| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | PKCS7_encrypt_ex, PKCS7_encrypt
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| 6 | - create a PKCS#7 envelopedData structure
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| 7 |
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| 8 | =head1 SYNOPSIS
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| 9 |
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| 10 | #include <openssl/pkcs7.h>
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| 11 |
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| 12 | PKCS7 *PKCS7_encrypt_ex(STACK_OF(X509) *certs, BIO *in,
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| 13 | const EVP_CIPHER *cipher, int flags,
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| 14 | OSSL_LIB_CTX *libctx, const char *propq);
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| 15 | PKCS7 *PKCS7_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher,
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| 16 | int flags);
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| 17 |
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| 18 | =head1 DESCRIPTION
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| 19 |
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| 20 | PKCS7_encrypt_ex() creates and returns a PKCS#7 envelopedData structure.
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| 21 | I<certs> is a list of recipient certificates. I<in> is the content to be
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| 22 | encrypted. I<cipher> is the symmetric cipher to use. I<flags> is an optional set
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| 23 | of flags. The library context I<libctx> and the property query I<propq> are used
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| 24 | when retrieving algorithms from providers.
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| 25 |
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| 26 | Only RSA keys are supported in PKCS#7 and envelopedData so the recipient
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| 27 | certificates supplied to this function must all contain RSA public keys, though
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| 28 | they do not have to be signed using the RSA algorithm.
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| 29 |
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| 30 | EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use
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| 31 | because most clients will support it.
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| 32 |
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| 33 | Some old "export grade" clients may only support weak encryption using 40 or 64
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| 34 | bit RC2. These can be used by passing EVP_rc2_40_cbc() and EVP_rc2_64_cbc()
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| 35 | respectively.
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| 36 |
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| 37 | The algorithm passed in the B<cipher> parameter must support ASN1 encoding of
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| 38 | its parameters.
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| 39 |
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| 40 | Many browsers implement a "sign and encrypt" option which is simply an S/MIME
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| 41 | envelopedData containing an S/MIME signed message. This can be readily produced
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| 42 | by storing the S/MIME signed message in a memory BIO and passing it to
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| 43 | PKCS7_encrypt().
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| 44 |
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| 45 | The following flags can be passed in the B<flags> parameter.
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| 46 |
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| 47 | If the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are
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| 48 | prepended to the data.
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| 49 |
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| 50 | Normally the supplied content is translated into MIME canonical format (as
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| 51 | required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation
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| 52 | occurs. This option should be used if the supplied data is in binary format
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| 53 | otherwise the translation will corrupt it. If B<PKCS7_BINARY> is set then
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| 54 | B<PKCS7_TEXT> is ignored.
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| 55 |
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| 56 | If the B<PKCS7_STREAM> flag is set a partial B<PKCS7> structure is output
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| 57 | suitable for streaming I/O: no data is read from the BIO B<in>.
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| 58 |
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| 59 | If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not>
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| 60 | complete and outputting its contents via a function that does not
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| 61 | properly finalize the B<PKCS7> structure will give unpredictable
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| 62 | results.
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| 63 |
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| 64 | Several functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(),
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| 65 | PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization
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| 66 | can be performed by obtaining the streaming ASN1 B<BIO> directly using
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| 67 | BIO_new_PKCS7().
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| 68 |
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| 69 | PKCS7_encrypt() is similar to PKCS7_encrypt_ex() but uses default
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| 70 | values of NULL for the library context I<libctx> and the property query I<propq>.
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| 71 |
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| 72 | =head1 RETURN VALUES
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| 73 |
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| 74 | PKCS7_encrypt_ex() and PKCS7_encrypt() return either a PKCS7 structure
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| 75 | or NULL if an error occurred. The error can be obtained from ERR_get_error(3).
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| 76 |
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| 77 | =head1 SEE ALSO
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| 78 |
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| 79 | L<ERR_get_error(3)>, L<PKCS7_decrypt(3)>
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| 80 |
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| 81 | =head1 HISTORY
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| 82 |
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| 83 | The function PKCS7_encrypt_ex() was added in OpenSSL 3.0.
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| 84 |
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| 85 | The B<PKCS7_STREAM> flag was added in OpenSSL 1.0.0.
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| 86 |
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| 87 | =head1 COPYRIGHT
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| 88 |
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| 89 | Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.
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| 90 |
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| 91 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 92 | this file except in compliance with the License. You can obtain a copy
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| 93 | in the file LICENSE in the source distribution or at
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| 94 | L<https://www.openssl.org/source/license.html>.
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| 95 |
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| 96 | =cut
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