1=pod
2
3=head1 NAME
4
5EVP_PKEY_CTX_ctrl,
6EVP_PKEY_CTX_ctrl_str,
7EVP_PKEY_CTX_ctrl_uint64,
8EVP_PKEY_CTX_md,
9EVP_PKEY_CTX_set_signature_md,
10EVP_PKEY_CTX_get_signature_md,
11EVP_PKEY_CTX_set_mac_key,
12EVP_PKEY_CTX_set_group_name,
13EVP_PKEY_CTX_get_group_name,
14EVP_PKEY_CTX_set_rsa_padding,
15EVP_PKEY_CTX_get_rsa_padding,
16EVP_PKEY_CTX_set_rsa_pss_saltlen,
17EVP_PKEY_CTX_get_rsa_pss_saltlen,
18EVP_PKEY_CTX_set_rsa_keygen_bits,
19EVP_PKEY_CTX_set_rsa_keygen_pubexp,
20EVP_PKEY_CTX_set1_rsa_keygen_pubexp,
21EVP_PKEY_CTX_set_rsa_keygen_primes,
22EVP_PKEY_CTX_set_rsa_mgf1_md_name,
23EVP_PKEY_CTX_set_rsa_mgf1_md,
24EVP_PKEY_CTX_get_rsa_mgf1_md,
25EVP_PKEY_CTX_get_rsa_mgf1_md_name,
26EVP_PKEY_CTX_set_rsa_oaep_md_name,
27EVP_PKEY_CTX_set_rsa_oaep_md,
28EVP_PKEY_CTX_get_rsa_oaep_md,
29EVP_PKEY_CTX_get_rsa_oaep_md_name,
30EVP_PKEY_CTX_set0_rsa_oaep_label,
31EVP_PKEY_CTX_get0_rsa_oaep_label,
32EVP_PKEY_CTX_set_dsa_paramgen_bits,
33EVP_PKEY_CTX_set_dsa_paramgen_q_bits,
34EVP_PKEY_CTX_set_dsa_paramgen_md,
35EVP_PKEY_CTX_set_dsa_paramgen_md_props,
36EVP_PKEY_CTX_set_dsa_paramgen_gindex,
37EVP_PKEY_CTX_set_dsa_paramgen_type,
38EVP_PKEY_CTX_set_dsa_paramgen_seed,
39EVP_PKEY_CTX_set_dh_paramgen_prime_len,
40EVP_PKEY_CTX_set_dh_paramgen_subprime_len,
41EVP_PKEY_CTX_set_dh_paramgen_generator,
42EVP_PKEY_CTX_set_dh_paramgen_type,
43EVP_PKEY_CTX_set_dh_paramgen_gindex,
44EVP_PKEY_CTX_set_dh_paramgen_seed,
45EVP_PKEY_CTX_set_dh_rfc5114,
46EVP_PKEY_CTX_set_dhx_rfc5114,
47EVP_PKEY_CTX_set_dh_pad,
48EVP_PKEY_CTX_set_dh_nid,
49EVP_PKEY_CTX_set_dh_kdf_type,
50EVP_PKEY_CTX_get_dh_kdf_type,
51EVP_PKEY_CTX_set0_dh_kdf_oid,
52EVP_PKEY_CTX_get0_dh_kdf_oid,
53EVP_PKEY_CTX_set_dh_kdf_md,
54EVP_PKEY_CTX_get_dh_kdf_md,
55EVP_PKEY_CTX_set_dh_kdf_outlen,
56EVP_PKEY_CTX_get_dh_kdf_outlen,
57EVP_PKEY_CTX_set0_dh_kdf_ukm,
58EVP_PKEY_CTX_get0_dh_kdf_ukm,
59EVP_PKEY_CTX_set_ec_paramgen_curve_nid,
60EVP_PKEY_CTX_set_ec_param_enc,
61EVP_PKEY_CTX_set_ecdh_cofactor_mode,
62EVP_PKEY_CTX_get_ecdh_cofactor_mode,
63EVP_PKEY_CTX_set_ecdh_kdf_type,
64EVP_PKEY_CTX_get_ecdh_kdf_type,
65EVP_PKEY_CTX_set_ecdh_kdf_md,
66EVP_PKEY_CTX_get_ecdh_kdf_md,
67EVP_PKEY_CTX_set_ecdh_kdf_outlen,
68EVP_PKEY_CTX_get_ecdh_kdf_outlen,
69EVP_PKEY_CTX_set0_ecdh_kdf_ukm,
70EVP_PKEY_CTX_get0_ecdh_kdf_ukm,
71EVP_PKEY_CTX_set1_id, EVP_PKEY_CTX_get1_id, EVP_PKEY_CTX_get1_id_len,
72EVP_PKEY_CTX_set_kem_op
73- algorithm specific control operations
74
75=head1 SYNOPSIS
76
77 #include <openssl/evp.h>
78
79 int EVP_PKEY_CTX_ctrl(EVP_PKEY_CTX *ctx, int keytype, int optype,
80                       int cmd, int p1, void *p2);
81 int EVP_PKEY_CTX_ctrl_uint64(EVP_PKEY_CTX *ctx, int keytype, int optype,
82                              int cmd, uint64_t value);
83 int EVP_PKEY_CTX_ctrl_str(EVP_PKEY_CTX *ctx, const char *type,
84                           const char *value);
85
86 int EVP_PKEY_CTX_md(EVP_PKEY_CTX *ctx, int optype, int cmd, const char *md);
87
88 int EVP_PKEY_CTX_set_signature_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
