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+=pod
+
+=head1 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_PKEY_CTX_set_app_data,
+EVP_PKEY_CTX_get_app_data,
+EVP_PKEY_gen_cb, EVP_PKEY_check, EVP_PKEY_public_check,
+EVP_PKEY_param_check
+- key and parameter generation and check functions
+
+=head1 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);
+
+ int EVP_PKEY_check(EVP_PKEY_CTX *ctx);
+ int EVP_PKEY_public_check(EVP_PKEY_CTX *ctx);
+ int EVP_PKEY_param_check(EVP_PKEY_CTX *ctx);
+
+=head1 DESCRIPTION
+
+The EVP_PKEY_keygen_init() function initializes a public key algorithm
+context using key B<pkey> for a key generation operation.
+
+The EVP_PKEY_keygen() function performs a key generation operation, the
+generated key is written to B<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 B<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 B<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
+B<idx> should only be called within the generation callback.
+
+If the callback returns 0 then the key generation operation is aborted and an
+error occurs. This might occur during a 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".
+
+EVP_PKEY_check() validates the key-pair given by B<ctx>. This function first tries
+to use customized key check method in B<EVP_PKEY_METHOD> if it's present; otherwise
+it calls a default one defined in B<EVP_PKEY_ASN1_METHOD>.
+
+EVP_PKEY_public_check() validates the public component of the key-pair given by B<ctx>.
+This function first tries to use customized key check method in B<EVP_PKEY_METHOD>
+if it's present; otherwise it calls a default one defined in B<EVP_PKEY_ASN1_METHOD>.
+
+EVP_PKEY_param_check() validates the algorithm parameters of the key-pair given by B<ctx>.
+This function first tries to use customized key check method in B<EVP_PKEY_METHOD>
+if it's present; otherwise it calls a default one defined in B<EVP_PKEY_ASN1_METHOD>.
+
+=head1 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 specific 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.
+
+=head1 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.
+
+EVP_PKEY_check(), EVP_PKEY_public_check() and EVP_PKEY_param_check() return 1
+for success or others for failure. They return -2 if the operation is not supported
+for the specific algorithm.
+
+=head1 EXAMPLES
+
+Generate a 2048 bit RSA key:
+
+ #include <openssl/evp.h>
+ #include <openssl/rsa.h>
+
+ 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;
+ ENGINE *eng;
+ EVP_PKEY *pkey = NULL, *param;
+
+ /* Assumed param, eng are set up already */
+ ctx = EVP_PKEY_CTX_new(param, eng);
+ 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);
+
+ static int genpkey_cb(EVP_PKEY_CTX *ctx)
+ {
+ char c = '*';
+ BIO *b = EVP_PKEY_CTX_get_app_data(ctx);
+ int 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;
+ }
+
+=head1 SEE ALSO
+
+L<EVP_PKEY_CTX_new(3)>,
+L<EVP_PKEY_encrypt(3)>,
+L<EVP_PKEY_decrypt(3)>,
+L<EVP_PKEY_sign(3)>,
+L<EVP_PKEY_verify(3)>,
+L<EVP_PKEY_verify_recover(3)>,
+L<EVP_PKEY_derive(3)>
+
+=head1 HISTORY
+
+These functions were first added to OpenSSL 1.0.0.
+
+EVP_PKEY_check(), EVP_PKEY_public_check() and EVP_PKEY_param_check() were added
+in OpenSSL 1.1.1.
+
+=head1 COPYRIGHT
+
+Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the OpenSSL license (the "License"). You may not use
+this file except in compliance with the License. You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
+
+=cut