provider-cipher - The cipher library <-> provider functions
#include <openssl/core_numbers.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 *OP_cipher_newctx(void *provctx); void OP_cipher_freectx(void *cctx); void *OP_cipher_dupctx(void *cctx);
/* Encryption/decryption */
int OP_cipher_encrypt_init(void *cctx, const unsigned char *key,
size_t keylen, const unsigned char *iv,
size_t ivlen);
int OP_cipher_decrypt_init(void *cctx, const unsigned char *key,
size_t keylen, const unsigned char *iv,
size_t ivlen);
int OP_cipher_update(void *cctx, unsigned char *out, size_t *outl,
size_t outsize, const unsigned char *in, size_t inl);
int OP_cipher_final(void *cctx, unsigned char *out, size_t *outl,
size_t outsize);
int OP_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 *OP_cipher_gettable_params(void);
/* Cipher operation parameter descriptors */ const OSSL_PARAM *OP_cipher_gettable_ctx_params(void); const OSSL_PARAM *OP_cipher_settable_ctx_params(void);
/* Cipher parameters */ int OP_cipher_get_params(OSSL_PARAM params[]);
/* Cipher operation parameters */ int OP_cipher_get_ctx_params(void *cctx, OSSL_PARAM params[]); int OP_cipher_set_ctx_params(void *cctx, const OSSL_PARAM params[]);
This documentation is primarily aimed at provider authors. See provider(7) for further information.
The CIPHER operation enables providers to implement cipher algorithms and make them available to applications via the API functions EVP_EncryptInit_ex(3), EVP_EncryptUpdate(3) and EVP_EncryptFinal(3) (as well as the decrypt equivalents and other related functions).
All "functions" mentioned here are passed as function pointers between
libcrypto and the provider in OSSL_DISPATCH arrays via
OSSL_ALGORITHM arrays that are returned by the provider's
provider_query_operation() function
(see provider-base(7)/Provider Functions).
All these "functions" have a corresponding function type definition
named OSSL_{name}_fn, and a helper function to retrieve the
function pointer from an OSSL_DISPATCH element named
OSSL_get_{name}.
For example, the "function" OP_cipher_newctx() has these:
typedef void *(OSSL_OP_cipher_newctx_fn)(void *provctx);
static ossl_inline OSSL_OP_cipher_newctx_fn
OSSL_get_OP_cipher_newctx(const OSSL_DISPATCH *opf);
OSSL_DISPATCH arrays are indexed by numbers that are provided as macros in openssl-core_numbers.h(7), as follows:
OP_cipher_newctx OSSL_FUNC_CIPHER_NEWCTX OP_cipher_freectx OSSL_FUNC_CIPHER_FREECTX OP_cipher_dupctx OSSL_FUNC_CIPHER_DUPCTX
OP_cipher_encrypt_init OSSL_FUNC_CIPHER_ENCRYPT_INIT OP_cipher_decrypt_init OSSL_FUNC_CIPHER_DECRYPT_INIT OP_cipher_update OSSL_FUNC_CIPHER_UPDATE OP_cipher_final OSSL_FUNC_CIPHER_FINAL OP_cipher_cipher OSSL_FUNC_CIPHER_CIPHER
OP_cipher_get_params OSSL_FUNC_CIPHER_GET_PARAMS OP_cipher_get_ctx_params OSSL_FUNC_CIPHER_GET_CTX_PARAMS OP_cipher_set_ctx_params OSSL_FUNC_CIPHER_SET_CTX_PARAMS
OP_cipher_gettable_params OSSL_FUNC_CIPHER_GETTABLE_PARAMS OP_cipher_gettable_ctx_params OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS OP_cipher_settable_ctx_params OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS
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 "encrypt" functions, or a complete set of "decrypt" functions, or a single "cipher" function. In all cases both the OP_cipher_newctx and OP_cipher_freectx functions must be present. All other functions are optional.
OP_cipher_newctx() 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 provctx is the provider context generated during provider
initialisation (see provider(7)).
OP_cipher_freectx() is passed a pointer to the provider side cipher context in
the cctx parameter.
This function should free any resources associated with that context.
OP_cipher_dupctx() should duplicate the provider side cipher context in the
cctx parameter and return the duplicate copy.
OP_cipher_encrypt_init() initialises a cipher operation for encryption given a
newly created provider side cipher context in the cctx parameter.
The key to be used is given in key which is keylen bytes long.
The IV to be used is given in iv which is ivlen bytes long.
OP_cipher_decrypt_init() is the same as OP_cipher_encrypt_init() except that it
initialises the context for a decryption operation.