89 int EVP_PKEY_CTX_get_signature_md(EVP_PKEY_CTX *ctx, const EVP_MD **pmd);
90
91 int EVP_PKEY_CTX_set_mac_key(EVP_PKEY_CTX *ctx, const unsigned char *key,
92                              int len);
93 int EVP_PKEY_CTX_set_group_name(EVP_PKEY_CTX *ctx, const char *name);
94 int EVP_PKEY_CTX_get_group_name(EVP_PKEY_CTX *ctx, char *name, size_t namelen);
95
96 int EVP_PKEY_CTX_set_kem_op(EVP_PKEY_CTX *ctx, const char *op);
97
98 #include <openssl/rsa.h>
99
100 int EVP_PKEY_CTX_set_rsa_padding(EVP_PKEY_CTX *ctx, int pad);
101 int EVP_PKEY_CTX_get_rsa_padding(EVP_PKEY_CTX *ctx, int *pad);
102 int EVP_PKEY_CTX_set_rsa_pss_saltlen(EVP_PKEY_CTX *ctx, int saltlen);
103 int EVP_PKEY_CTX_get_rsa_pss_saltlen(EVP_PKEY_CTX *ctx, int *saltlen);
104 int EVP_PKEY_CTX_set_rsa_keygen_bits(EVP_PKEY_CTX *ctx, int mbits);
105 int EVP_PKEY_CTX_set1_rsa_keygen_pubexp(EVP_PKEY_CTX *ctx, BIGNUM *pubexp);
106 int EVP_PKEY_CTX_set_rsa_keygen_primes(EVP_PKEY_CTX *ctx, int primes);
107 int EVP_PKEY_CTX_set_rsa_mgf1_md_name(EVP_PKEY_CTX *ctx, const char *mdname,
108                                     const char *mdprops);
109 int EVP_PKEY_CTX_set_rsa_mgf1_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
110 int EVP_PKEY_CTX_get_rsa_mgf1_md(EVP_PKEY_CTX *ctx, const EVP_MD **md);
111 int EVP_PKEY_CTX_get_rsa_mgf1_md_name(EVP_PKEY_CTX *ctx, char *name,
112                                       size_t namelen);
113 int EVP_PKEY_CTX_set_rsa_oaep_md_name(EVP_PKEY_CTX *ctx, const char *mdname,
114                                       const char *mdprops);
115 int EVP_PKEY_CTX_set_rsa_oaep_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
116 int EVP_PKEY_CTX_get_rsa_oaep_md(EVP_PKEY_CTX *ctx, const EVP_MD **md);
117 int EVP_PKEY_CTX_get_rsa_oaep_md_name(EVP_PKEY_CTX *ctx, char *name,
118                                       size_t namelen);
119 int EVP_PKEY_CTX_set0_rsa_oaep_label(EVP_PKEY_CTX *ctx, void *label,
120                                      int len);
121 int EVP_PKEY_CTX_get0_rsa_oaep_label(EVP_PKEY_CTX *ctx, unsigned char **label);
122
123 #include <openssl/dsa.h>
124
125 int EVP_PKEY_CTX_set_dsa_paramgen_bits(EVP_PKEY_CTX *ctx, int nbits);
126 int EVP_PKEY_CTX_set_dsa_paramgen_q_bits(EVP_PKEY_CTX *ctx, int qbits);
127 int EVP_PKEY_CTX_set_dsa_paramgen_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
128 int EVP_PKEY_CTX_set_dsa_paramgen_md_props(EVP_PKEY_CTX *ctx,
129                                            const char *md_name,
130                                            const char *md_properties);
131 int EVP_PKEY_CTX_set_dsa_paramgen_type(EVP_PKEY_CTX *ctx, const char *name);
132 int EVP_PKEY_CTX_set_dsa_paramgen_gindex(EVP_PKEY_CTX *ctx, int gindex);
133 int EVP_PKEY_CTX_set_dsa_paramgen_seed(EVP_PKEY_CTX *ctx,
134                                        const unsigned char *seed,
135                                        size_t seedlen);
136
137 #include <openssl/dh.h>
138
