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.\" ========================================================================
.\"
.IX Title "PROVIDER-CIPHER 7"
.TH PROVIDER-CIPHER 7 "2023-05-31" "3.0.9" "OpenSSL"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
provider\-cipher \- The cipher library <\-> provider functions
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& #include <openssl/core_dispatch.h>
\& #include <openssl/core_names.h>
\&
\& /*
\& * None of these are actual functions, but are displayed like this for
\& * the function signatures for functions that are offered as function
\& * pointers in OSSL_DISPATCH arrays.
\& */
\&
\& /* Context management */
\& void *OSSL_FUNC_cipher_newctx(void *provctx);
\& void OSSL_FUNC_cipher_freectx(void *cctx);
\& void *OSSL_FUNC_cipher_dupctx(void *cctx);
\&
\& /* Encryption/decryption */
\& int OSSL_FUNC_cipher_encrypt_init(void *cctx, const unsigned char *key,
\& size_t keylen, const unsigned char *iv,
\& size_t ivlen, const OSSL_PARAM params[]);
\& int OSSL_FUNC_cipher_decrypt_init(void *cctx, const unsigned char *key,
\& size_t keylen, const unsigned char *iv,
\& size_t ivlen, const OSSL_PARAM params[]);
\& int OSSL_FUNC_cipher_update(void *cctx, unsigned char *out, size_t *outl,
\& size_t outsize, const unsigned char *in, size_t inl);
\& int OSSL_FUNC_cipher_final(void *cctx, unsigned char *out, size_t *outl,
\& size_t outsize);
\& int OSSL_FUNC_cipher_cipher(void *cctx, unsigned char *out, size_t *outl,
\& size_t outsize, const unsigned char *in, size_t inl);
\&
\& /* Cipher parameter descriptors */
\& const OSSL_PARAM *OSSL_FUNC_cipher_gettable_params(void *provctx);
\&
\& /* Cipher operation parameter descriptors */
\& const OSSL_PARAM *OSSL_FUNC_cipher_gettable_ctx_params(void *cctx,
\& void *provctx);
\& const OSSL_PARAM *OSSL_FUNC_cipher_settable_ctx_params(void *cctx,
\& void *provctx);
\&
\& /* Cipher parameters */
\& int OSSL_FUNC_cipher_get_params(OSSL_PARAM params[]);
\&
\& /* Cipher operation parameters */
\& int OSSL_FUNC_cipher_get_ctx_params(void *cctx, OSSL_PARAM params[]);
\& int OSSL_FUNC_cipher_set_ctx_params(void *cctx, const OSSL_PARAM params[]);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This documentation is primarily aimed at provider authors. See \fBprovider\fR\|(7)
for further information.
.PP
The \s-1CIPHER\s0 operation enables providers to implement cipher algorithms and make
them available to applications via the \s-1API\s0 functions \fBEVP_EncryptInit_ex\fR\|(3),
\&\fBEVP_EncryptUpdate\fR\|(3) and \fBEVP_EncryptFinal\fR\|(3) (as well as the decrypt
equivalents and other related functions).
.PP
All \*(L"functions\*(R" mentioned here are passed as function pointers between
\&\fIlibcrypto\fR and the provider in \s-1\fBOSSL_DISPATCH\s0\fR\|(3) arrays via
\&\s-1\fBOSSL_ALGORITHM\s0\fR\|(3) arrays that are returned by the provider's
\&\fBprovider_query_operation()\fR function
(see \*(L"Provider Functions\*(R" in \fBprovider\-base\fR\|(7)).
.PP
All these \*(L"functions\*(R" have a corresponding function type definition
named \fBOSSL_FUNC_{name}_fn\fR, and a helper function to retrieve the
function pointer from an \s-1\fBOSSL_DISPATCH\s0\fR\|(3) element named
\&\fBOSSL_FUNC_{name}\fR.
