EVP_CIPHER_meth_set_ctrl (3)

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NAME

EVP_CIPHER_meth_new, EVP_CIPHER_meth_dup, EVP_CIPHER_meth_free, EVP_CIPHER_meth_set_iv_length, EVP_CIPHER_meth_set_flags, EVP_CIPHER_meth_set_impl_ctx_size, EVP_CIPHER_meth_set_init, EVP_CIPHER_meth_set_do_cipher, EVP_CIPHER_meth_set_cleanup, EVP_CIPHER_meth_set_set_asn1_params, EVP_CIPHER_meth_set_get_asn1_params, EVP_CIPHER_meth_set_ctrl, EVP_CIPHER_meth_get_init, EVP_CIPHER_meth_get_do_cipher, EVP_CIPHER_meth_get_cleanup, EVP_CIPHER_meth_get_set_asn1_params, EVP_CIPHER_meth_get_get_asn1_params, EVP_CIPHER_meth_get_ctrl - Routines to build up EVP_CIPHER methods

SYNOPSIS

 #include <openssl/evp.h>

 EVP_CIPHER *EVP_CIPHER_meth_new(int cipher_type, int block_size, int key_len);
 EVP_CIPHER *EVP_CIPHER_meth_dup(const EVP_CIPHER *cipher);
 void EVP_CIPHER_meth_free(EVP_CIPHER *cipher);

 int EVP_CIPHER_meth_set_iv_length(EVP_CIPHER *cipher, int iv_len);
 int EVP_CIPHER_meth_set_flags(EVP_CIPHER *cipher, unsigned long flags);
 int EVP_CIPHER_meth_set_impl_ctx_size(EVP_CIPHER *cipher, int ctx_size);
 int EVP_CIPHER_meth_set_init(EVP_CIPHER *cipher,
                              int (*init) (EVP_CIPHER_CTX *ctx,
                                           const unsigned char *key,
                                           const unsigned char *iv,
                                           int enc));
 int EVP_CIPHER_meth_set_do_cipher(EVP_CIPHER *cipher,
                                   int (*do_cipher) (EVP_CIPHER_CTX *ctx,
                                                     unsigned char *out,
                                                     const unsigned char *in,
                                                     size_t inl));
 int EVP_CIPHER_meth_set_cleanup(EVP_CIPHER *cipher,
                                 int (*cleanup) (EVP_CIPHER_CTX *));
 int EVP_CIPHER_meth_set_set_asn1_params(EVP_CIPHER *cipher,
                                         int (*set_asn1_parameters) (EVP_CIPHER_CTX *,
                                                                     ASN1_TYPE *));
 int EVP_CIPHER_meth_set_get_asn1_params(EVP_CIPHER *cipher,
                                         int (*get_asn1_parameters) (EVP_CIPHER_CTX *,
                                                                     ASN1_TYPE *));
 int EVP_CIPHER_meth_set_ctrl(EVP_CIPHER *cipher,
                              int (*ctrl) (EVP_CIPHER_CTX *, int type,
                                           int arg, void *ptr));

 int (*EVP_CIPHER_meth_get_init(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *ctx,
                                                           const unsigned char *key,
                                                           const unsigned char *iv,
                                                           int enc);
 int (*EVP_CIPHER_meth_get_do_cipher(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *ctx,
                                                                unsigned char *out,
                                                                const unsigned char *in,
                                                                size_t inl);
 int (*EVP_CIPHER_meth_get_cleanup(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *);
 int (*EVP_CIPHER_meth_get_set_asn1_params(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
                                                                      ASN1_TYPE *);
 int (*EVP_CIPHER_meth_get_get_asn1_params(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
                                                                ASN1_TYPE *);
 int (*EVP_CIPHER_meth_get_ctrl(const EVP_CIPHER *cipher))(EVP_CIPHER_CTX *,
                                                           int type, int arg,
                                                           void *ptr);

DESCRIPTION

The type is a structure for symmetric cipher method implementation.

EVP_CIPHER_meth_new() creates a new

structure.

EVP_CIPHER_meth_dup() creates a copy of cipher.

EVP_CIPHER_meth_free() destroys a

structure.

EVP_CIPHER_meth_iv_length() sets the length of the

This is only needed when the implemented cipher mode requires it.

EVP_CIPHER_meth_set_flags() sets the flags to describe optional behaviours in the particular cipher. With the exception of cipher modes, of which only one may be present, several flags can be or'd together. The available flags are:

EVP_CIPH_STREAM_CIPHER, EVP_CIPH_ECB_MODE EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE, EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE, EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE

The cipher mode.

