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SMIME_write_PKCS7(3)                OpenSSL               SMIME_write_PKCS7(3)

       SMIME_write_PKCS7 - convert PKCS#7 structure to S/MIME format

       libcrypto, -lcrypto

        #include <openssl/pkcs7.h>

        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 streaming is enabled then the content 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

       If the PKCS7_STREAM flag is set streaming is performed. This flag
       should only be set if PKCS7_STREAM was also set in the previous call to
       PKCS7_sign() or PKCS7_encrypt().

       If cleartext signing is being used and PKCS7_STREAM not set then the
       data must be read twice: once to compute the signature in PKCS7_sign()
       and once to output the S/MIME message.

       If streaming is performed the content is output in BER format using
       indefinite length constructed encoding except in the case of signed
       data with detached content where the content is absent and DER format
       is used.

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

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

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

       Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at

1.1.1i                            2018-09-23              SMIME_write_PKCS7(3)