139 int EVP_PKEY_CTX_set_dh_paramgen_prime_len(EVP_PKEY_CTX *ctx, int len);
140 int EVP_PKEY_CTX_set_dh_paramgen_subprime_len(EVP_PKEY_CTX *ctx, int len);
141 int EVP_PKEY_CTX_set_dh_paramgen_generator(EVP_PKEY_CTX *ctx, int gen);
142 int EVP_PKEY_CTX_set_dh_paramgen_type(EVP_PKEY_CTX *ctx, int type);
143 int EVP_PKEY_CTX_set_dh_pad(EVP_PKEY_CTX *ctx, int pad);
144 int EVP_PKEY_CTX_set_dh_nid(EVP_PKEY_CTX *ctx, int nid);
145 int EVP_PKEY_CTX_set_dh_rfc5114(EVP_PKEY_CTX *ctx, int rfc5114);
146 int EVP_PKEY_CTX_set_dhx_rfc5114(EVP_PKEY_CTX *ctx, int rfc5114);
147 int EVP_PKEY_CTX_set_dh_paramgen_gindex(EVP_PKEY_CTX *ctx, int gindex);
148 int EVP_PKEY_CTX_set_dh_paramgen_seed(EVP_PKEY_CTX *ctx,
149                                        const unsigned char *seed,
150                                        size_t seedlen);
151 int EVP_PKEY_CTX_set_dh_kdf_type(EVP_PKEY_CTX *ctx, int kdf);
152 int EVP_PKEY_CTX_get_dh_kdf_type(EVP_PKEY_CTX *ctx);
153 int EVP_PKEY_CTX_set0_dh_kdf_oid(EVP_PKEY_CTX *ctx, ASN1_OBJECT *oid);
154 int EVP_PKEY_CTX_get0_dh_kdf_oid(EVP_PKEY_CTX *ctx, ASN1_OBJECT **oid);
155 int EVP_PKEY_CTX_set_dh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
156 int EVP_PKEY_CTX_get_dh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD **md);
157 int EVP_PKEY_CTX_set_dh_kdf_outlen(EVP_PKEY_CTX *ctx, int len);
158 int EVP_PKEY_CTX_get_dh_kdf_outlen(EVP_PKEY_CTX *ctx, int *len);
159 int EVP_PKEY_CTX_set0_dh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char *ukm, int len);
160
161 #include <openssl/ec.h>
162
163 int EVP_PKEY_CTX_set_ec_paramgen_curve_nid(EVP_PKEY_CTX *ctx, int nid);
164 int EVP_PKEY_CTX_set_ec_param_enc(EVP_PKEY_CTX *ctx, int param_enc);
165 int EVP_PKEY_CTX_set_ecdh_cofactor_mode(EVP_PKEY_CTX *ctx, int cofactor_mode);
166 int EVP_PKEY_CTX_get_ecdh_cofactor_mode(EVP_PKEY_CTX *ctx);
167 int EVP_PKEY_CTX_set_ecdh_kdf_type(EVP_PKEY_CTX *ctx, int kdf);
168 int EVP_PKEY_CTX_get_ecdh_kdf_type(EVP_PKEY_CTX *ctx);
169 int EVP_PKEY_CTX_set_ecdh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
170 int EVP_PKEY_CTX_get_ecdh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD **md);
171 int EVP_PKEY_CTX_set_ecdh_kdf_outlen(EVP_PKEY_CTX *ctx, int len);
172 int EVP_PKEY_CTX_get_ecdh_kdf_outlen(EVP_PKEY_CTX *ctx, int *len);
173 int EVP_PKEY_CTX_set0_ecdh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char *ukm, int len);
174
175 int EVP_PKEY_CTX_set1_id(EVP_PKEY_CTX *ctx, void *id, size_t id_len);
176 int EVP_PKEY_CTX_get1_id(EVP_PKEY_CTX *ctx, void *id);
177 int EVP_PKEY_CTX_get1_id_len(EVP_PKEY_CTX *ctx, size_t *id_len);
178
179The following functions have been deprecated since OpenSSL 3.0, and can be
180hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
181see L<openssl_user_macros(7)>:
182
183 #include <openssl/rsa.h>
184
185 int EVP_PKEY_CTX_set_rsa_keygen_pubexp(EVP_PKEY_CTX *ctx, BIGNUM *pubexp);
186
187 #include <openssl/dh.h>
188
189 int EVP_PKEY_CTX_get0_dh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char **ukm);
