=pod =head1 NAME EVP_PKEY_CTX_new, EVP_PKEY_CTX_new_id, EVP_PKEY_CTX_dup, EVP_PKEY_CTX_free - public key algorithm context functions. =head1 SYNOPSIS #include <openssl/evp.h> 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_dup(EVP_PKEY_CTX *ctx); void EVP_PKEY_CTX_free(EVP_PKEY_CTX *ctx); =head1 DESCRIPTION The EVP_PKEY_CTX_new() function allocates public key algorithm context using the algorithm specified in B<pkey> and ENGINE B<e>. The EVP_PKEY_CTX_new_id() function allocates public key algorithm context using the algorithm specified by B<id> and ENGINE B<e>. It is normally used when no B<EVP_PKEY> structure is associated with the operations, for example during parameter generation of key genration for some algorithms. EVP_PKEY_CTX_dup() duplicates the context B<ctx>. EVP_PKEY_CTX_free() frees up the context B<ctx>. =head1 NOTES The B<EVP_PKEY_CTX> structure is an opaque public key algorithm context used by the OpenSSL high level public key API. Contexts B<MUST NOT> be shared between threads: that is it is not permissible to use the same context simultaneously in two threads. =head1 RETURN VALUES EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id(), EVP_PKEY_CTX_dup() returns either the newly allocated B<EVP_PKEY_CTX> structure of B<NULL> if an error occurred. EVP_PKEY_CTX_free() does not return a value. =head1 SEE ALSO L<EVP_PKEY_new(3)|EVP_PKEY_new(3)> =head1 HISTORY These functions were first added to OpenSSL 1.0.0. =cut