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 B<OSSL_DISPATCH> arrays via 58B<OSSL_ALGORITHM> 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 B<OSSL_DISPATCH> 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 72B<OSSL_DISPATCH> 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 131provider-keymgmt(7)>. 132OSSL_FUNC_asym_cipher_encrypt() performs the actual encryption itself. 133A previously initialised asymmetric cipher context is passed in the I<ctx> 134parameter. 135The data to be encrypted is pointed to by the I<in> parameter which is I<inlen> 136bytes long. 137Unless I<out> is NULL, the encrypted data should be written to the location 138pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in 139length. 140The length of the encrypted data should be written to I<*outlen>. 141If I<out> is NULL then the maximum length of the encrypted data should be 142written to I<*outlen>. 143 144=head2 Decryption Functions 145 146OSSL_FUNC_asym_cipher_decrypt_init() initialises a context for an asymmetric decryption 147given a provider side asymmetric cipher context in the I<ctx> parameter, and a 148pointer to a provider key object in the I<provkey> parameter. 149The I<params>, if not NULL, should be set on the context in a manner similar to 150using OSSL_FUNC_asym_cipher_set_ctx_params(). 151The key object should have been previously generated, loaded or imported into 152the provider using the key management (OSSL_OP_KEYMGMT) operation (see 153provider-keymgmt(7)>. 154 155OSSL_FUNC_asym_cipher_decrypt() performs the actual decryption itself. 156A previously initialised asymmetric cipher context is passed in the I<ctx> 157parameter. 158The data to be decrypted is pointed to by the I<in> parameter which is I<inlen> 159bytes long. 160Unless I<out> is NULL, the decrypted data should be written to the location 161pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in 162length. 163The length of the decrypted data should be written to I<*outlen>. 164If I<out> is NULL then the maximum length of the decrypted data should be 165written to I<*outlen>. 166 167=head2 Asymmetric Cipher Parameters 168 169See L<OSSL_PARAM(3)> for further details on the parameters structure used by 170the OSSL_FUNC_asym_cipher_get_ctx_params() and OSSL_FUNC_asym_cipher_set_ctx_params() 171functions. 172 173OSSL_FUNC_asym_cipher_get_ctx_params() gets asymmetric cipher parameters associated 174with the given provider side asymmetric cipher context I<ctx> and stores them in 175I<params>. 176Passing NULL for I<params> should return true. 177 178OSSL_FUNC_asym_cipher_set_ctx_params() sets the asymmetric cipher parameters associated 179with the given provider side asymmetric cipher context I<ctx> to I<params>. 180Any parameter settings are additional to any that were previously set. 181Passing NULL for I<params> should return true. 182 183Parameters currently recognised by built-in asymmetric cipher algorithms are as 184follows. 185Not all parameters are relevant to, or are understood by all asymmetric cipher 186algorithms: 187 188=over 4 189 190=item "pad-mode" (B<OSSL_ASYM_CIPHER_PARAM_PAD_MODE>) <integer> 191 192The type of padding to be used. The interpretation of this value will depend 193on the algorithm in use. The default provider understands these RSA padding 194modes: 1 (RSA_PKCS1_PADDING), 3 (RSA_NO_PADDING), 1954 (RSA_PKCS1_OAEP_PADDING), 5 (RSA_X931_PADDING), 6 (RSA_PKCS1_PSS_PADDING) and 1967 (RSA_PKCS1_WITH_TLS_PADDING). See L<EVP_PKEY_CTX_set_rsa_padding(3)> for 197further details. 198 199=item "digest" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST>) <UTF8 string> 200 201Gets or sets the name of the OAEP digest algorithm used when OAEP padding is in 202use. 203 204=item "digest" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST>) <UTF8 string> 205 206Gets or sets the name of the digest algorithm used by the algorithm (where 207applicable). 208 209=item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST_PROPS>) <UTF8 string> 210 211Gets or sets the properties to use when fetching the OAEP digest algorithm. 212 213=item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST_PROPS>) <UTF8 string> 214 215Gets or sets the properties to use when fetching the cipher digest algorithm. 216 217=item "mgf1-digest" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST>) <UTF8 string> 218 219Gets or sets the name of the MGF1 digest algorithm used when OAEP or PSS padding 220is in use. 221 222=item "mgf1-digest-props" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS>) <UTF8 string> 223 224Gets or sets the properties to use when fetching the MGF1 digest algorithm. 225 226=item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string> 227 228Gets or sets the OAEP label used when OAEP padding is in use. 229 230=item "tls-client-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer> 231 232The TLS protocol version first requested by the client. See 233B<RSA_PKCS1_WITH_TLS_PADDING> on the page L<EVP_PKEY_CTX_set_rsa_padding(3)>. 234 235=item "tls-negotiated-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer> 236 237The negotiated TLS protocol version. See 238B<RSA_PKCS1_WITH_TLS_PADDING> on the page L<EVP_PKEY_CTX_set_rsa_padding(3)>. 239 240=back 241 242OSSL_FUNC_asym_cipher_gettable_ctx_params() and OSSL_FUNC_asym_cipher_settable_ctx_params() 243get a constant B<OSSL_PARAM> array that describes the gettable and settable 244parameters, i.e. parameters that can be used with OSSL_FUNC_asym_cipherget_ctx_params() 245and OSSL_FUNC_asym_cipher_set_ctx_params() respectively. 246See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor. 247 248=head1 RETURN VALUES 249 250OSSL_FUNC_asym_cipher_newctx() and OSSL_FUNC_asym_cipher_dupctx() should return the newly 251created provider side asymmetric cipher context, or NULL on failure. 252 253All other functions should return 1 for success or 0 on error. 254 255=head1 SEE ALSO 256 257L<provider(7)> 258 259=head1 HISTORY 260 261The provider ASYM_CIPHER interface was introduced in OpenSSL 3.0. 262 263=head1 COPYRIGHT 264 265Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved. 266 267Licensed under the Apache License 2.0 (the "License"). You may not use 268this file except in compliance with the License. You can obtain a copy 269in the file LICENSE in the source distribution or at 270L<https://www.openssl.org/source/license.html>. 271 272=cut 273
