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Title "PROVIDER-SIGNATURE 7"
way too many mistakes in technical documents.
The signature (\s-1OSSL_OP_SIGNATURE\s0) operation enables providers to implement signature algorithms and make them available to applications via the \s-1API\s0 functions EVP_PKEY_sign\|(3), \fBEVP_PKEY_verify\|(3), and EVP_PKEY_verify_recover\|(3) (as well as other related functions).
All \*(L"functions\*(R" mentioned here are passed as function pointers between \fIlibcrypto and the provider in \s-1OSSL_DISPATCH\s0\|(3) arrays via \s-1OSSL_ALGORITHM\s0\|(3) arrays that are returned by the provider's \fBprovider_query_operation() function (see \*(L"Provider Functions\*(R" in provider-base\|(7)).
All these \*(L"functions\*(R" have a corresponding function type definition named OSSL_FUNC_{name}_fn, and a helper function to retrieve the function pointer from an \s-1OSSL_DISPATCH\s0\|(3) element named \fBOSSL_FUNC_{name}. For example, the \*(L"function\*(R" OSSL_FUNC_signature_newctx() has these:
.Vb 3 typedef void *(OSSL_FUNC_signature_newctx_fn)(void *provctx, const char *propq); static ossl_inline OSSL_FUNC_signature_newctx_fn OSSL_FUNC_signature_newctx(const OSSL_DISPATCH *opf); .Ve
\s-1OSSL_DISPATCH\s0\|(3) arrays are indexed by numbers that are provided as macros in openssl-core_dispatch.h\|(7), as follows:
.Vb 3 OSSL_FUNC_signature_newctx OSSL_FUNC_SIGNATURE_NEWCTX OSSL_FUNC_signature_freectx OSSL_FUNC_SIGNATURE_FREECTX OSSL_FUNC_signature_dupctx OSSL_FUNC_SIGNATURE_DUPCTX \& OSSL_FUNC_signature_sign_init OSSL_FUNC_SIGNATURE_SIGN_INIT OSSL_FUNC_signature_sign OSSL_FUNC_SIGNATURE_SIGN \& OSSL_FUNC_signature_verify_init OSSL_FUNC_SIGNATURE_VERIFY_INIT OSSL_FUNC_signature_verify OSSL_FUNC_SIGNATURE_VERIFY \& OSSL_FUNC_signature_verify_recover_init OSSL_FUNC_SIGNATURE_VERIFY_RECOVER_INIT OSSL_FUNC_signature_verify_recover OSSL_FUNC_SIGNATURE_VERIFY_RECOVER \& OSSL_FUNC_signature_digest_sign_init OSSL_FUNC_SIGNATURE_DIGEST_SIGN_INIT OSSL_FUNC_signature_digest_sign_update OSSL_FUNC_SIGNATURE_DIGEST_SIGN_UPDATE OSSL_FUNC_signature_digest_sign_final OSSL_FUNC_SIGNATURE_DIGEST_SIGN_FINAL OSSL_FUNC_signature_digest_sign OSSL_FUNC_SIGNATURE_DIGEST_SIGN \& OSSL_FUNC_signature_digest_verify_init OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_INIT OSSL_FUNC_signature_digest_verify_update OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_UPDATE OSSL_FUNC_signature_digest_verify_final OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_FINAL OSSL_FUNC_signature_digest_verify OSSL_FUNC_SIGNATURE_DIGEST_VERIFY \& OSSL_FUNC_signature_get_ctx_params OSSL_FUNC_SIGNATURE_GET_CTX_PARAMS OSSL_FUNC_signature_gettable_ctx_params OSSL_FUNC_SIGNATURE_GETTABLE_CTX_PARAMS OSSL_FUNC_signature_set_ctx_params OSSL_FUNC_SIGNATURE_SET_CTX_PARAMS OSSL_FUNC_signature_settable_ctx_params OSSL_FUNC_SIGNATURE_SETTABLE_CTX_PARAMS \& OSSL_FUNC_signature_get_ctx_md_params OSSL_FUNC_SIGNATURE_GET_CTX_MD_PARAMS OSSL_FUNC_signature_gettable_ctx_md_params OSSL_FUNC_SIGNATURE_GETTABLE_CTX_MD_PARAMS OSSL_FUNC_signature_set_ctx_md_params OSSL_FUNC_SIGNATURE_SET_CTX_MD_PARAMS OSSL_FUNC_signature_settable_ctx_md_params OSSL_FUNC_SIGNATURE_SETTABLE_CTX_MD_PARAMS .Ve
A signature algorithm implementation may not implement all of these functions. In order to be a consistent set of functions we must have at least a set of context functions (OSSL_FUNC_signature_newctx and OSSL_FUNC_signature_freectx) as well as a set of \*(L"signature\*(R" functions, i.e. at least one of:
0
OSSL_FUNC_signature_set_ctx_params and OSSL_FUNC_signature_settable_ctx_params are optional, but if one of them is present then the other one must also be present. The same applies to OSSL_FUNC_signature_get_ctx_params and OSSL_FUNC_signature_gettable_ctx_params, as well as the \*(L"md_params\*(R" functions. The OSSL_FUNC_signature_dupctx function is optional.
