- NAME
- SYNOPSIS
- DESCRIPTION
- NOTES
- RETURN VALUES
- SEE ALSO
- HISTORY

# NAME

EVP_PKEY_CTX_new, EVP_PKEY_CTX_new_id, EVP_PKEY_CTX_dup, EVP_PKEY_CTX_free - public key algorithm context functions.

# 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);

# DESCRIPTION

The `EVP_PKEY_CTX_new()` function allocates public key algorithm context using the algorithm specified in pkey and ENGINE e.

The `EVP_PKEY_CTX_new_id()` function allocates public key algorithm context using the algorithm specified by id and ENGINE e. It is normally used when no 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 ctx.

`EVP_PKEY_CTX_free()` frees up the context ctx.

# NOTES

The EVP_PKEY_CTX structure is an opaque public key algorithm context used by the OpenSSL high level public key API. Contexts MUST NOT be shared between threads: that is it is not permissible to use the same context simultaneously in two threads.

# RETURN VALUES

`EVP_PKEY_CTX_new()`, `EVP_PKEY_CTX_new_id()`, `EVP_PKEY_CTX_dup()` returns either the newly allocated EVP_PKEY_CTX structure of NULL if an error occurred.

`EVP_PKEY_CTX_free()` does not return a value.

# SEE ALSO

EVP_PKEY_new

# HISTORY

These functions were first added to OpenSSL 1.0.0.