190
191 #include <openssl/ec.h>
192
193 int EVP_PKEY_CTX_get0_ecdh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char **ukm);
194
195=head1 DESCRIPTION
196
197EVP_PKEY_CTX_ctrl() sends a control operation to the context I<ctx>. The key
198type used must match I<keytype> if it is not -1. The parameter I<optype> is a
199mask indicating which operations the control can be applied to.
200The control command is indicated in I<cmd> and any additional arguments in
201I<p1> and I<p2>.
202
203For I<cmd> = B<EVP_PKEY_CTRL_SET_MAC_KEY>, I<p1> is the length of the MAC key,
204and I<p2> is the MAC key. This is used by Poly1305, SipHash, HMAC and CMAC.
205
206Applications will not normally call EVP_PKEY_CTX_ctrl() directly but will
207instead call one of the algorithm specific functions below.
208
209EVP_PKEY_CTX_ctrl_uint64() is a wrapper that directly passes a
210uint64 value as I<p2> to EVP_PKEY_CTX_ctrl().
211
212EVP_PKEY_CTX_ctrl_str() allows an application to send an algorithm
213specific control operation to a context I<ctx> in string form. This is
214intended to be used for options specified on the command line or in text
215files. The commands supported are documented in the openssl utility
216command line pages for the option I<-pkeyopt> which is supported by the
217I<pkeyutl>, I<genpkey> and I<req> commands.
218
219EVP_PKEY_CTX_md() sends a message digest control operation to the context
220I<ctx>. The message digest is specified by its name I<md>.
221
222EVP_PKEY_CTX_set_signature_md() sets the message digest type used
223in a signature. It can be used in the RSA, DSA and ECDSA algorithms.
224
225EVP_PKEY_CTX_get_signature_md()gets the message digest type used
226in a signature. It can be used in the RSA, DSA and ECDSA algorithms.
227
228Key generation typically involves setting up parameters to be used and
229generating the private and public key data. Some algorithm implementations
230allow private key data to be set explicitly using EVP_PKEY_CTX_set_mac_key().
231In this case key generation is simply the process of setting up the
232parameters for the key and then setting the raw key data to the value explicitly.
233Normally applications would call L<EVP_PKEY_new_raw_private_key(3)> or similar
234functions instead.
235
236EVP_PKEY_CTX_set_mac_key() can be used with any of the algorithms supported by
237the L<EVP_PKEY_new_raw_private_key(3)> function.
238
239EVP_PKEY_CTX_set_group_name() sets the group name to I<name> for parameter and
240key generation. For example for EC keys this will set the curve name and for
241DH keys it will set the name of the finite field group.
242
243EVP_PKEY_CTX_get_group_name() finds the group name that's currently
244set with I<ctx>, and writes it to the location that I<name> points at, as long
245as its size I<namelen> is large enough to store that name, including a
246terminating NUL byte.
247
248=head2 RSA parameters
249
250EVP_PKEY_CTX_set_rsa_padding() sets the RSA padding mode for I<ctx>.
