported since they do not make sense in the context of signed
+receipts.
+
+=head1 RETURN VALUES
+
+CMS_sign_receipt() returns either a valid CMS_ContentInfo structure or NULL if
+an error occurred.  The error can be obtained from ERR_get_error(3).
+
+=head1 SEE ALSO
+
+L<ERR_get_error(3)|ERR_get_error(3)>,
+L<CMS_verify_receipt(3)|CMS_verify_receipt(3)>,
+L<CMS_sign(3)|CMS_sign(3)>
+
+=head1 HISTORY
+
+CMS_sign_receipt() was added to OpenSSL 0.9.8
+
+=cut

doc/crypto/CMS_verify_receipt.pod

+=pod
+
+=head1 NAME
+
+CMS_verify - verify a CMS signed receipt
+
+=head1 SYNOPSIS
+
+ #include <openssl/cms.h>
+
+ int CMS_verify_receipt(CMS_ContentInfo *rcms, CMS_ContentInfo *ocms, STACK_OF(X509) *certs, X509_STORE *store, unsigned int flags);
+
+=head1 DESCRIPTION
+
+CMS_verify_receipt() verifies a CMS signed receipt. B<rcms> is the signed
+receipt to verify. B<ocms> is the original SignedData structure containing the
+receipt request B<certs> is a set of certificates in which to search for the
+signer's certificate. B<store> is a trusted certificate store (used for chain
+verification). 
+
+B<flags> is an optional set of flags, which can be used to modify the verify
+operation.
+
+=head1 NOTES
+
+This functions behaves in a similar way to CMS_verify() except the flag values
+B<CMS_DETACHED>, B<CMS_BINARY>, B<CMS_TEXT> and B<CMS_STREAM> are not
+supported since they do not make sense in the context of signed receipts.
+
+=head1 RETURN VALUES
+
+CMS_verify_receipt() returns 1 for a successful verification and zero if an
+error occurred.
+
+The error can be obtained from L<ERR_get_error(3)|ERR_get_error(3)>
+
+=head1 SEE ALSO
+
+L<ERR_get_error(3)|ERR_get_error(3)>,
+L<CMS_sign_receipt(3)|CMS_sign_receipt(3)>,
+L<CMS_verify(3)|CMS_verify(3)>,
+
+=head1 HISTORY
+
+CMS_verify() was added to OpenSSL 0.9.8
+
+=cut