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diff --git a/doc/man7/provider-cipher.pod b/doc/man7/provider-cipher.pod new file mode 100644 index 0000000000..08cfebfb25 --- /dev/null +++ b/doc/man7/provider-cipher.pod @@ -0,0 +1,316 @@ +=pod + +=head1 NAME + +provider-cipher - The cipher library E<lt>-E<gt> provider functions + +=head1 SYNOPSIS + +=for comment multiple includes + + #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 parameters */ + int OP_cipher_get_params(OSSL_PARAM params[]); + int OP_cipher_ctx_get_params(void *cctx, OSSL_PARAM params[]); + int OP_cipher_ctx_set_params(void *cctx, const OSSL_PARAM params[]); + +=head1 DESCRIPTION + +This documentation is primarily aimed at provider authors. See L<provider(7)> +for further information. + +The CIPHER operation enables providers to implement cipher algorithms and make +them available to applications via the API functions L<EVP_EncryptInit_ex(3)>, +L<EVP_EncryptUpdate(3)> and L<EVP_EncryptFinal(3)> (as well as the decrypt +equivalents and other related functions). + +All "functions" mentioned here are passed as function pointers between +F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via +B<OSSL_ALGORITHM> arrays that are returned by the provider's +provider_query_operation() function +(see L<provider-base(7)/Provider Functions>). + +All these "functions" have a corresponding function type definition +named B<OSSL_{name}_fn>, and a helper function to retrieve the +function pointer from an B<OSSL_DISPATCH> element named +B<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); + +B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as +macros in L<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_ctx_get_params OSSL_FUNC_CIPHER_CTX_GET_PARAMS + OP_cipher_ctx_set_params OSSL_FUNC_CIPHER_CTX_SET_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. + +=head2 Context Management Functions + +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 paramater B<provctx> is the provider context generated during provider +initialisation (see L<provider(3)>). + +OP_cipher_freectx() is passed a pointer to the provider side cipher context in +the B<cctx> parameter. +This function should free any resources associated with that context. + +OP_cipher_dupctx() should duplicate the provider side cipher context in the +B<cctx> parameter and return the duplicate copy. + +=head2 Encryption/Decryption Functions + +OP_cipher_encrypt_init() initialises a cipher operation for encryption given a +newly created provider side cipher context in the B<cctx> paramter. +The key to be used is given in B<key> which is B<keylen> bytes long. +The IV to be used is given in B<iv> which is B<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 B<cctx> parameter contains a pointer to a previously initialised provider +side context. +OP_cipher_update() should encrypt/decrypt B<inl> bytes of data at the location +pointed to by B<in>. +The encrypted data should be stored in B<out> and the amount of data written to +B<*outl> which should not exceed B<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. +B<out> may be the same location as B<in> but it should not partially overlap. +The same expectations apply to B<outsize> as documented for +L<EVP_EncryptUpdate(3)> and L<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 B<cctx> parameter contains a pointer to the provider side context. +Any final encryption/decryption output should be written to B<out> and the +amount of data written to B<*outl> which should not exceed B<outsize> bytes. +The same expectations apply to B<outsize> as documented for +L<EVP_EncryptFinal(3)> and L<EVP_DecryptFinal(3)>. + +OP_cipher_cipher() performs encryption/decryption using the provider side cipher +context in the B<cctx> paramter 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 +L<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 B<in>, and it will be B<inl> bytes +in length. +The output from the encryption/decryption should be stored in B<out> and the +amount of data stored should be put in B<*outl> which should be no more than +B<outsize> bytes. + +=head2 Cipher Parameters + +See L<OSSL_PARAM(3)> for further details on the parameters structure used by +these functions. + +OP_cipher_get_params() gets details of parameter values associated with the +provider algorithm and stores them in B<params>. + +OP_cipher_ctx_set_params() sets cipher parameters associated with the given +provider side cipher context B<cctx> to B<params>. +Any parameter settings are additional to any that were previously set. + +OP_cipher_ctx_get_params() gets details of currently set parameter values +associated with the given provider side cipher context B<cctx> and stores them +in B<params>. + +Parameters currently recognised by built-in ciphers are as follows. Not all +parameters are relevant to, or are understood by all ciphers: + +=over 4 + +=item B<OSSL_CIPHER_PARAM_PADDING> (int) + +Sets the padding mode for the associated cipher ctx. +Setting a value of 1 will turn padding on. +Setting a vlue of 0 will turn padding off. + +=item B<OSSL_CIPHER_PARAM_MODE> (int) + +Gets the mode for the associated cipher algorithm. +See L<EVP_CIPHER_mode(3)> for a list of valid modes. + +=item B<OSSL_CIPHER_PARAM_BLOCK_SIZE> (int) + +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. + +=item B<OSSL_CIPHER_PARAM_FLAGS> (ulong) + +Gets any flags for the associated cipher algorithm. +See L<EVP_CIPHER_meth_set_flags(3)> for a list of currently defined cipher +flags. + +=item B<OSSL_CIPHER_PARAM_KEYLEN> (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. + +=item B<OSSL_CIPHER_PARAM_IVLEN> (int) + +Gets the IV length for the associated cipher algorithm. + +=item B<OSSL_CIPHER_PARAM_IV> (octet_string OR octet_ptr) + +Gets the IV for the associated cipher ctx. + +=item B<OSSL_CIPHER_PARAM_NUM> (int) + +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. + +=item B<OSSL_CIPHER_PARAM_AEAD_TAG> (octet_string) + +Gets or sets the AEAD tag for the associated cipher ctx. +See L<EVP_EncryptInit(3)/AEAD Interface>. + +=item B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD> (octet_string) + +=for comment TODO(3.0): Consider changing this interface so that all ciphers +use the standard AEAD interface - rather than having this special purpose +interface for TLS + +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. + +=item B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD> (size_t) + +Gets the length of the tag that will be added to a TLS record for the AEAD +tag for the associated cipher ctx. + +=item B<OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED> (octet_string) + +=for comment TODO(3.0): This interface needs completely redesigning! + +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 explict +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 B<*outl> in the +OP_cipher_cipher call should be the length of the payload excluding the explicit +IV length and the tag length. + +=item B<OSSL_CIPHER_PARAM_AEAD_IVLEN> (size_t) + +Sets the IV length to be used for an AEAD cipher for the associated cipher ctx. + +=back + +=head1 RETURN VALUES + +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_ctx_get_params() and OP_cipher_ctx_set_params() should return 1 for +success or 0 on error. + +=head1 SEE ALSO + +L<provider(7)> + +=head1 HISTORY + +The provider CIPHER interface was introduced in OpenSSL 3.0. + +=head1 COPYRIGHT + +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 +L<https://www.openssl.org/source/license.html>. + +=cut |