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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" EVP_PKEY_CTX_new, EVP_PKEY_CTX_new_id, EVP_PKEY_CTX_new_from_name, EVP_PKEY_CTX_new_from_pkey, EVP_PKEY_CTX_dup, EVP_PKEY_CTX_free, EVP_PKEY_CTX_is_a \&\- public key algorithm context functions .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include \& \& EVP_PKEY_CTX *EVP_PKEY_CTX_new(EVP_PKEY *pkey, ENGINE *e); \& EVP_PKEY_CTX *EVP_PKEY_CTX_new_id(int id, ENGINE *e); \& EVP_PKEY_CTX *EVP_PKEY_CTX_new_from_name(OSSL_LIB_CTX *libctx, \& const char *name, \& const char *propquery); \& EVP_PKEY_CTX *EVP_PKEY_CTX_new_from_pkey(OSSL_LIB_CTX *libctx, \& EVP_PKEY *pkey, \& const char *propquery); \& EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *ctx); \& void EVP_PKEY_CTX_free(EVP_PKEY_CTX *ctx); \& int EVP_PKEY_CTX_is_a(EVP_PKEY_CTX *ctx, const char *keytype); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \fBEVP_PKEY_CTX_new()\fR function allocates public key algorithm context using the \fIpkey\fR key type and \s-1ENGINE\s0 \fIe\fR. .PP The \fBEVP_PKEY_CTX_new_id()\fR function allocates public key algorithm context using the key type specified by \fIid\fR and \s-1ENGINE\s0 \fIe\fR. .PP The \fBEVP_PKEY_CTX_new_from_name()\fR function allocates a public key algorithm context using the library context \fIlibctx\fR (see \s-1\fBOSSL_LIB_CTX\s0\fR\|(3)), the key type specified by \fIname\fR and the property query \fIpropquery\fR. None of the arguments are duplicated, so they must remain unchanged for the lifetime of the returned \fB\s-1EVP_PKEY_CTX\s0\fR or of any of its duplicates. Read further about the possible names in \*(L"\s-1NOTES\*(R"\s0 below. .PP The \fBEVP_PKEY_CTX_new_from_pkey()\fR function allocates a public key algorithm context using the library context \fIlibctx\fR (see \s-1\fBOSSL_LIB_CTX\s0\fR\|(3)) and the algorithm specified by \fIpkey\fR and the property query \fIpropquery\fR. None of the arguments are duplicated, so they must remain unchanged for the lifetime of the returned \fB\s-1EVP_PKEY_CTX\s0\fR or any of its duplicates. .PP \&\fBEVP_PKEY_CTX_new_id()\fR and \fBEVP_PKEY_CTX_new_from_name()\fR are normally used when no \fB\s-1EVP_PKEY\s0\fR structure is associated with the operations, for example during parameter generation or key generation for some algorithms. .PP \&\fBEVP_PKEY_CTX_dup()\fR duplicates the context \fIctx\fR. It is not supported for a keygen operation. .PP \&\fBEVP_PKEY_CTX_free()\fR frees up the context \fIctx\fR. If \fIctx\fR is \s-1NULL,\s0 nothing is done. .PP \&\fBEVP_PKEY_is_a()\fR checks if the key type associated with \fIctx\fR is \fIkeytype\fR. .SH "NOTES" .IX Header "NOTES" .SS "On \fB\s-1EVP_PKEY_CTX\s0\fP" .IX Subsection "On EVP_PKEY_CTX" The \fB\s-1EVP_PKEY_CTX\s0\fR structure is an opaque public key algorithm context used by the OpenSSL high-level public key \s-1API.\s0 Contexts \fB\s-1MUST NOT\s0\fR be shared between threads: that is it is not permissible to use the same context simultaneously in two threads. .SS "On Key Types" .IX Subsection "On Key Types" We mention \*(L"key type\*(R" in this manual, which is the same as \*(L"algorithm\*(R" in most cases, allowing either term to be used interchangeably. There are algorithms where the \fIkey type\fR and the \&\fIalgorithm\fR of the operations that use the keys are not the same, such as \s-1EC\s0 keys being used for \s-1ECDSA\s0 and \s-1ECDH\s0 operations. .PP Key types are given in two different manners: .IP "Legacy \s-1NID\s0 or \s-1EVP_PKEY\s0 type" 4 .IX Item "Legacy NID or EVP_PKEY type" This is the \fIid\fR used with \fBEVP_PKEY_CTX_new_id()\fR. .Sp These are \fB\s-1EVP_PKEY_RSA\s0\fR, \fB\s-1EVP_PKEY_RSA_PSS\s0\fR, \fB\s-1EVP_PKEY_DSA\s0\fR, \&\fB\s-1EVP_PKEY_DH\s0\fR, \fB\s-1EVP_PKEY_EC\s0\fR, \fB\s-1EVP_PKEY_SM2\s0\fR, \fB\s-1EVP_PKEY_X25519\s0\fR, \&\fB\s-1EVP_PKEY_X448\s0\fR, and are used by legacy methods. .IP "Name strings" 4 .IX Item "Name strings" This is the \fIname\fR used with \fBEVP_PKEY_CTX_new_from_name()\fR. .Sp These are names like \*(L"\s-1RSA\*(R", \*(L"DSA\*(R",\s0 and what's available depends on what providers are currently accessible. .Sp The OpenSSL providers offer a set of key types available this way, please see \s-1\fBOSSL_PROVIDER\-FIPS\s0\fR\|(7) and \fBOSSL_PROVIDER\-default\fR\|(7) and related documentation for more information. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBEVP_PKEY_CTX_new()\fR, \fBEVP_PKEY_CTX_new_id()\fR and \fBEVP_PKEY_CTX_dup()\fR return either the newly allocated \fB\s-1EVP_PKEY_CTX\s0\fR structure or \fB\s-1NULL\s0\fR if an error occurred. .PP \&\fBEVP_PKEY_CTX_free()\fR does not return a value. .PP \&\fBEVP_PKEY_CTX_is_a()\fR returns 1 for true and 0 for false. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBEVP_PKEY_new\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" The \fBEVP_PKEY_CTX_new()\fR, \fBEVP_PKEY_CTX_new_id()\fR, \fBEVP_PKEY_CTX_dup()\fR and \&\fBEVP_PKEY_CTX_free()\fR functions were added in OpenSSL 1.0.0. .PP The \fBEVP_PKEY_CTX_new_from_name()\fR and \fBEVP_PKEY_CTX_new_from_pkey()\fR functions were added in OpenSSL 3.0. .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2006\-2021 The OpenSSL Project Authors. All Rights Reserved. .PP 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 .