HP Open Source Security for OpenVMS Volume 2: HP SSL for OpenVMS > CRYPTO Application Programming Interface (API) Reference


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SMIME_write_PKCS7 — convert PKCS#7 structure to S/MIME format.


int SMIME_write_PKCS7(BIO *out, PKCS7 *p7,
BIO *data, int flags);


SMIME_write_PKCS7() adds the appropriate MIME headers to a PKCS#7 structure to produce an S/MIME message.

out is the BIO to write the data to. p7 is the appropriate PKCS7 structure. If cleartext signing (multipart/signed) is being used then the signed data must be supplied in the data argument. flags is an optional set of flags.


The following flags can be passed in the flags parameter.

If PKCS7_DETACHED is set then cleartext signing will be used, this option only makes sense for signedData where PKCS7_DETACHED is also set when PKCS7_sign() is also called.

If the PKCS7_TEXT flag is set MIME headers for type text/plain are added to the content, this only makes sense if PKCS7_DETACHED is also set.

If cleartext signing is being used then the data must be read twice: once to compute the signature in PKCS7_sign() and once to output the S/MIME message.


SMIME_write_PKCS7() always base64 encodes PKCS#7 structures, there should be an option to disable this.

There should really be a way to produce cleartext signing using only a single pass of the data.


SMIME_write_PKCS7() returns 1 for success or 0 for failure.


ERR_get_error(3), PKCS7_sign(3), PKCS7_verify(3), PKCS7_encrypt(3) PKCS7_decrypt(3)


SMIME_write_PKCS7() was added to OpenSSL 0.9.5