81 lines
2.7 KiB
Text
81 lines
2.7 KiB
Text
=pod
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=head1 NAME
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BIO_f_cipher, BIO_set_cipher, BIO_get_cipher_status, BIO_get_cipher_ctx - cipher BIO filter
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=for comment multiple includes
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=head1 SYNOPSIS
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#include <openssl/bio.h>
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#include <openssl/evp.h>
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const BIO_METHOD *BIO_f_cipher(void);
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void BIO_set_cipher(BIO *b, const EVP_CIPHER *cipher,
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unsigned char *key, unsigned char *iv, int enc);
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int BIO_get_cipher_status(BIO *b)
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int BIO_get_cipher_ctx(BIO *b, EVP_CIPHER_CTX **pctx)
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=head1 DESCRIPTION
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BIO_f_cipher() returns the cipher BIO method. This is a filter
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BIO that encrypts any data written through it, and decrypts any data
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read from it. It is a BIO wrapper for the cipher routines
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EVP_CipherInit(), EVP_CipherUpdate() and EVP_CipherFinal().
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Cipher BIOs do not support BIO_gets() or BIO_puts().
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BIO_flush() on an encryption BIO that is being written through is
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used to signal that no more data is to be encrypted: this is used
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to flush and possibly pad the final block through the BIO.
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BIO_set_cipher() sets the cipher of BIO B<b> to B<cipher> using key B<key>
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and IV B<iv>. B<enc> should be set to 1 for encryption and zero for
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decryption.
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When reading from an encryption BIO the final block is automatically
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decrypted and checked when EOF is detected. BIO_get_cipher_status()
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is a BIO_ctrl() macro which can be called to determine whether the
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decryption operation was successful.
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BIO_get_cipher_ctx() is a BIO_ctrl() macro which retrieves the internal
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BIO cipher context. The retrieved context can be used in conjunction
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with the standard cipher routines to set it up. This is useful when
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BIO_set_cipher() is not flexible enough for the applications needs.
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=head1 NOTES
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When encrypting BIO_flush() B<must> be called to flush the final block
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through the BIO. If it is not then the final block will fail a subsequent
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decrypt.
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When decrypting an error on the final block is signaled by a zero
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return value from the read operation. A successful decrypt followed
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by EOF will also return zero for the final read. BIO_get_cipher_status()
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should be called to determine if the decrypt was successful.
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As always, if BIO_gets() or BIO_puts() support is needed then it can
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be achieved by preceding the cipher BIO with a buffering BIO.
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=head1 RETURN VALUES
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BIO_f_cipher() returns the cipher BIO method.
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BIO_set_cipher() does not return a value.
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BIO_get_cipher_status() returns 1 for a successful decrypt and 0
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for failure.
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BIO_get_cipher_ctx() currently always returns 1.
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=head1 COPYRIGHT
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Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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