For example, the \*(L"function\*(R" \fBOSSL_FUNC_cipher_newctx()\fR has these:
.PP
.Vb 3
\& typedef void *(OSSL_FUNC_cipher_newctx_fn)(void *provctx);
\& static ossl_inline OSSL_FUNC_cipher_newctx_fn
\& OSSL_FUNC_cipher_newctx(const OSSL_DISPATCH *opf);
.Ve
.PP
\&\s-1\fBOSSL_DISPATCH\s0\fR\|(3) arrays are indexed by numbers that are provided as
macros in \fBopenssl\-core_dispatch.h\fR\|(7), as follows:
.PP
.Vb 3
\& OSSL_FUNC_cipher_newctx OSSL_FUNC_CIPHER_NEWCTX
\& OSSL_FUNC_cipher_freectx OSSL_FUNC_CIPHER_FREECTX
\& OSSL_FUNC_cipher_dupctx OSSL_FUNC_CIPHER_DUPCTX
\&
\& OSSL_FUNC_cipher_encrypt_init OSSL_FUNC_CIPHER_ENCRYPT_INIT
\& OSSL_FUNC_cipher_decrypt_init OSSL_FUNC_CIPHER_DECRYPT_INIT
\& OSSL_FUNC_cipher_update OSSL_FUNC_CIPHER_UPDATE
\& OSSL_FUNC_cipher_final OSSL_FUNC_CIPHER_FINAL
\& OSSL_FUNC_cipher_cipher OSSL_FUNC_CIPHER_CIPHER
\&
\& OSSL_FUNC_cipher_get_params OSSL_FUNC_CIPHER_GET_PARAMS
\& OSSL_FUNC_cipher_get_ctx_params OSSL_FUNC_CIPHER_GET_CTX_PARAMS
\& OSSL_FUNC_cipher_set_ctx_params OSSL_FUNC_CIPHER_SET_CTX_PARAMS
\&
\& OSSL_FUNC_cipher_gettable_params OSSL_FUNC_CIPHER_GETTABLE_PARAMS
\& OSSL_FUNC_cipher_gettable_ctx_params OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS
\& OSSL_FUNC_cipher_settable_ctx_params OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS
.Ve
.PP
A cipher algorithm implementation may not implement all of these functions.
In order to be a consistent set of functions there must at least be a complete
set of \*(L"encrypt\*(R" functions, or a complete set of \*(L"decrypt\*(R" functions, or a
single \*(L"cipher\*(R" function.
In all cases both the OSSL_FUNC_cipher_newctx and OSSL_FUNC_cipher_freectx functions must be
present.
All other functions are optional.
.SS "Context Management Functions"
.IX Subsection "Context Management Functions"
\&\fBOSSL_FUNC_cipher_newctx()\fR should create and return a pointer to a provider side
structure for holding context information during a cipher operation.
A pointer to this context will be passed back in a number of the other cipher
operation function calls.
The parameter \fIprovctx\fR is the provider context generated during provider
initialisation (see \fBprovider\fR\|(7)).
.PP
\&\fBOSSL_FUNC_cipher_freectx()\fR is passed a pointer to the provider side cipher context in
the \fIcctx\fR parameter.
This function should free any resources associated with that context.
.PP
\&\fBOSSL_FUNC_cipher_dupctx()\fR should duplicate the provider side cipher context in the
\&\fIcctx\fR parameter and return the duplicate copy.
.SS "Encryption/Decryption Functions"
.IX Subsection "Encryption/Decryption Functions"
\&\fBOSSL_FUNC_cipher_encrypt_init()\fR initialises a cipher operation for encryption given a
newly created provider side cipher context in the \fIcctx\fR parameter.
The key to be used is given in \fIkey\fR which is \fIkeylen\fR bytes long.
The \s-1IV\s0 to be used is given in \fIiv\fR which is \fIivlen\fR bytes long.
The \fIparams\fR, if not \s-1NULL,\s0 should be set on the context in a manner similar to
using \fBOSSL_FUNC_cipher_set_ctx_params()\fR.
