1=pod 2 3=head1 NAME 4 5provider-asym_cipher - The asym_cipher library E<lt>-E<gt> provider functions 6 7=head1 SYNOPSIS 8 9=for openssl multiple includes 10 11 #include <openssl/core_dispatch.h> 12 #include <openssl/core_names.h> 13 14 /* 15 * None of these are actual functions, but are displayed like this for 16 * the function signatures for functions that are offered as function 17 * pointers in OSSL_DISPATCH arrays. 18 */ 19 20 /* Context management */ 21 void *OSSL_FUNC_asym_cipher_newctx(void *provctx); 22 void OSSL_FUNC_asym_cipher_freectx(void *ctx); 23 void *OSSL_FUNC_asym_cipher_dupctx(void *ctx); 24 25 /* Encryption */ 26 int OSSL_FUNC_asym_cipher_encrypt_init(void *ctx, void *provkey, 27 const OSSL_PARAM params[]); 28 int OSSL_FUNC_asym_cipher_encrypt(void *ctx, unsigned char *out, size_t *outlen, 29 size_t outsize, const unsigned char *in, 30 size_t inlen); 31 32 /* Decryption */ 33 int OSSL_FUNC_asym_cipher_decrypt_init(void *ctx, void *provkey, 34 const OSSL_PARAM params[]); 35 int OSSL_FUNC_asym_cipher_decrypt(void *ctx, unsigned char *out, size_t *outlen, 36 size_t outsize, const unsigned char *in, 37 size_t inlen); 38 39 /* Asymmetric Cipher parameters */ 40 int OSSL_FUNC_asym_cipher_get_ctx_params(void *ctx, OSSL_PARAM params[]); 41 const OSSL_PARAM *OSSL_FUNC_asym_cipher_gettable_ctx_params(void *provctx); 42 int OSSL_FUNC_asym_cipher_set_ctx_params(void *ctx, const OSSL_PARAM params[]); 43 const OSSL_PARAM *OSSL_FUNC_asym_cipher_settable_ctx_params(void *provctx); 44 45=head1 DESCRIPTION 46 47This documentation is primarily aimed at provider authors. See L<provider(7)> 48for further information. 49 50The asymmetric cipher (OSSL_OP_ASYM_CIPHER) operation enables providers to 51implement asymmetric cipher algorithms and make them available to applications 52via the API functions L<EVP_PKEY_encrypt(3)>, 53L<EVP_PKEY_decrypt(3)> and 54other related functions). 55 56All "functions" mentioned here are passed as function pointers between 57F<libcrypto> and the provider in L<OSSL_DISPATCH(3)> arrays via 58L<OSSL_ALGORITHM(3)> arrays that are returned by the provider's 59provider_query_operation() function 60(see L<provider-base(7)/Provider Functions>). 61 62All these "functions" have a corresponding function type definition 63named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the 64function pointer from an L<OSSL_DISPATCH(3)> element named 65B<OSSL_FUNC_{name}>. 66For example, the "function" OSSL_FUNC_asym_cipher_newctx() has these: 67 68 typedef void *(OSSL_FUNC_asym_cipher_newctx_fn)(void *provctx); 69 static ossl_inline OSSL_FUNC_asym_cipher_newctx_fn 70 OSSL_FUNC_asym_cipher_newctx(const OSSL_DISPATCH *opf); 71 72L<OSSL_DISPATCH(3)> arrays are indexed by numbers that are provided as 73macros in L<openssl-core_dispatch.h(7)>, as follows: 74 75 OSSL_FUNC_asym_cipher_newctx OSSL_FUNC_ASYM_CIPHER_NEWCTX 76 OSSL_FUNC_asym_cipher_freectx OSSL_FUNC_ASYM_CIPHER_FREECTX 77 OSSL_FUNC_asym_cipher_dupctx OSSL_FUNC_ASYM_CIPHER_DUPCTX 78 79 OSSL_FUNC_asym_cipher_encrypt_init OSSL_FUNC_ASYM_CIPHER_ENCRYPT_INIT 80 OSSL_FUNC_asym_cipher_encrypt OSSL_FUNC_ASYM_CIPHER_ENCRYPT 81 82 OSSL_FUNC_asym_cipher_decrypt_init OSSL_FUNC_ASYM_CIPHER_DECRYPT_INIT 83 OSSL_FUNC_asym_cipher_decrypt OSSL_FUNC_ASYM_CIPHER_DECRYPT 84 85 OSSL_FUNC_asym_cipher_get_ctx_params OSSL_FUNC_ASYM_CIPHER_GET_CTX_PARAMS 86 OSSL_FUNC_asym_cipher_gettable_ctx_params OSSL_FUNC_ASYM_CIPHER_GETTABLE_CTX_PARAMS 87 OSSL_FUNC_asym_cipher_set_ctx_params OSSL_FUNC_ASYM_CIPHER_SET_CTX_PARAMS 88 OSSL_FUNC_asym_cipher_settable_ctx_params OSSL_FUNC_ASYM_CIPHER_SETTABLE_CTX_PARAMS 89 90An asymmetric cipher algorithm implementation may not implement all of these 91functions. 92In order to be a consistent set of functions a provider must implement 93OSSL_FUNC_asym_cipher_newctx and OSSL_FUNC_asym_cipher_freectx. 