EVP: Add new domparams and key generation functionality

The following functions are added:

EVP_PKEY_gen_set_params(), replacing the older EVP_PKEY_CTX_ctrl()
EVP_PKEY_gen(), replacing both EVP_PKEY_keygen() and EVP_PKEY_paramgen()

These functions are made to work together with already existing domparams
and key generation functionality: EVP_PKEY_CTX_new_provided(),
EVP_PKEY_paramgen_init(), EVP_PKEY_keygen_init(), etc.

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10289)

1 files changed, 57 insertions, 22 deletions

diff --git a/doc/man3/EVP_PKEY_keygen.pod b/doc/man3/EVP_PKEY_gen.pod
index e326b82ffa..212ea2a742 100644
--- a/doc/man3/EVP_PKEY_keygen.pod
+++ b/doc/man3/EVP_PKEY_gen.pod
@@ -2,11 +2,12 @@
 
 =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_keygen_init, EVP_PKEY_paramgen_init, EVP_PKEY_gen,
+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_gen_cb,
+EVP_PKEY_paramgen, EVP_PKEY_keygen
 - key and parameter generation and check functions
 
 =head1 SYNOPSIS
@@ -14,9 +15,10 @@ EVP_PKEY_gen_cb
  #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_gen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
  int EVP_PKEY_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
+ int EVP_PKEY_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
 
  typedef int EVP_PKEY_gen_cb(EVP_PKEY_CTX *ctx);
 
@@ -30,24 +32,51 @@ EVP_PKEY_gen_cb
 
 =head1 DESCRIPTION
 
-The EVP_PKEY_keygen_init() function initializes a public key algorithm
-context using key B<pkey> for a key generation operation.
+Generating keys is sometimes straight forward, just generate the key's
+numbers and be done with it.  However, there are certain key types that need
+key parameters, often called domain parameters but not necessarily limited
+to that, that also need to be generated.  In addition to this, the caller
+may want to set user provided generation parameters that further affect key
+parameter or key generation, such as the desired key size.
+
+To flexibly allow all that's just been described, key parameter and key
+generation is divided into an initialization of a key algorithm context,
+functions to set user provided parameters, and finally the key parameter or
+key generation function itself.
+
+The key algorithm context must be created using L<EVP_PKEY_CTX_new(3)> or
+variants thereof, see that manual for details.
+
+EVP_PKEY_keygen_init() initializes a public key algorithm context using key
+I<pkey> for a key generation operation.
+
+EVP_PKEY_paramgen_init() is similar to EVP_PKEY_keygen_init() except key
+parameters are generated.
 
-The EVP_PKEY_keygen() function performs a key generation operation, the
-generated key is written to B<ppkey>.
+After initialization, generation parameters may be provided with
+L<EVP_PKEY_CTX_ctrl(3)> or L<EVP_PKEY_CTX_set_params(3)>, or any other
+function described in those manuals.
 
-The functions EVP_PKEY_paramgen_init() and EVP_PKEY_paramgen() are similar
-except parameters are generated.
+EVP_PKEY_gen() performs the generation operation, the resulting key
+parameters or key are written to I<*ppkey>.  If I<*ppkey> is NULL when this
+function is called, it will be allocated, and should be freed by the caller
+when no longer useful, using L<EVP_PKEY_free(3)>.
+
+EVP_PKEY_paramgen() and EVP_PKEY_keygen() do exactly the same thing as
+EVP_PKEY_gen(), after checking that the corresponding EVP_PKEY_paramgen_init()
+or EVP_PKEY_keygen_init() was used to initialize I<ctx>.
+These are older functions that are kept for backward compatibility.
+It is safe to use EVP_PKEY_gen() instead.
 
 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
+to I<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
+with the generation operation. If I<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.
+I<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
@@ -58,6 +87,13 @@ 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".
 
+=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.
+
 =head1 NOTES
 
 After the call to EVP_PKEY_keygen_init() or EVP_PKEY_paramgen_init() algorithm
@@ -82,13 +118,6 @@ 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.
-
 =head1 EXAMPLES
 
 Generate a 2048 bit RSA key:
@@ -168,11 +197,17 @@ L<EVP_PKEY_derive(3)>
 
 =head1 HISTORY
 
-These functions were added in OpenSSL 1.0.0.
+EVP_PKEY_keygen_init(), int EVP_PKEY_paramgen_init(), EVP_PKEY_keygen(),
+EVP_PKEY_paramgen(), EVP_PKEY_gen_cb(), EVP_PKEY_CTX_set_cb(),
+EVP_PKEY_CTX_get_cb(), EVP_PKEY_CTX_get_keygen_info(),
+EVP_PKEY_CTX_set_app_data() and EVP_PKEY_CTX_get_app_data() were added in
+OpenSSL 1.0.0.
+
+EVP_PKEY_gen() was added in OpenSSL 3.0.
 
 =head1 COPYRIGHT
 
-Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2006-2020 The OpenSSL Project Authors. All Rights Reserved.
 
 Licensed under the Apache License 2.0 (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy