05ea606a25
Fix some code examples, trailing whitespace Fix TBA sections in verify, remove others. Remove empty sections Use Mixed Case not ALL CAPS in head2 Enhance doc-nits script. Remove extra =cut line Reviewed-by: Richard Levitte <levitte@openssl.org>
90 lines
3.2 KiB
Text
90 lines
3.2 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
EVP_SealInit, EVP_SealUpdate, EVP_SealFinal - EVP envelope encryption
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/evp.h>
|
|
|
|
int EVP_SealInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
|
|
unsigned char **ek, int *ekl, unsigned char *iv,
|
|
EVP_PKEY **pubk, int npubk);
|
|
int EVP_SealUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
int *outl, unsigned char *in, int inl);
|
|
int EVP_SealFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
|
|
int *outl);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
The EVP envelope routines are a high level interface to envelope
|
|
encryption. They generate a random key and IV (if required) then
|
|
"envelope" it by using public key encryption. Data can then be
|
|
encrypted using this key.
|
|
|
|
EVP_SealInit() initializes a cipher context B<ctx> for encryption
|
|
with cipher B<type> using a random secret key and IV. B<type> is normally
|
|
supplied by a function such as EVP_aes_256_cbc(). The secret key is encrypted
|
|
using one or more public keys, this allows the same encrypted data to be
|
|
decrypted using any of the corresponding private keys. B<ek> is an array of
|
|
buffers where the public key encrypted secret key will be written, each buffer
|
|
must contain enough room for the corresponding encrypted key: that is
|
|
B<ek[i]> must have room for B<EVP_PKEY_size(pubk[i])> bytes. The actual
|
|
size of each encrypted secret key is written to the array B<ekl>. B<pubk> is
|
|
an array of B<npubk> public keys.
|
|
|
|
The B<iv> parameter is a buffer where the generated IV is written to. It must
|
|
contain enough room for the corresponding cipher's IV, as determined by (for
|
|
example) EVP_CIPHER_iv_length(type).
|
|
|
|
If the cipher does not require an IV then the B<iv> parameter is ignored
|
|
and can be B<NULL>.
|
|
|
|
EVP_SealUpdate() and EVP_SealFinal() have exactly the same properties
|
|
as the EVP_EncryptUpdate() and EVP_EncryptFinal() routines, as
|
|
documented on the L<EVP_EncryptInit(3)> manual
|
|
page.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
EVP_SealInit() returns 0 on error or B<npubk> if successful.
|
|
|
|
EVP_SealUpdate() and EVP_SealFinal() return 1 for success and 0 for
|
|
failure.
|
|
|
|
=head1 NOTES
|
|
|
|
Because a random secret key is generated the random number generator
|
|
must be seeded before calling EVP_SealInit().
|
|
|
|
The public key must be RSA because it is the only OpenSSL public key
|
|
algorithm that supports key transport.
|
|
|
|
Envelope encryption is the usual method of using public key encryption
|
|
on large amounts of data, this is because public key encryption is slow
|
|
but symmetric encryption is fast. So symmetric encryption is used for
|
|
bulk encryption and the small random symmetric key used is transferred
|
|
using public key encryption.
|
|
|
|
It is possible to call EVP_SealInit() twice in the same way as
|
|
EVP_EncryptInit(). The first call should have B<npubk> set to 0
|
|
and (after setting any cipher parameters) it should be called again
|
|
with B<type> set to NULL.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<evp(3)>, L<rand(3)>,
|
|
L<EVP_EncryptInit(3)>,
|
|
L<EVP_OpenInit(3)>
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2016 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
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|