.PP
\&\fBOSSL_FUNC_cipher_decrypt_init()\fR is the same as \fBOSSL_FUNC_cipher_encrypt_init()\fR except that it
initialises the context for a decryption operation.
.PP
\&\fBOSSL_FUNC_cipher_update()\fR is called to supply data to be encrypted/decrypted as part of
a previously initialised cipher operation.
The \fIcctx\fR parameter contains a pointer to a previously initialised provider
side context.
\&\fBOSSL_FUNC_cipher_update()\fR should encrypt/decrypt \fIinl\fR bytes of data at the location
pointed to by \fIin\fR.
The encrypted data should be stored in \fIout\fR and the amount of data written to
\&\fI*outl\fR which should not exceed \fIoutsize\fR bytes.
\&\fBOSSL_FUNC_cipher_update()\fR may be called multiple times for a single cipher operation.
It is the responsibility of the cipher implementation to handle input lengths
that are not multiples of the block length.
In such cases a cipher implementation will typically cache partial blocks of
input data until a complete block is obtained.
\&\fIout\fR may be the same location as \fIin\fR but it should not partially overlap.
The same expectations apply to \fIoutsize\fR as documented for
\&\fBEVP_EncryptUpdate\fR\|(3) and \fBEVP_DecryptUpdate\fR\|(3).
.PP
\&\fBOSSL_FUNC_cipher_final()\fR completes an encryption or decryption started through previous
\&\fBOSSL_FUNC_cipher_encrypt_init()\fR or \fBOSSL_FUNC_cipher_decrypt_init()\fR, and \fBOSSL_FUNC_cipher_update()\fR
calls.
The \fIcctx\fR parameter contains a pointer to the provider side context.
Any final encryption/decryption output should be written to \fIout\fR and the
amount of data written to \fI*outl\fR which should not exceed \fIoutsize\fR bytes.
The same expectations apply to \fIoutsize\fR as documented for
\&\fBEVP_EncryptFinal\fR\|(3) and \fBEVP_DecryptFinal\fR\|(3).
.PP
\&\fBOSSL_FUNC_cipher_cipher()\fR performs encryption/decryption using the provider side cipher
context in the \fIcctx\fR parameter that should have been previously initialised via
a call to \fBOSSL_FUNC_cipher_encrypt_init()\fR or \fBOSSL_FUNC_cipher_decrypt_init()\fR.
This should call the raw underlying cipher function without any padding.
This will be invoked in the provider as a result of the application calling
\&\fBEVP_Cipher\fR\|(3).
The application is responsible for ensuring that the input is a multiple of the
block length.
The data to be encrypted/decrypted will be in \fIin\fR, and it will be \fIinl\fR bytes
in length.
The output from the encryption/decryption should be stored in \fIout\fR and the
amount of data stored should be put in \fI*outl\fR which should be no more than
\&\fIoutsize\fR bytes.
.SS "Cipher Parameters"
.IX Subsection "Cipher Parameters"
See \s-1\fBOSSL_PARAM\s0\fR\|(3) for further details on the parameters structure used by
these functions.
.PP
\&\fBOSSL_FUNC_cipher_get_params()\fR gets details of the algorithm implementation
and stores them in \fIparams\fR.
.PP
\&\fBOSSL_FUNC_cipher_set_ctx_params()\fR sets cipher operation parameters for the
provider side cipher context \fIcctx\fR to \fIparams\fR.
Any parameter settings are additional to any that were previously set.
Passing \s-1NULL\s0 for \fIparams\fR should return true.
.PP
\&\fBOSSL_FUNC_cipher_get_ctx_params()\fR gets cipher operation details details from
the given provider side cipher context \fIcctx\fR and stores them in \fIparams\fR.
Passing \s-1NULL\s0 for \fIparams\fR should return true.