94It must also implement both of OSSL_FUNC_asym_cipher_encrypt_init and 95OSSL_FUNC_asym_cipher_encrypt, or both of OSSL_FUNC_asym_cipher_decrypt_init and 96OSSL_FUNC_asym_cipher_decrypt. 97OSSL_FUNC_asym_cipher_get_ctx_params is optional but if it is present then so must 98OSSL_FUNC_asym_cipher_gettable_ctx_params. 99Similarly, OSSL_FUNC_asym_cipher_set_ctx_params is optional but if it is present then 100so must OSSL_FUNC_asym_cipher_settable_ctx_params. 101 102An asymmetric cipher algorithm must also implement some mechanism for generating, 103loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation. 104See L<provider-keymgmt(7)> for further details. 105 106=head2 Context Management Functions 107 108OSSL_FUNC_asym_cipher_newctx() should create and return a pointer to a provider side 109structure for holding context information during an asymmetric cipher operation. 110A pointer to this context will be passed back in a number of the other 111asymmetric cipher operation function calls. 112The parameter I<provctx> is the provider context generated during provider 113initialisation (see L<provider(7)>). 114 115OSSL_FUNC_asym_cipher_freectx() is passed a pointer to the provider side asymmetric 116cipher context in the I<ctx> parameter. 117This function should free any resources associated with that context. 118 119OSSL_FUNC_asym_cipher_dupctx() should duplicate the provider side asymmetric cipher 120context in the I<ctx> parameter and return the duplicate copy. 121 122=head2 Encryption Functions 123 124OSSL_FUNC_asym_cipher_encrypt_init() initialises a context for an asymmetric encryption 125given a provider side asymmetric cipher context in the I<ctx> parameter, and a 126pointer to a provider key object in the I<provkey> parameter. 127The I<params>, if not NULL, should be set on the context in a manner similar to 128using OSSL_FUNC_asym_cipher_set_ctx_params(). 129The key object should have been previously generated, loaded or imported into 130the provider using the key management (OSSL_OP_KEYMGMT) operation (see L<provider-keymgmt(7)>). 131OSSL_FUNC_asym_cipher_encrypt() performs the actual encryption itself. 132A previously initialised asymmetric cipher context is passed in the I<ctx> 133parameter. 134The data to be encrypted is pointed to by the I<in> parameter which is I<inlen> 135bytes long. 136Unless I<out> is NULL, the encrypted data should be written to the location 137pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in 138length. 139The length of the encrypted data should be written to I<*outlen>. 140If I<out> is NULL then the maximum length of the encrypted data should be 141written to I<*outlen>. 142 143=head2 Decryption Functions 144 145OSSL_FUNC_asym_cipher_decrypt_init() initialises a context for an asymmetric decryption 146given a provider side asymmetric cipher context in the I<ctx> parameter, and a 147pointer to a provider key object in the I<provkey> parameter. 148The I<params>, if not NULL, should be set on the context in a manner similar to 149using OSSL_FUNC_asym_cipher_set_ctx_params(). 150The key object should have been previously generated, loaded or imported into 151the provider using the key management (OSSL_OP_KEYMGMT) operation (see 152L<provider-keymgmt(7)>). 153 154OSSL_FUNC_asym_cipher_decrypt() performs the actual decryption itself. 155A previously initialised asymmetric cipher context is passed in the I<ctx> 156parameter. 157The data to be decrypted is pointed to by the I<in> parameter which is I<inlen> 158bytes long. 159Unless I<out> is NULL, the decrypted data should be written to the location 160pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in 161length. 162The length of the decrypted data should be written to I<*outlen>. 163If I<out> is NULL then the maximum length of the decrypted data should be 164written to I<*outlen>. 