OP_cipher_update() is called to supply data to be encrypted/decrypted as part of
a previously initialised cipher operation.
The cctx parameter contains a pointer to a previously initialised provider
side context.
OP_cipher_update() should encrypt/decrypt inl bytes of data at the location
pointed to by in.
The encrypted data should be stored in out and the amount of data written to
*outl which should not exceed outsize bytes.
OP_cipher_update() 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.
out may be the same location as in but it should not partially overlap.
The same expectations apply to outsize as documented for
EVP_EncryptUpdate(3) and EVP_DecryptUpdate(3).
OP_cipher_final() completes an encryption or decryption started through previous
OP_cipher_encrypt_init() or OP_cipher_decrypt_init(), and OP_cipher_update()
calls.
The cctx parameter contains a pointer to the provider side context.
Any final encryption/decryption output should be written to out and the
amount of data written to *outl which should not exceed outsize bytes.
The same expectations apply to outsize as documented for
EVP_EncryptFinal(3) and EVP_DecryptFinal(3).
OP_cipher_cipher() performs encryption/decryption using the provider side cipher
context in the cctx parameter that should have been previously initialised via
a call to OP_cipher_encrypt_init() or OP_cipher_decrypt_init().
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
EVP_Cipher(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 in, and it will be inl bytes
in length.
The output from the encryption/decryption should be stored in out and the
amount of data stored should be put in *outl which should be no more than
outsize bytes.
See OSSL_PARAM(3) for further details on the parameters structure used by these functions.
OP_cipher_get_params() gets details of the algorithm implementation
and stores them in params.
OP_cipher_set_ctx_params() sets cipher operation parameters for the
provider side cipher context cctx to params.
Any parameter settings are additional to any that were previously set.
OP_cipher_get_ctx_params() gets cipher operation details details from
the given provider side cipher context cctx and stores them in params.
OP_cipher_gettable_params(), OP_cipher_gettable_ctx_params(), and
OP_cipher_settable_ctx_params() all return constant OSSL_PARAM arrays
as descriptors of the parameters that OP_cipher_get_params(),
OP_cipher_get_ctx_params(), and OP_cipher_set_ctx_params() can handle,
respectively.
Parameters currently recognised by built-in ciphers are as follows. Not all parameters are relevant to, or are understood by all ciphers:
Sets the padding mode for the associated cipher ctx. Setting a value of 1 will turn padding on. Setting a value of 0 will turn padding off.
Gets the mode for the associated cipher algorithm. See EVP_CIPHER_mode(3) for a list of valid modes.
Gets the block size for the associated cipher algorithm. The block size should be 1 for stream ciphers. Note that the block size for a cipher may be different to the block size for the underlying encryption/decryption primitive. For example AES in CTR mode has a block size of 1 (because it operates like a stream cipher), even though AES has a block size of 16. The length of the "blocksize" parameter should not exceed that of a size_t.
Gets any flags for the associated cipher algorithm. See EVP_CIPHER_meth_set_flags(3) for a list of currently defined cipher flags. The length of the "flags" parameter should equal that of an unsigned long int.
Gets the key length for the associated cipher algorithm. This can also be used to get or set the key length for the associated cipher ctx. The length of the "keylen" parameter should not exceed that of a size_t.
Gets the IV length for the associated cipher algorithm. The length of the "ivlen" parameter should not exceed that of a size_t.
Gets the IV for the associated cipher ctx.
Gets or sets the cipher specific "num" parameter for the associated cipher ctx. Built-in ciphers typically use this to track how much of the current underlying block has been "used" already.
Gets or sets the AEAD tag for the associated cipher ctx. See EVP_EncryptInit(3)/AEAD Interface.
Gets the tag length to be used for an AEAD cipher for the associated cipher ctx. It returns a default value if it has not been set. The length of the "taglen" parameter should not exceed that of a size_t.
Sets TLSv1.2 AAD information for the associated cipher ctx. TLSv1.2 AAD information is always 13 bytes in length and is as defined for the "additional_data" field described in section 6.2.3.3 of RFC5246.
Gets the length of the tag that will be added to a TLS record for the AEAD tag for the associated cipher ctx. The length of the "tlsaadpad" parameter should not exceed that of a size_t.
