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diff --git a/doc/crypto/PKCS7_sign.pod b/doc/crypto/PKCS7_sign.pod
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+=pod
+
+=head1 NAME
+
+PKCS7_sign - create a PKCS#7 signedData structure
+
+=head1 SYNOPSIS
+
+PKCS7 *PKCS7_sign(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs, BIO *data, int flags);
+
+=head1 DESCRIPTION
+
+PKCS7_sign() creates and returns a PKCS#7 signedData structure. B<signcert>
+is the certificate to sign with, B<pkey> is the corresponsding private key.
+B<certs> is an optional additional set of certificates to include in the
+PKCS#7 structure (for example any intermediate CAs in the chain). 
+
+The data to be signed is read from BIO B<data>.
+
+B<flags> is an optional set of flags.
+
+=head1 NOTES
+
+Any of the following flags (ored together) can be passed in the B<flags> parameter.
+
+Many S/MIME clients expect the signed content to include valid MIME headers. If
+the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are prepended
+to the data.
+
+If B<PKCS7_NOCERTS> is set the signer's certificate will not be included in the
+PKCS7 structure, the signer's certificate must still be supplied in the B<signcert>
+parameter though. This can reduce the size of the signature if the signers certificate
+can be obtained by other means: for example a previously signed message.
+
+The data being signed is included in the PKCS7 structure, unless B<PKCS7_DETACHED> 
+is set in which case it is omitted. This is used for PKCS7 detached signatures
+which are used in S/MIME plaintext signed messages for example.
+
+Normally the supplied content is translated into MIME canonical format (as required
+by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation occurs. This
+option should be used if the supplied data is in binary format otherwise the translation
+will corrupt it.
+
+The signedData structure includes several PKCS#7 autenticatedAttributes including
+the signing time, the PKCS#7 content type and the supported list of ciphers in
+an SMIMECapabilities attribute. If B<PKCS7_NOATTR> is set then no authenticatedAttributes
+will be used. If B<PKCS7_NOSMIMECAP> is set then just the SMIMECapabilities are
+omitted.
+
+=head1 RETURN VALUES
+
+PKCS7_sign() returns either a valid PKCS7 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<PKCS7_verify(3)|PKCS7_verify(3)>
+
+=head1 HISTORY
+
+TBA
+
+=cut