5 EVP_PKEY_fromdata_init, EVP_PKEY_fromdata, EVP_PKEY_fromdata_settable
6 - functions to create keys and key parameters from user data
10 #include <openssl/evp.h>
12 int EVP_PKEY_fromdata_init(EVP_PKEY_CTX *ctx);
13 int EVP_PKEY_fromdata(EVP_PKEY_CTX *ctx, EVP_PKEY **ppkey, int selection,
15 const OSSL_PARAM *EVP_PKEY_fromdata_settable(EVP_PKEY_CTX *ctx, int selection);
19 The functions described here are used to create new keys from user
20 provided key data, such as I<n>, I<e> and I<d> for a minimal RSA
23 These functions use an B<EVP_PKEY_CTX> context, which should primarily
24 be created with L<EVP_PKEY_CTX_new_from_name(3)> or
25 L<EVP_PKEY_CTX_new_id(3)>.
27 The exact key data that the user can pass depends on the key type.
28 These are passed as an L<OSSL_PARAM(3)> array.
30 EVP_PKEY_fromdata_init() initializes a public key algorithm context
31 for creating a key or key parameters from user data.
33 EVP_PKEY_fromdata() creates the structure to store a key or key parameters,
34 given data from I<params>, I<selection> and a context that's been initialized
35 with EVP_PKEY_fromdata_init(). The result is written to I<*ppkey>.
36 I<selection> is described in L</Selections>.
37 The parameters that can be used for various types of key are as described by the
38 diverse "Common parameters" sections of the
39 L<B<EVP_PKEY-RSA>(7)|EVP_PKEY-RSA(7)/Common RSA parameters>,
40 L<B<EVP_PKEY-DSA>(7)|EVP_PKEY-DSA(7)/Common DSA & DH parameters>,
41 L<B<EVP_PKEY-DH>(7)|EVP_PKEY-DH(7)/Common DH parameters>,
42 L<B<EVP_PKEY-EC>(7)|EVP_PKEY-EC(7)/Common EC parameters>,
43 L<B<EVP_PKEY-ED448>(7)|EVP_PKEY-ED448(7)/Common X25519, X448, ED25519 and ED448 parameters>,
44 L<B<EVP_PKEY-X25519>(7)|EVP_PKEY-X25519(7)/Common X25519, X448, ED25519 and ED448 parameters>,
45 L<B<EVP_PKEY-X448>(7)|EVP_PKEY-X448(7)/Common X25519, X448, ED25519 and ED448 parameters>,
46 and L<B<EVP_PKEY-ED25519>(7)|EVP_PKEY-ED25519(7)/Common X25519, X448, ED25519 and ED448 parameters> pages.
48 =for comment the awful list of links above is made this way so we get nice
49 rendering as a man-page while still getting proper links in HTML
51 EVP_PKEY_fromdata_settable() gets a constant B<OSSL_PARAM> array that describes
52 the settable parameters that can be used with EVP_PKEY_fromdata().
53 I<selection> is described in L</Selections>.
54 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
58 The following constants can be used for I<selection>:
62 =item B<EVP_PKEY_KEY_PARAMETERS>
64 Only key parameters will be selected.
66 =item B<EVP_PKEY_PUBLIC_KEY>
68 Only public key components will be selected. This includes optional key
71 =item B<EVP_PKEY_KEYPAIR>
73 Any keypair components will be selected. This includes the private key,
74 public key and key parameters.
80 These functions only work with key management methods coming from a provider.
81 This is the mirror function to L<EVP_PKEY_todata(3)>.
83 =for comment We may choose to make this available for legacy methods too...
87 EVP_PKEY_fromdata_init() and EVP_PKEY_fromdata() return 1 for success and 0 or
88 a negative value for failure. In particular a return value of -2 indicates the
89 operation is not supported by the public key algorithm.
93 These examples are very terse for the sake of staying on topic, which
94 is the EVP_PKEY_fromdata() set of functions. In real applications,
95 BIGNUMs would be handled and converted to byte arrays with
96 BN_bn2nativepad(), but that's off topic here.
100 TODO Write a set of cookbook documents and link to them.
104 =head2 Creating an RSA keypair using raw key data
106 #include <openssl/evp.h>
109 * These are extremely small to make this example simple. A real
110 * and secure application will not use such small numbers. A real
111 * and secure application is expected to use BIGNUMs, and to build
112 * this array dynamically.
114 unsigned long rsa_n = 0xbc747fc5;
115 unsigned long rsa_e = 0x10001;
116 unsigned long rsa_d = 0x7b133399;
117 OSSL_PARAM params[] = {
118 OSSL_PARAM_ulong("n", &rsa_n),
119 OSSL_PARAM_ulong("e", &rsa_e),
120 OSSL_PARAM_ulong("d", &rsa_d),
126 EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new_from_name(NULL, "RSA", NULL);
127 EVP_PKEY *pkey = NULL;
130 || EVP_PKEY_fromdata_init(ctx) <= 0
131 || EVP_PKEY_fromdata(ctx, &pkey, EVP_PKEY_KEYPAIR, params) <= 0)
134 /* Do what you want with |pkey| */
137 =head2 Creating an ECC keypair using raw key data
139 #include <openssl/evp.h>
140 #include <openssl/param_build.h>
141 #include <openssl/ec.h>
144 * Fixed data to represent the private and public key.