Sets the fixed portion of an IV for an AEAD cipher used in a TLS record encryption/ decryption for the associated cipher ctx. TLS record encryption/decryption always occurs "in place" so that the input and output buffers are always the same memory location. AEAD IVs in TLSv1.2 consist of an implicit "fixed" part and an explicit part that varies with every record. Setting a TLS fixed IV changes a cipher to encrypt/decrypt TLS records. TLS records are encrypted/decrypted using a single OP_cipher_cipher call per record. For a record decryption the first bytes of the input buffer will be the explicit part of the IV and the final bytes of the input buffer will be the AEAD tag. The length of the explicit part of the IV and the tag length will depend on the cipher in use and will be defined in the RFC for the relevant ciphersuite. In order to allow for "in place" decryption the plaintext output should be written to the same location in the output buffer that the ciphertext payload was read from, i.e. immediately after the explicit IV.
When encrypting a record the first bytes of the input buffer will be empty to allow space for the explicit IV, as will the final bytes where the tag will be written. The length of the input buffer will include the length of the explicit IV, the payload, and the tag bytes. The cipher implementation should generate the explicit IV and write it to the beginning of the output buffer, do "in place" encryption of the payload and write that to the output buffer, and finally add the tag onto the end of the output buffer.
Whether encrypting or decrypting the value written to *outl in the OP_cipher_cipher call should be the length of the payload excluding the explicit IV length and the tag length.
Sets the IV length to be used for an AEAD cipher for the associated cipher ctx. The length of the "ivlen" parameter should not exceed that of a size_t.
Sets the MAC key used by composite AEAD ciphers such as AES-CBC-HMAC-SHA256.
Gets a implementation specific randomly generated key for the associated cipher ctx. This is currently only supported by 3DES (which sets the key to odd parity).
Used to pass the DER encoded AlgorithmIdentifier parameter to or from the cipher implementation. Functions like EVP_CIPHER_param_to_asn1(3) and EVP_CIPHER_asn1_to_param(3) use this parameter for any implementation that has the flag EVP_CIPH_FLAG_CUSTOM_ASN1 set.
Sets or gets the number of rounds to be used for a cipher. This is used by the RC5 cipher.
Gets or sets the effective keybits used for a RC2 cipher. The length of the "keybits" parameter should not exceed that of a size_t.
Sets the speed option for the associated cipher ctx. This is only supported by AES SIV ciphers which disallow multiple operations by default. Setting "speed" to 1 allows another encrypt or decrypt operation to be performed. This is used for performance testing.
Gets the invocation field generated for encryption. Can only be called after "tlsivfixed" is set. This is only used for GCM mode.
Sets the invocation field used for decryption. Can only be called after "tlsivfixed" is set. This is only used for GCM mode.
Triggers a multiblock tls1 encrypt operation for a tls1 aware cipher that supports sending 4 or 8 records in one go. The cipher performs both the MAC and encrypt stages and constructs the record headers itself. "tls1multi_enc" supplies the output buffer for the encrypt operation, "tls1multi_encin" & "tls1multi_interleave" must also be set in order to supply values to the encrypt operation.
Get the total length of the record returned from the "tls1multi_enc" operation.
Sets or gets the number of records being sent in one go for a tls1 multiblock cipher operation (either 4 or 8 records).
Supplies the data to encrypt for a tls1 multiblock cipher operation.
Sets the maximum send fragment size for a tls1 multiblock cipher operation. It must be set before using "tls1multi_maxbufsz". The length of the "tls1multi_maxsndfrag" parameter should not exceed that of a size_t.
Gets the maximum record length for a tls1 multiblock cipher operation. The length of the "tls1multi_maxbufsz" parameter should not exceed that of a size_t.
Sets the authenticated additional data used by a tls1 multiblock cipher operation. The supplied data consists of 13 bytes of record data containing: Bytes 0-7: The sequence number of the first record Byte 8: The record type Byte 9-10: The protocol version Byte 11-12: Input length (Always 0)
"tls1multi_interleave" must also be set for this operation.
Gets the result of running the "tls1multi_aad" operation.
OP_cipher_newctx() and OP_cipher_dupctx() should return the newly created
provider side cipher context, or NULL on failure.
OP_cipher_encrypt_init(), OP_cipher_decrypt_init(), OP_cipher_update(),
OP_cipher_final(), OP_cipher_cipher(), OP_cipher_get_params(),
OP_cipher_get_ctx_params() and OP_cipher_set_ctx_params() should return 1 for
success or 0 on error.
OP_cipher_gettable_params(), OP_cipher_gettable_ctx_params() and
OP_cipher_settable_ctx_params() should return a constant OSSL_PARAM
array, or NULL if none is offered.
provider(7)
The provider CIPHER interface was introduced in OpenSSL 3.0.
Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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 https://www.openssl.org/source/license.html.