From: Matt Caswell Date: Tue, 29 Oct 2019 09:24:24 +0000 (+0000) Subject: Add documentation for the Asymmetric Cipher Operation X-Git-Tag: openssl-3.0.0-alpha1~956 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=11d876df50d90ec4b26364c4b7d317ea19139e13;p=oweals%2Fopenssl.git Add documentation for the Asymmetric Cipher Operation Reviewed-by: Richard Levitte (Merged from https://github.com/openssl/openssl/pull/10152) --- diff --git a/doc/man7/provider-asymcipher.pod b/doc/man7/provider-asymcipher.pod new file mode 100644 index 0000000000..d0effa89b1 --- /dev/null +++ b/doc/man7/provider-asymcipher.pod @@ -0,0 +1,242 @@ +=pod + +=head1 NAME + +provider-asym_cipher - The asym_cipher library E-E provider functions + +=head1 SYNOPSIS + +=for openssl multiple includes + + #include + #include + + /* + * 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_asym_cipher_newctx(void *provctx); + void OP_asym_cipher_freectx(void *ctx); + void *OP_asym_cipher_dupctx(void *ctx); + + /* Encryption */ + int OP_asym_cipher_encrypt_init(void *ctx, void *provkey); + int OP_asym_cipher_encrypt(void *ctx, unsigned char *out, size_t *outlen, + size_t outsize, const unsigned char *in, + size_t inlen); + + /* Decryption */ + int OP_asym_cipher_decrypt_init(void *ctx, void *provkey); + int OP_asym_cipher_decrypt(void *ctx, unsigned char *out, size_t *outlen, + size_t outsize, const unsigned char *in, + size_t inlen); + + /* Asymmetric Cipher parameters */ + int OP_asym_cipher_get_ctx_params(void *ctx, OSSL_PARAM params[]); + const OSSL_PARAM *OP_asym_cipher_gettable_ctx_params(void); + int OP_asym_cipher_set_ctx_params(void *ctx, const OSSL_PARAM params[]); + const OSSL_PARAM *OP_asym_cipher_settable_ctx_params(void); + +=head1 DESCRIPTION + +This documentation is primarily aimed at provider authors. See L +for further information. + +The asymmetric cipher (OSSL_OP_ASYM_CIPHER) operation enables providers to +implement asymmetric cipher algorithms and make them available to applications +via the API functions L, L, +L, L (as well +as other related functions). + +All "functions" mentioned here are passed as function pointers between +F and the provider in B arrays via +B arrays that are returned by the provider's +provider_query_operation() function +(see L). + +All these "functions" have a corresponding function type definition +named B, and a helper function to retrieve the +function pointer from an B element named +B. +For example, the "function" OP_asym_cipher_newctx() has these: + + typedef void *(OSSL_OP_asym_cipher_newctx_fn)(void *provctx); + static ossl_inline OSSL_OP_asym_cipher_newctx_fn + OSSL_get_OP_asym_cipher_newctx(const OSSL_DISPATCH *opf); + +B arrays are indexed by numbers that are provided as +macros in L, as follows: + + OP_asym_cipher_newctx OSSL_FUNC_ASYM_CIPHER_NEWCTX + OP_asym_cipher_freectx OSSL_FUNC_ASYM_CIPHER_FREECTX + OP_asym_cipher_dupctx OSSL_FUNC_ASYM_CIPHER_DUPCTX + + OP_asym_cipher_encrypt_init OSSL_FUNC_ASYM_CIPHER_ENCRYPT_INIT + OP_asym_cipher_encrypt OSSL_FUNC_ASYM_CIPHER_ENCRYPT + + OP_asym_cipher_decrypt_init OSSL_FUNC_ASYM_CIPHER_DECRYPT_INIT + OP_asym_cipher_decrypt OSSL_FUNC_ASYM_CIPHER_DECRYPT + + OP_asym_cipher_get_ctx_params OSSL_FUNC_ASYM_CIPHER_GET_CTX_PARAMS + OP_asym_cipher_gettable_ctx_params OSSL_FUNC_ASYM_CIPHER_GETTABLE_CTX_PARAMS + OP_asym_cipher_set_ctx_params OSSL_FUNC_ASYM_CIPHER_SET_CTX_PARAMS + OP_asym_cipher_settable_ctx_params OSSL_FUNC_ASYM_CIPHER_SETTABLE_CTX_PARAMS + +An asymmetric cipher algorithm implementation may not implement all of these +functions. +In order to be a consistent set of functions a provider must implement +OP_asym_cipher_newctx and OP_asym_cipher_freectx. +It must also implement both of OP_asym_cipher_encrypt_init and +OP_asym_cipher_encrypt, or both of OP_asym_cipher_decrypt_init and +OP_asym_cipher_decrypt. +OP_asym_cipher_get_ctx_params is optional but if it is present then so must +OP_asym_cipher_gettable_ctx_params. +Similarly, OP_asym_cipher_set_ctx_params is optional but if it is present then +so must OP_asym_cipher_settable_ctx_params. + +An asymmetric cipher algorithm must also implement some mechanism for generating, +loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation. +See L for further details. + +=head2 Context Management Functions + +OP_asym_cipher_newctx() should create and return a pointer to a provider side +structure for holding context information during an asymmetric cipher operation. +A pointer to this context will be passed back in a number of