146 const unsigned char priv_data[] = {
147 0xb9, 0x2f, 0x3c, 0xe6, 0x2f, 0xfb, 0x45, 0x68,
148 0x39, 0x96, 0xf0, 0x2a, 0xaf, 0x6c, 0xda, 0xf2,
149 0x89, 0x8a, 0x27, 0xbf, 0x39, 0x9b, 0x7e, 0x54,
150 0x21, 0xc2, 0xa1, 0xe5, 0x36, 0x12, 0x48, 0x5d
152 /* UNCOMPRESSED FORMAT */
153 const unsigned char pub_data[] = {
154 POINT_CONVERSION_UNCOMPRESSED,
155 0xcf, 0x20, 0xfb, 0x9a, 0x1d, 0x11, 0x6c, 0x5e,
156 0x9f, 0xec, 0x38, 0x87, 0x6c, 0x1d, 0x2f, 0x58,
157 0x47, 0xab, 0xa3, 0x9b, 0x79, 0x23, 0xe6, 0xeb,
158 0x94, 0x6f, 0x97, 0xdb, 0xa3, 0x7d, 0xbd, 0xe5,
159 0x26, 0xca, 0x07, 0x17, 0x8d, 0x26, 0x75, 0xff,
160 0xcb, 0x8e, 0xb6, 0x84, 0xd0, 0x24, 0x02, 0x25,
161 0x8f, 0xb9, 0x33, 0x6e, 0xcf, 0x12, 0x16, 0x2f,
162 0x5c, 0xcd, 0x86, 0x71, 0xa8, 0xbf, 0x1a, 0x47
168 EVP_PKEY *pkey = NULL;
170 OSSL_PARAM_BLD *param_bld;
171 OSSL_PARAM *params = NULL;
174 priv = BN_bin2bn(priv_data, sizeof(priv_data), NULL);
176 param_bld = OSSL_PARAM_BLD_new();
177 if (priv != NULL && param_bld != NULL
178 && OSSL_PARAM_BLD_push_utf8_string(param_bld, "group",
180 && OSSL_PARAM_BLD_push_BN(param_bld, "priv", priv)
181 && OSSL_PARAM_BLD_push_octet_string(param_bld, "pub",
182 pub_data, sizeof(pub_data)))
183 params = OSSL_PARAM_BLD_to_param(param_bld);
185 ctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
188 || EVP_PKEY_fromdata_init(ctx) <= 0
189 || EVP_PKEY_fromdata(ctx, &pkey, EVP_PKEY_KEYPAIR, params) <= 0) {
192 /* Do what you want with |pkey| */
196 EVP_PKEY_CTX_free(ctx);
197 OSSL_PARAM_free(params);
198 OSSL_PARAM_BLD_free(param_bld);
204 =head2 Finding out params for an unknown key type
206 #include <openssl/evp.h>
207 #include <openssl/core.h>
209 /* Program expects a key type as first argument */
210 int main(int argc, char *argv[])
212 EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new_from_name(NULL, argv[1], NULL);
213 const OSSL_PARAM *settable_params = NULL;
217 settable_params = EVP_PKEY_fromdata_settable(ctx, EVP_PKEY_KEYPAIR);
218 if (settable_params == NULL)
221 for (; settable_params->key != NULL; settable_params++) {
222 const char *datatype = NULL;
224 switch (settable_params->data_type) {
225 case OSSL_PARAM_INTEGER:
226 datatype = "integer";
228 case OSSL_PARAM_UNSIGNED_INTEGER:
229 datatype = "unsigned integer";
231 case OSSL_PARAM_UTF8_STRING:
232 datatype = "printable string (utf-8 encoding expected)";
234 case OSSL_PARAM_UTF8_PTR:
235 datatype = "printable string pointer (utf-8 encoding expected)";
237 case OSSL_PARAM_OCTET_STRING:
238 datatype = "octet string";
240 case OSSL_PARAM_OCTET_PTR:
241 datatype = "octet string pointer";
244 printf("%s : %s ", settable_params->key, datatype);
245 if (settable_params->data_size == 0)
246 printf("(unlimited size)\n");
248 printf("(maximum size %zu)\n", settable_params->data_size);
252 The descriptor L<OSSL_PARAM(3)> returned by
253 EVP_PKEY_fromdata_settable() may also be used programmatically, for
254 example with L<OSSL_PARAM_allocate_from_text(3)>.
258 L<EVP_PKEY_CTX_new(3)>, L<provider(7)>, L<EVP_PKEY_gettable_params(3)>,
259 L<OSSL_PARAM(3)>, L<EVP_PKEY_todata(3)>,
260 L<EVP_PKEY-RSA(7)>, L<EVP_PKEY-DSA(7)>, L<EVP_PKEY-DH(7)>, L<EVP_PKEY-EC(7)>,
261 L<EVP_PKEY-ED448(7)>, L<EVP_PKEY-X25519(7)>, L<EVP_PKEY-X448(7)>,
262 L<EVP_PKEY-ED25519(7)>
266 These functions were added in OpenSSL 3.0.
270 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
272 Licensed under the Apache License 2.0 (the "License"). You may not use
273 this file except in compliance with the License. You can obtain a copy
274 in the file LICENSE in the source distribution or at
275 L<https://www.openssl.org/source/license.html>.