EVP_CIPH_VARIABLE_LENGTH

This cipher is of variable length.

EVP_CIPH_CUSTOM_IV

Storing and initialising the

IV

is left entirely to the implementation.

EVP_CIPH_ALWAYS_CALL_INIT

Set this if the implementation's init() function should be called even if key is

NULL

.

EVP_CIPH_CTRL_INIT

Set this to have the implementation's ctrl() function called with command code

EVP_CTRL_INIT

early in its setup.

EVP_CIPH_CUSTOM_KEY_LENGTH

Checking and setting the key length after creating the

EVP_CIPHER

is left to the implementation. Whenever someone uses EVP_CIPHER_CTX_set_key_length() on a

EVP_CIPHER

with this flag set, the implementation's ctrl() function will be called with the control code

EVP_CTRL_SET_KEY_LENGTH

and the key length in arg.

EVP_CIPH_NO_PADDING

Don't use standard block padding.

EVP_CIPH_RAND_KEY

Making a key with random content is left to the implementation. This is done by calling the implementation's ctrl() function with the control code

EVP_CTRL_RAND_KEY

and the pointer to the key memory storage in ptr.

EVP_CIPH_CUSTOM_COPY

Set this to have the implementation's ctrl() function called with command code

EVP_CTRL_COPY

at the end of EVP_CIPHER_CTX_copy(). The intended use is for further things to deal with after the implementation specific data block has been copied. The destination

EVP_CIPHER_CTX

is passed to the control with the ptr parameter. The implementation specific data block is reached with EVP_CIPHER_CTX_get_cipher_data().

EVP_CIPH_FLAG_DEFAULT_ASN1

Use the default

EVP

routines to pass

IV

to and from

ASN.1.

EVP_CIPH_FLAG_LENGTH_BITS

Signals that the length of the input buffer for encryption / decryption is to be understood as the number of bits bits instead of bytes for this implementation. This is only useful for

CFB1

ciphers.

EVP_CIPH_FLAG_CUSTOM_CIPHER

This indicates that the implementation takes care of everything, including padding, buffering and finalization. The

EVP

routines will simply give them control and do nothing more.

EVP_CIPH_FLAG_AEAD_CIPHER

This indicates that this is an

AEAD

cipher implementation.

EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK

Allow interleaving of crypto blocks, a particular optimization only applicable to certain

TLS

ciphers.

EVP_CIPHER_meth_set_impl_ctx_size() sets the size of the

's implementation context so that it can be automatically allocated.

EVP_CIPHER_meth_set_init() sets the cipher init function for cipher. The cipher init function is called by EVP_CipherInit(), EVP_CipherInit_ex(), EVP_EncryptInit(), EVP_EncryptInit_ex(), EVP_DecryptInit(), EVP_DecryptInit_ex().

EVP_CIPHER_meth_set_do_cipher() sets the cipher function for cipher. The cipher function is called by EVP_CipherUpdate(), EVP_EncryptUpdate(), EVP_DecryptUpdate(), EVP_CipherFinal(), EVP_EncryptFinal(), EVP_EncryptFinal_ex(), EVP_DecryptFinal() and EVP_DecryptFinal_ex().

EVP_CIPHER_meth_set_cleanup() sets the function for cipher to do extra cleanup before the method's private data structure is cleaned out and freed. Note that the cleanup function is passed a

*, the private data structure is then available with EVP_CIPHER_CTX_get_cipher_data(). This cleanup function is called by EVP_CIPHER_CTX_reset() and EVP_CIPHER_CTX_free().

EVP_CIPHER_meth_set_ctrl() sets the control function for cipher.

RETURN VALUES

EVP_CIPHER_meth_get_input_blocksize(), EVP_CIPHER_meth_get_result_size(), EVP_CIPHER_meth_get_app_datasize(), EVP_CIPHER_meth_get_flags(), EVP_CIPHER_meth_get_init(), EVP_CIPHER_meth_get_update(), EVP_CIPHER_meth_get_final(), EVP_CIPHER_meth_get_copy(), EVP_CIPHER_meth_get_cleanup() and EVP_CIPHER_meth_get_ctrl() are all used to retrieve the method data given with the EVP_CIPHER_meth_set_*() functions above.

SEE ALSO

EVP_EncryptInit

HISTORY

The structure was openly available in OpenSSL before version 1.1.0. The functions described here were added in OpenSSL 1.1.0.

COPYRIGHT

Copyright 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

in the source distribution or at <www.openssl.org/source/license.html>.