EVP_PKEY_paramgen(3)
EVP_PKEY_keygen(3) OpenSSL EVP_PKEY_keygen(3)
NAME
EVP_PKEY_keygen_init, EVP_PKEY_keygen,
EVP_PKEY_paramgen_init, EVP_PKEY_paramgen,
EVP_PKEY_CTX_set_cb, EVP_PKEY_CTX_get_cb,
EVP_PKEY_CTX_get_keygen_info,
EVP_PKEVP_PKEY_CTX_set_app_data, EVP_PKEY_CTX_get_app_data -
key and parameter generation functions
SYNOPSIS
#include <openssl/evp.h>
int EVP_PKEY_keygen_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
int EVP_PKEY_paramgen_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
typedef int EVP_PKEY_gen_cb(EVP_PKEY_CTX *ctx);
void EVP_PKEY_CTX_set_cb(EVP_PKEY_CTX *ctx, EVP_PKEY_gen_cb *cb);
EVP_PKEY_gen_cb *EVP_PKEY_CTX_get_cb(EVP_PKEY_CTX *ctx);
int EVP_PKEY_CTX_get_keygen_info(EVP_PKEY_CTX *ctx, int idx);
void EVP_PKEY_CTX_set_app_data(EVP_PKEY_CTX *ctx, void *data);
void *EVP_PKEY_CTX_get_app_data(EVP_PKEY_CTX *ctx);
DESCRIPTION
The EVP_PKEY_keygen_init() function initializes a public key
algorithm context using key pkey for a key genration
operation.
The EVP_PKEY_keygen() function performs a key generation
operation, the generated key is written to ppkey.
The functions EVP_PKEY_paramgen_init() and
EVP_PKEY_paramgen() are similar except parameters are
generated.
The function EVP_PKEY_set_cb() sets the key or parameter
generation callback to cb. The function
EVP_PKEY_CTX_get_cb() returns the key or parameter
generation callback.
The function EVP_PKEY_CTX_get_keygen_info() returns
parameters associated with the generation operation. If idx
is -1 the total number of parameters available is returned.
Any non negative value returns the value of that parameter.
EVP_PKEY_CTX_gen_keygen_info() with a non-negative value for
idx should only be called within the generation callback.
If the callback returns 0 then the key genration operation
is aborted and an error occurs. This might occur during a
1.0.2t Last change: 2019-09-10 1
EVP_PKEY_keygen(3) OpenSSL EVP_PKEY_keygen(3)
time consuming operation where a user clicks on a "cancel"
button.
The functions EVP_PKEY_CTX_set_app_data() and
EVP_PKEY_CTX_get_app_data() set and retrieve an opaque
pointer. This can be used to set some application defined
value which can be retrieved in the callback: for example a
handle which is used to update a "progress dialog".
NOTES
After the call to EVP_PKEY_keygen_init() or
EVP_PKEY_paramgen_init() algorithm specific control
operations can be performed to set any appropriate
parameters for the operation.
The functions EVP_PKEY_keygen() and EVP_PKEY_paramgen() can
be called more than once on the same context if several
operations are performed using the same parameters.
The meaning of the parameters passed to the callback will
depend on the algorithm and the specifiic implementation of
the algorithm. Some might not give any useful information at
all during key or parameter generation. Others might not
even call the callback.
The operation performed by key or parameter generation
depends on the algorithm used. In some cases (e.g. EC with a
supplied named curve) the "generation" option merely sets
the appropriate fields in an EVP_PKEY structure.
In OpenSSL an EVP_PKEY structure containing a private key
also contains the public key components and parameters (if
any). An OpenSSL private key is equivalent to what some
libraries call a "key pair". A private key can be used in
functions which require the use of a public key or
parameters.
RETURN VALUES
EVP_PKEY_keygen_init(), EVP_PKEY_paramgen_init(),
EVP_PKEY_keygen() and EVP_PKEY_paramgen() return 1 for
success and 0 or a negative value for failure. In
particular a return value of -2 indicates the operation is
not supported by the public key algorithm.
EXAMPLES
Generate a 2048 bit RSA key:
#include <openssl/evp.h>
#include <openssl/rsa.h>
1.0.2t Last change: 2019-09-10 2
EVP_PKEY_keygen(3) OpenSSL EVP_PKEY_keygen(3)
EVP_PKEY_CTX *ctx;
EVP_PKEY *pkey = NULL;
ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL);
if (!ctx)
/* Error occurred */
if (EVP_PKEY_keygen_init(ctx) <= 0)
/* Error */
if (EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, 2048) <= 0)
/* Error */
/* Generate key */
if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
/* Error */
Generate a key from a set of parameters:
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
EVP_PKEY *pkey = NULL, *param;
/* Assumed param is set up already */
ctx = EVP_PKEY_CTX_new(param);
if (!ctx)
/* Error occurred */
if (EVP_PKEY_keygen_init(ctx) <= 0)
/* Error */
/* Generate key */
if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
/* Error */
Example of generation callback for OpenSSL public key
implementations:
/* Application data is a BIO to output status to */
EVP_PKEY_CTX_set_app_data(ctx, status_bio);
1.0.2t Last change: 2019-09-10 3
EVP_PKEY_keygen(3) OpenSSL EVP_PKEY_keygen(3)
static int genpkey_cb(EVP_PKEY_CTX *ctx)
{
char c='*';
BIO *b = EVP_PKEY_CTX_get_app_data(ctx);
int p;
p = EVP_PKEY_CTX_get_keygen_info(ctx, 0);
if (p == 0) c='.';
if (p == 1) c='+';
if (p == 2) c='*';
if (p == 3) c='\n';
BIO_write(b,&c,1);
(void)BIO_flush(b);
return 1;
}
SEE ALSO
EVP_PKEY_CTX_new(3), EVP_PKEY_encrypt(3),
EVP_PKEY_decrypt(3), EVP_PKEY_sign(3), EVP_PKEY_verify(3),
EVP_PKEY_verify_recover(3), EVP_PKEY_derive(3)
HISTORY
These functions were first added to OpenSSL 1.0.0.
1.0.2t Last change: 2019-09-10 4
Man(1) output converted with
man2html