165 166=head2 Asymmetric Cipher Parameters 167 168See L<OSSL_PARAM(3)> for further details on the parameters structure used by 169the OSSL_FUNC_asym_cipher_get_ctx_params() and OSSL_FUNC_asym_cipher_set_ctx_params() 170functions. 171 172OSSL_FUNC_asym_cipher_get_ctx_params() gets asymmetric cipher parameters associated 173with the given provider side asymmetric cipher context I<ctx> and stores them in 174I<params>. 175Passing NULL for I<params> should return true. 176 177OSSL_FUNC_asym_cipher_set_ctx_params() sets the asymmetric cipher parameters associated 178with the given provider side asymmetric cipher context I<ctx> to I<params>. 179Any parameter settings are additional to any that were previously set. 180Passing NULL for I<params> should return true. 181 182Parameters currently recognised by built-in asymmetric cipher algorithms are as 183follows. 184Not all parameters are relevant to, or are understood by all asymmetric cipher 185algorithms: 186 187=over 4 188 189=item "pad-mode" (B<OSSL_ASYM_CIPHER_PARAM_PAD_MODE>) <UTF8 string> OR <integer> 190 191The type of padding to be used. The interpretation of this value will depend 192on the algorithm in use. 193 194=item "digest" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST>) <UTF8 string> 195 196Gets or sets the name of the OAEP digest algorithm used when OAEP padding is in 197use. 198 199=item "digest" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST>) <UTF8 string> 200 201Gets or sets the name of the digest algorithm used by the algorithm (where 202applicable). 203 204=item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST_PROPS>) <UTF8 string> 205 206Gets or sets the properties to use when fetching the OAEP digest algorithm. 207 208=item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST_PROPS>) <UTF8 string> 209 210Gets or sets the properties to use when fetching the cipher digest algorithm. 211 212=item "mgf1-digest" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST>) <UTF8 string> 213 214Gets or sets the name of the MGF1 digest algorithm used when OAEP or PSS padding 215is in use. 216 217=item "mgf1-digest-props" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS>) <UTF8 string> 218 219Gets or sets the properties to use when fetching the MGF1 digest algorithm. 220 221=item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string ptr> 222 223Gets the OAEP label used when OAEP padding is in use. 224 225=item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string> 226 227Sets the OAEP label used when OAEP padding is in use. 228 229=item "tls-client-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer> 230 231The TLS protocol version first requested by the client. 232 233=item "tls-negotiated-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer> 234 235The negotiated TLS protocol version. 236 237=back 238 239OSSL_FUNC_asym_cipher_gettable_ctx_params() and OSSL_FUNC_asym_cipher_settable_ctx_params() 240get a constant L<OSSL_PARAM(3)> array that describes the gettable and settable 241parameters, i.e. parameters that can be used with OSSL_FUNC_asym_cipherget_ctx_params() 242and OSSL_FUNC_asym_cipher_set_ctx_params() respectively. 243 244=head1 RETURN VALUES 245 246OSSL_FUNC_asym_cipher_newctx() and OSSL_FUNC_asym_cipher_dupctx() should return the newly 247created provider side asymmetric cipher context, or NULL on failure. 248 249All other functions should return 1 for success or 0 on error. 250 251=head1 SEE ALSO 252 253L<provider(7)> 254 255=head1 HISTORY 256 257The provider ASYM_CIPHER interface was introduced in OpenSSL 3.0. 258 259=head1 COPYRIGHT 260 261Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved. 262 263Licensed under the Apache License 2.0 (the "License"). You may not use 264this file except in compliance with the License. You can obtain a copy 265in the file LICENSE in the source distribution or at 266L<https://www.openssl.org/source/license.html>. 267 268=cut 269