.PP
\&\fBOSSL_FUNC_cipher_gettable_params()\fR, \fBOSSL_FUNC_cipher_gettable_ctx_params()\fR,
and \fBOSSL_FUNC_cipher_settable_ctx_params()\fR all return constant \s-1\fBOSSL_PARAM\s0\fR\|(3)
arrays as descriptors of the parameters that \fBOSSL_FUNC_cipher_get_params()\fR,
\&\fBOSSL_FUNC_cipher_get_ctx_params()\fR, and \fBOSSL_FUNC_cipher_set_ctx_params()\fR
can handle, respectively. \fBOSSL_FUNC_cipher_gettable_ctx_params()\fR and
\&\fBOSSL_FUNC_cipher_settable_ctx_params()\fR will return the parameters associated
with the provider side context \fIcctx\fR in its current state if it is
not \s-1NULL.\s0 Otherwise, they return the parameters associated with the
provider side algorithm \fIprovctx\fR.
.PP
Parameters currently recognised by built-in ciphers are listed in
\&\*(L"\s-1PARAMETERS\*(R"\s0 in \fBEVP_EncryptInit\fR\|(3).
Not all parameters are relevant to, or are understood by all ciphers.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBOSSL_FUNC_cipher_newctx()\fR and \fBOSSL_FUNC_cipher_dupctx()\fR should return the newly created
provider side cipher context, or \s-1NULL\s0 on failure.
.PP
\&\fBOSSL_FUNC_cipher_encrypt_init()\fR, \fBOSSL_FUNC_cipher_decrypt_init()\fR, \fBOSSL_FUNC_cipher_update()\fR,
\&\fBOSSL_FUNC_cipher_final()\fR, \fBOSSL_FUNC_cipher_cipher()\fR, \fBOSSL_FUNC_cipher_get_params()\fR,
\&\fBOSSL_FUNC_cipher_get_ctx_params()\fR and \fBOSSL_FUNC_cipher_set_ctx_params()\fR should return 1 for
success or 0 on error.
.PP
\&\fBOSSL_FUNC_cipher_gettable_params()\fR, \fBOSSL_FUNC_cipher_gettable_ctx_params()\fR and
\&\fBOSSL_FUNC_cipher_settable_ctx_params()\fR should return a constant \s-1\fBOSSL_PARAM\s0\fR\|(3)
array, or \s-1NULL\s0 if none is offered.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBprovider\fR\|(7), \s-1\fBOSSL_PROVIDER\-FIPS\s0\fR\|(7), \fBOSSL_PROVIDER\-default\fR\|(7),
\&\fBOSSL_PROVIDER\-legacy\fR\|(7),
\&\s-1\fBEVP_CIPHER\-AES\s0\fR\|(7), \s-1\fBEVP_CIPHER\-ARIA\s0\fR\|(7), \s-1\fBEVP_CIPHER\-BLOWFISH\s0\fR\|(7),
\&\s-1\fBEVP_CIPHER\-CAMELLIA\s0\fR\|(7), \s-1\fBEVP_CIPHER\-CAST\s0\fR\|(7), \s-1\fBEVP_CIPHER\-CHACHA\s0\fR\|(7),
\&\s-1\fBEVP_CIPHER\-DES\s0\fR\|(7), \s-1\fBEVP_CIPHER\-IDEA\s0\fR\|(7), \s-1\fBEVP_CIPHER\-RC2\s0\fR\|(7),
\&\s-1\fBEVP_CIPHER\-RC4\s0\fR\|(7), \s-1\fBEVP_CIPHER\-RC5\s0\fR\|(7), \s-1\fBEVP_CIPHER\-SEED\s0\fR\|(7),
\&\s-1\fBEVP_CIPHER\-SM4\s0\fR\|(7), \s-1\fBEVP_CIPHER\-NULL\s0\fR\|(7),
\&\fBlife_cycle\-cipher\fR\|(7), \fBEVP_EncryptInit\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
The provider \s-1CIPHER\s0 interface was introduced in OpenSSL 3.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2019\-2023 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.