EVP_PKEY_keygen_init(3ssl)

1EVP_PKEY_KEYGEN(3)                  OpenSSL                 EVP_PKEY_KEYGEN(3)
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NAME

6       EVP_PKEY_keygen_init, EVP_PKEY_keygen, EVP_PKEY_paramgen_init,
7       EVP_PKEY_paramgen, EVP_PKEY_CTX_set_cb, EVP_PKEY_CTX_get_cb,
8       EVP_PKEY_CTX_get_keygen_info, EVP_PKEY_CTX_set_app_data,
9       EVP_PKEY_CTX_get_app_data, EVP_PKEY_gen_cb, EVP_PKEY_check,
10       EVP_PKEY_public_check, EVP_PKEY_param_check - key and parameter
11       generation and check functions
12

SYNOPSIS

14        #include <openssl/evp.h>
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16        int EVP_PKEY_keygen_init(EVP_PKEY_CTX *ctx);
17        int EVP_PKEY_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
18        int EVP_PKEY_paramgen_init(EVP_PKEY_CTX *ctx);
19        int EVP_PKEY_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey);
20
21        typedef int EVP_PKEY_gen_cb(EVP_PKEY_CTX *ctx);
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23        void EVP_PKEY_CTX_set_cb(EVP_PKEY_CTX *ctx, EVP_PKEY_gen_cb *cb);
24        EVP_PKEY_gen_cb *EVP_PKEY_CTX_get_cb(EVP_PKEY_CTX *ctx);
25
26        int EVP_PKEY_CTX_get_keygen_info(EVP_PKEY_CTX *ctx, int idx);
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28        void EVP_PKEY_CTX_set_app_data(EVP_PKEY_CTX *ctx, void *data);
29        void *EVP_PKEY_CTX_get_app_data(EVP_PKEY_CTX *ctx);
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31        int EVP_PKEY_check(EVP_PKEY_CTX *ctx);
32        int EVP_PKEY_public_check(EVP_PKEY_CTX *ctx);
33        int EVP_PKEY_param_check(EVP_PKEY_CTX *ctx);
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DESCRIPTION

36       The EVP_PKEY_keygen_init() function initializes a public key algorithm
37       context using key pkey for a key generation operation.
38
39       The EVP_PKEY_keygen() function performs a key generation operation, the
40       generated key is written to ppkey.
41
42       The functions EVP_PKEY_paramgen_init() and EVP_PKEY_paramgen() are
43       similar except parameters are generated.
44
45       The function EVP_PKEY_set_cb() sets the key or parameter generation
46       callback to cb. The function EVP_PKEY_CTX_get_cb() returns the key or
47       parameter generation callback.
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49       The function EVP_PKEY_CTX_get_keygen_info() returns parameters
50       associated with the generation operation. If idx is -1 the total number
51       of parameters available is returned. Any non negative value returns the
52       value of that parameter. EVP_PKEY_CTX_gen_keygen_info() with a
53       nonnegative value for idx should only be called within the generation
54       callback.
55
56       If the callback returns 0 then the key generation operation is aborted
57       and an error occurs. This might occur during a time consuming operation
58       where a user clicks on a "cancel" button.
59
60       The functions EVP_PKEY_CTX_set_app_data() and
61       EVP_PKEY_CTX_get_app_data() set and retrieve an opaque pointer. This
62       can be used to set some application defined value which can be
63       retrieved in the callback: for example a handle which is used to update
64       a "progress dialog".
65
66       EVP_PKEY_check() validates the key-pair given by ctx. This function
67       first tries to use customized key check method in EVP_PKEY_METHOD if
68       it's present; otherwise it calls a default one defined in
69       EVP_PKEY_ASN1_METHOD.
70
71       EVP_PKEY_public_check() validates the public component of the key-pair
72       given by ctx.  This function first tries to use customized key check
73       method in EVP_PKEY_METHOD if it's present; otherwise it calls a default
74       one defined in EVP_PKEY_ASN1_METHOD.
75
76       EVP_PKEY_param_check() validates the algorithm parameters of the key-
77       pair given by ctx.  This function first tries to use customized key
78       check method in EVP_PKEY_METHOD if it's present; otherwise it calls a
79       default one defined in EVP_PKEY_ASN1_METHOD.
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NOTES