A signature algorithm must also implement some mechanism for generating, loading or importing keys via the key management (\s-1OSSL_OP_KEYMGMT\s0) operation. See provider-keymgmt\|(7) for further details.
\fBOSSL_FUNC_signature_freectx() is passed a pointer to the provider side signature context in the ctx parameter. This function should free any resources associated with that context.
\fBOSSL_FUNC_signature_dupctx() should duplicate the provider side signature context in the ctx parameter and return the duplicate copy.
\fBOSSL_FUNC_signature_sign() performs the actual signing itself. A previously initialised signature context is passed in the ctx parameter. The data to be signed is pointed to be the tbs parameter which is tbslen bytes long. Unless sig is \s-1NULL,\s0 the signature should be written to the location pointed to by the sig parameter and it should not exceed sigsize bytes in length. The length of the signature should be written to *siglen. If sig is \s-1NULL\s0 then the maximum length of the signature should be written to \fI*siglen.
\fBOSSL_FUNC_signature_verify() performs the actual verification itself. A previously initialised signature context is passed in the ctx parameter. The data that the signature covers is pointed to be the tbs parameter which is tbslen bytes long. The signature is pointed to by the sig parameter which is siglen bytes long.
\fBOSSL_FUNC_signature_verify_recover() performs the actual verify recover itself. A previously initialised signature context is passed in the ctx parameter. The signature is pointed to by the sig parameter which is siglen bytes long. Unless rout is \s-1NULL,\s0 the recovered data should be written to the location pointed to by rout which should not exceed routsize bytes in length. The length of the recovered data should be written to *routlen. If rout is \s-1NULL\s0 then the maximum size of the output buffer is written to the routlen parameter.
\fBOSSL_FUNC_signature_digest_sign_update() provides data to be signed in the data parameter which should be of length datalen. A previously initialised signature context is passed in the ctx parameter. This function may be called multiple times to cumulatively add data to be signed.
\fBOSSL_FUNC_signature_digest_sign_final() finalises a signature operation previously started through OSSL_FUNC_signature_digest_sign_init() and \fBOSSL_FUNC_signature_digest_sign_update() calls. Once finalised no more data will be added through OSSL_FUNC_signature_digest_sign_update(). A previously initialised signature context is passed in the ctx parameter. Unless sig is \s-1NULL,\s0 the signature should be written to the location pointed to by the sig parameter and it should not exceed sigsize bytes in length. The length of the signature should be written to *siglen. If sig is \s-1NULL\s0 then the maximum length of the signature should be written to *siglen.
\fBOSSL_FUNC_signature_digest_sign() implements a \*(L"one shot\*(R" digest sign operation previously started through OSSL_FUNC_signature_digeset_sign_init(). A previously initialised signature context is passed in the ctx parameter. The data to be signed is in tbs which should be tbslen bytes long. Unless sig is \s-1NULL,\s0 the signature should be written to the location pointed to by the sig parameter and it should not exceed sigsize bytes in length. The length of the signature should be written to *siglen. If sig is \s-1NULL\s0 then the maximum length of the signature should be written to *siglen.
\fBOSSL_FUNC_signature_digest_verify_update() provides data to be verified in the data parameter which should be of length datalen. A previously initialised verification context is passed in the ctx parameter. This function may be called multiple times to cumulatively add data to be verified.
