| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | SMIME_read_CMS_ex, SMIME_read_CMS - parse S/MIME message
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| 6 |
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| 7 | =head1 SYNOPSIS
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| 8 |
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| 9 | #include <openssl/cms.h>
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| 10 |
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| 11 | CMS_ContentInfo *SMIME_read_CMS_ex(BIO *bio, int flags, BIO **bcont,
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| 12 | CMS_ContentInfo **cms);
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| 13 | CMS_ContentInfo *SMIME_read_CMS(BIO *in, BIO **bcont);
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| 14 |
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| 15 | =head1 DESCRIPTION
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| 16 |
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| 17 | SMIME_read_CMS() parses a message in S/MIME format.
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| 18 |
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| 19 | B<in> is a BIO to read the message from.
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| 20 |
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| 21 | If cleartext signing is used then the content is saved in a memory bio which is
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| 22 | written to B<*bcont>, otherwise B<*bcont> is set to NULL.
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| 23 |
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| 24 | The parsed CMS_ContentInfo structure is returned or NULL if an
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| 25 | error occurred.
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| 26 |
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| 27 | SMIME_read_CMS_ex() is similar to SMIME_read_CMS() but optionally a previously
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| 28 | created I<cms> CMS_ContentInfo object can be supplied as well as some I<flags>.
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| 29 | To create a I<cms> object use L<CMS_ContentInfo_new_ex(3)>.
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| 30 | If the I<flags> argument contains B<CMS_BINARY> then the input is assumed to be
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| 31 | in binary format and is not translated to canonical form.
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| 32 | If in addition B<SMIME_ASCIICRLF> is set then the binary input is assumed
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| 33 | to be followed by B<CR> and B<LF> characters, else only by an B<LF> character.
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| 34 | If I<flags> is 0 and I<cms> is NULL then it is identical to SMIME_read_CMS().
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| 35 |
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| 36 | =head1 NOTES
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| 37 |
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| 38 | If B<*bcont> is not NULL then the message is clear text signed. B<*bcont> can
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| 39 | then be passed to CMS_verify() with the B<CMS_DETACHED> flag set.
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| 40 |
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| 41 | Otherwise the type of the returned structure can be determined
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| 42 | using CMS_get0_type().
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| 43 |
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| 44 | To support future functionality if B<bcont> is not NULL B<*bcont> should be
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| 45 | initialized to NULL. For example:
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| 46 |
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| 47 | BIO *cont = NULL;
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| 48 | CMS_ContentInfo *cms;
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| 49 |
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| 50 | cms = SMIME_read_CMS(in, &cont);
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| 51 |
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| 52 | =head1 BUGS
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| 53 |
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| 54 | The MIME parser used by SMIME_read_CMS() is somewhat primitive. While it will
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| 55 | handle most S/MIME messages more complex compound formats may not work.
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| 56 |
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| 57 | The parser assumes that the CMS_ContentInfo structure is always base64 encoded
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| 58 | and will not handle the case where it is in binary format or uses quoted
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| 59 | printable format.
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| 60 |
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| 61 | The use of a memory BIO to hold the signed content limits the size of message
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| 62 | which can be processed due to memory restraints: a streaming single pass option
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| 63 | should be available.
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| 64 |
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| 65 | =head1 RETURN VALUES
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| 66 |
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| 67 | SMIME_read_CMS_ex() and SMIME_read_CMS() return a valid B<CMS_ContentInfo>
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| 68 | structure or B<NULL> if an error occurred. The error can be obtained from
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| 69 | ERR_get_error(3).
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| 70 |
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| 71 | =head1 SEE ALSO
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| 72 |
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| 73 | L<ERR_get_error(3)>,
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| 74 | L<CMS_sign(3)>,
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| 75 | L<CMS_verify(3)>,
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| 76 | L<CMS_encrypt(3)>,
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| 77 | L<CMS_decrypt(3)>
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| 78 |
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| 79 | =head1 HISTORY
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| 80 |
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| 81 | The function SMIME_read_CMS_ex() was added in OpenSSL 3.0.
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| 82 |
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| 83 | =head1 COPYRIGHT
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| 84 |
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| 85 | Copyright 2008-2021 The OpenSSL Project Authors. All Rights Reserved.
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| 86 |
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| 87 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 88 | this file except in compliance with the License. You can obtain a copy
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| 89 | in the file LICENSE in the source distribution or at
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| 90 | L<https://www.openssl.org/source/license.html>.
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| 91 |
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| 92 | =cut
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