82       After the call to EVP_PKEY_keygen_init() or EVP_PKEY_paramgen_init()
83       algorithm specific control operations can be performed to set any
84       appropriate parameters for the operation.
85
86       The functions EVP_PKEY_keygen() and EVP_PKEY_paramgen() can be called
87       more than once on the same context if several operations are performed
88       using the same parameters.
89
90       The meaning of the parameters passed to the callback will depend on the
91       algorithm and the specific implementation of the algorithm. Some might
92       not give any useful information at all during key or parameter
93       generation. Others might not even call the callback.
94
95       The operation performed by key or parameter generation depends on the
96       algorithm used. In some cases (e.g. EC with a supplied named curve) the
97       "generation" option merely sets the appropriate fields in an EVP_PKEY
98       structure.
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100       In OpenSSL an EVP_PKEY structure containing a private key also contains
101       the public key components and parameters (if any). An OpenSSL private
102       key is equivalent to what some libraries call a "key pair". A private
103       key can be used in functions which require the use of a public key or
104       parameters.
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RETURN VALUES

107       EVP_PKEY_keygen_init(), EVP_PKEY_paramgen_init(), EVP_PKEY_keygen() and
108       EVP_PKEY_paramgen() return 1 for success and 0 or a negative value for
109       failure.  In particular a return value of -2 indicates the operation is
110       not supported by the public key algorithm.
111
112       EVP_PKEY_check(), EVP_PKEY_public_check() and EVP_PKEY_param_check()
113       return 1 for success or others for failure. They return -2 if the
114       operation is not supported for the specific algorithm.
115

EXAMPLES

117       Generate a 2048 bit RSA key:
118
119        #include <openssl/evp.h>
120        #include <openssl/rsa.h>
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122        EVP_PKEY_CTX *ctx;
123        EVP_PKEY *pkey = NULL;
124
125        ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL);
126        if (!ctx)
127            /* Error occurred */
128        if (EVP_PKEY_keygen_init(ctx) <= 0)
129            /* Error */
130        if (EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, 2048) <= 0)
131            /* Error */
132
133        /* Generate key */
134        if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
135            /* Error */
136
137       Generate a key from a set of parameters:
138
139        #include <openssl/evp.h>
140        #include <openssl/rsa.h>
141
142        EVP_PKEY_CTX *ctx;
143        ENGINE *eng;
144        EVP_PKEY *pkey = NULL, *param;
145
146        /* Assumed param, eng are set up already */
147        ctx = EVP_PKEY_CTX_new(param, eng);
148        if (!ctx)
149            /* Error occurred */
150        if (EVP_PKEY_keygen_init(ctx) <= 0)
151            /* Error */
152
153        /* Generate key */
154        if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
155            /* Error */
156
157       Example of generation callback for OpenSSL public key implementations:
158
159        /* Application data is a BIO to output status to */
160
161        EVP_PKEY_CTX_set_app_data(ctx, status_bio);
162
163        static int genpkey_cb(EVP_PKEY_CTX *ctx)
164        {
165            char c = '*';
166            BIO *b = EVP_PKEY_CTX_get_app_data(ctx);
167            int p = EVP_PKEY_CTX_get_keygen_info(ctx, 0);
168
169            if (p == 0)
170                c = '.';
171            if (p == 1)
172                c = '+';
173            if (p == 2)
174                c = '*';
175            if (p == 3)
176                c = '\n';
177            BIO_write(b, &c, 1);
178            (void)BIO_flush(b);
179            return 1;
180        }
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HISTORY

188       These functions were added in OpenSSL 1.0.0.
189
190       EVP_PKEY_check(), EVP_PKEY_public_check() and EVP_PKEY_param_check()
191       were added in OpenSSL 1.1.1.
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COPYRIGHT

194       Copyright 2006-2020 The OpenSSL Project Authors. All Rights Reserved.
195
196       Licensed under the OpenSSL license (the "License").  You may not use
197       this file except in compliance with the License.  You can obtain a copy
198       in the file LICENSE in the source distribution or at
199       <https://www.openssl.org/source/license.html>.
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2031.1.1q                            2022-07-21                EVP_PKEY_KEYGEN(3)