\fBOSSL_FUNC_signature_digest_verify_final() finalises a verification operation previously started through OSSL_FUNC_signature_digest_verify_init() and \fBOSSL_FUNC_signature_digest_verify_update() calls. Once finalised no more data will be added through OSSL_FUNC_signature_digest_verify_update(). A previously initialised verification context is passed in the ctx parameter. The signature to be verified is in sig which is siglen bytes long.
\fBOSSL_FUNC_signature_digest_verify() implements a \*(L"one shot\*(R" digest verify operation previously started through OSSL_FUNC_signature_digeset_verify_init(). A previously initialised verification context is passed in the ctx parameter. The data to be verified is in tbs which should be tbslen bytes long. The signature to be verified is in sig which is siglen bytes long.
\fBOSSL_FUNC_signature_get_ctx_params() gets signature parameters associated with the given provider side signature context ctx and stored them in params. Passing \s-1NULL\s0 for params should return true.
\fBOSSL_FUNC_signature_set_ctx_params() sets the signature parameters associated with the given provider side signature context ctx to params. Any parameter settings are additional to any that were previously set. Passing \s-1NULL\s0 for params should return true.
Common parameters currently recognised by built-in signature algorithms are as follows. Item "digest (OSSL_SIGNATURE_PARAM_DIGEST) <UTF8 string>" Get or sets the name of the digest algorithm used for the input to the signature functions. It is required in order to calculate the \*(L"algorithm-id\*(R". Item "properties (OSSL_SIGNATURE_PARAM_PROPERTIES) <UTF8 string>" Sets the name of the property query associated with the \*(L"digest\*(R" algorithm. \s-1NULL\s0 is used if this optional value is not set. Item "digest-size (OSSL_SIGNATURE_PARAM_DIGEST_SIZE) <unsigned integer>" Gets or sets the output size of the digest algorithm used for the input to the signature functions. The length of the \*(L"digest-size\*(R" parameter should not exceed that of a size_t. Item "algorithm-id (OSSL_SIGNATURE_PARAM_ALGORITHM_ID) <octet string>" Gets the \s-1DER\s0 encoded AlgorithmIdentifier that corresponds to the combination of signature algorithm and digest algorithm for the signature operation. Item "kat (OSSL_SIGNATURE_PARAM_KAT) <unsigned integer>" Sets a flag to modify the sign operation to return an error if the initial calculated signature is invalid. In the normal mode of operation - new random values are chosen until the signature operation succeeds. By default it retries until a signature is calculated. Setting the value to 0 causes the sign operation to retry, otherwise the sign operation is only tried once and returns whether or not it was successful. Known answer tests can be performed if the random generator is overridden to supply known values that either pass or fail.
\fBOSSL_FUNC_signature_gettable_ctx_params() and OSSL_FUNC_signature_settable_ctx_params() get a constant \s-1OSSL_PARAM\s0\|(3) array that describes the gettable and settable parameters, i.e. parameters that can be used with OSSL_FUNC_signature_get_ctx_params() and \fBOSSL_FUNC_signature_set_ctx_params() respectively.
\fBOSSL_FUNC_signature_get_md_ctx_params() gets digest parameters associated with the given provider side digest signature context ctx and stores them in params. Passing \s-1NULL\s0 for params should return true.
\fBOSSL_FUNC_signature_set_ms_ctx_params() sets the digest parameters associated with the given provider side digest signature context ctx to params. Any parameter settings are additional to any that were previously set. Passing \s-1NULL\s0 for params should return true.
Parameters currently recognised by built-in signature algorithms are the same as those for built-in digest algorithms. See \*(L"Digest Parameters\*(R" in provider-digest\|(7) for further information.
\fBOSSL_FUNC_signature_gettable_md_ctx_params() and OSSL_FUNC_signature_settable_md_ctx_params() get a constant \s-1OSSL_PARAM\s0\|(3) array that describes the gettable and settable digest parameters, i.e. parameters that can be used with \fBOSSL_FUNC_signature_get_md_ctx_params() and OSSL_FUNC_signature_set_md_ctx_params() respectively.
\fBOSSL_FUNC_signature_gettable_ctx_params(), OSSL_FUNC_signature_settable_ctx_params(), \fBOSSL_FUNC_signature_gettable_md_ctx_params() and OSSL_FUNC_signature_settable_md_ctx_params(), return the gettable or settable parameters in a constant \s-1OSSL_PARAM\s0\|(3) array.
All other functions should return 1 for success or 0 on error.
Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.