the other +asymmetric cipher operation function calls. +The parameter I is the provider context generated during provider +initialisation (see L). + +OP_asym_cipher_freectx() is passed a pointer to the provider side asymmetric +cipher context in the I parameter. +This function should free any resources associated with that context. + +OP_asym_cipher_dupctx() should duplicate the provider side asymmetric cipher +context in the I parameter and return the duplicate copy. + +=head2 Encryption Functions + +OP_asym_cipher_encrypt_init() initialises a context for an asymmetric encryption +given a provider side asymmetric cipher context in the I parameter, and a +pointer to a provider key object in the I parameter. +The key object should have been previously generated, loaded or imported into +the provider using the key management (OSSL_OP_KEYMGMT) operation (see +provider-keymgmt(7)>. + +OP_asym_cipher_encrypt() performs the actual encryption itself. +A previously initialised asymmetric cipher context is passed in the I +parameter. +The data to be encrypted is pointed to by the I parameter which is I +bytes long. +Unless I is NULL, the encrypted data should be written to the location +pointed to by the I parameter and it should not exceed I bytes in +length. +The length of the encrypted data should be written to I<*outlen>. +If I is NULL then the maximum length of the encrypted data should be +written to I<*outlen>. + +=head2 Decryption Functions + +OP_asym_cipher_decrypt_init() initialises a context for an asymmetric decryption +given a provider side asymmetric cipher context in the I parameter, and a +pointer to a provider key object in the I parameter. +The key object should have been previously generated, loaded or imported into +the provider using the key management (OSSL_OP_KEYMGMT) operation (see +provider-keymgmt(7)>. + +OP_asym_cipher_decrypt() performs the actual decryption itself. +A previously initialised asymmetric cipher context is passed in the I +parameter. +The data to be decrypted is pointed to by the I parameter which is I +bytes long. +Unless I is NULL, the decrypted data should be written to the location +pointed to by the I parameter and it should not exceed I bytes in +length. +The length of the decrypted data should be written to I<*outlen>. +If I is NULL then the maximum length of the decrypted data should be +written to I<*outlen>. + +=head2 Asymmetric Cipher Parameters + +See L for further details on the parameters structure used by +the OP_asym_cipher_get_ctx_params() and OP_asym_cipher_set_ctx_params() +functions. + +OP_asym_cipher_get_ctx_params() gets asymmetric cipher parameters associated +with the given provider side asymmetric cipher context I and stores them in +I. +OP_asym_cipher_set_ctx_params() sets the asymmetric cipher parameters associated +with the given provider side asymmetric cipher context I to I. +Any parameter settings are additional to any that were previously set. + +Parameters currently recognised by built-in asymmetric cipher algorithms are as +follows. +Not all parameters are relevant to, or are understood by all asymmetric cipher +algorithms: + +=over 4 + +=item "pad-mode" (B) + +=item "digest" (B) + +Gets or sets the name of the OAEP digest algorithm used when OAEP padding is in +use. + +=item "digest-props" (B) + +Gets or sets the properties to use when fetching the OAEP digest algorithm. + +=item "mgf1-digest" (B) + +Gets or sets the name of the MGF1 digest algorithm used when OAEP or PSS padding +is in use. + +=item "mgf1-digest-props" (B) + +Gets or sets the properties to use when fetching the MGF1 digest algorithm. + +=item "oaep-label" (B) + +Gets or sets the OAEP label used when OAEP padding is in use. + +=item "oaep-label-len" (B) + +Gets the length of an OAEP label when OAEP padding is in use. + +=back + +OP_asym_cipher_gettable_ctx_params() and OP_asym_cipher_settable_ctx_params() +get a constant B array that describes the gettable and settable +parameters, i.e. parameters that can be used with OP_asym_cipherget_ctx_params() +and OP_asym_cipher_set_ctx_params() respectively. +See L for the use of B as parameter descriptor. + +=head1 RETURN VALUES + +OP_asym_cipher_newctx() and OP_asym_cipher_dupctx() should return the newly +created provider side asymmetric cipher context, or NULL on failure. + +All other functions should return 1 for success or 0 on error. + +=head1 SEE ALSO + +L + +=head1 HISTORY + +The provider ASYM_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. + +=cut