251The I<pad> parameter can take the value B<RSA_PKCS1_PADDING> for PKCS#1
252padding, B<RSA_NO_PADDING> for
253no padding, B<RSA_PKCS1_OAEP_PADDING> for OAEP padding (encrypt and
254decrypt only), B<RSA_X931_PADDING> for X9.31 padding (signature operations
255only), B<RSA_PKCS1_PSS_PADDING> (sign and verify only) and
256B<RSA_PKCS1_WITH_TLS_PADDING> for TLS RSA ClientKeyExchange message padding
257(decryption only).
258
259Two RSA padding modes behave differently if EVP_PKEY_CTX_set_signature_md()
260is used. If this function is called for PKCS#1 padding the plaintext buffer is
261an actual digest value and is encapsulated in a DigestInfo structure according
262to PKCS#1 when signing and this structure is expected (and stripped off) when
263verifying. If this control is not used with RSA and PKCS#1 padding then the
264supplied data is used directly and not encapsulated. In the case of X9.31
265padding for RSA the algorithm identifier byte is added or checked and removed
266if this control is called. If it is not called then the first byte of the plaintext
267buffer is expected to be the algorithm identifier byte.
268
269EVP_PKEY_CTX_get_rsa_padding() gets the RSA padding mode for I<ctx>.
270
271EVP_PKEY_CTX_set_rsa_pss_saltlen() sets the RSA PSS salt length to I<saltlen>.
272As its name implies it is only supported for PSS padding. If this function is
273not called then the maximum salt length is used when signing and auto detection
274when verifying. Three special values are supported:
275
276=over 4
277
278=item B<RSA_PSS_SALTLEN_DIGEST>
279
280sets the salt length to the digest length.
281
282=item B<RSA_PSS_SALTLEN_MAX>
283
284sets the salt length to the maximum permissible value.
285
286=item B<RSA_PSS_SALTLEN_AUTO>
287
288causes the salt length to be automatically determined based on the
289B<PSS> block structure when verifying.  When signing, it has the same
290meaning as B<RSA_PSS_SALTLEN_MAX>.
291
292=back
293
294EVP_PKEY_CTX_get_rsa_pss_saltlen() gets the RSA PSS salt length for I<ctx>.
295The padding mode must already have been set to B<RSA_PKCS1_PSS_PADDING>.
296
297EVP_PKEY_CTX_set_rsa_keygen_bits() sets the RSA key length for
298RSA key generation to I<bits>. If not specified 2048 bits is used.
299
300EVP_PKEY_CTX_set1_rsa_keygen_pubexp() sets the public exponent value for RSA key
301generation to the value stored in I<pubexp>. Currently it should be an odd
302integer. In accordance with the OpenSSL naming convention, the I<pubexp> pointer
303must be freed independently of the EVP_PKEY_CTX (ie, it is internally copied).
304If not specified 65537 is used.
305
306EVP_PKEY_CTX_set_rsa_keygen_pubexp() does the same as
307EVP_PKEY_CTX_set1_rsa_keygen_pubexp() except that there is no internal copy and
308therefore I<pubexp> should not be modified or freed after the call.
309
310EVP_PKEY_CTX_set_rsa_keygen_primes() sets the number of primes for
311RSA key generation to I<primes>. If not specified 2 is used.
312
313EVP_PKEY_CTX_set_rsa_mgf1_md_name() sets the MGF1 digest for RSA
314padding schemes to the digest named I<mdname>. If the RSA algorithm
315implementation for the selected provider supports it then the digest will be
316fetched using the properties I<mdprops>. If not explicitly set the signing
317digest is used. The padding mode must have been set to B<RSA_PKCS1_OAEP_PADDING>
318or B<RSA_PKCS1_PSS_PADDING>.
319
320EVP_PKEY_CTX_set_rsa_mgf1_md() does the same as
321EVP_PKEY_CTX_set_rsa_mgf1_md_name() except that the name of the digest is
322inferred from the supplied I<md> and it is not possible to specify any
323properties.
324
325EVP_PKEY_CTX_get_rsa_mgf1_md_name() gets the name of the MGF1
326digest algorithm for I<ctx>. If not explicitly set the signing digest is used.
327The padding mode must have been set to B<RSA_PKCS1_OAEP_PADDING> or
328B<RSA_PKCS1_PSS_PADDING>.
329
330EVP_PKEY_CTX_get_rsa_mgf1_md() does the same as
331EVP_PKEY_CTX_get_rsa_mgf1_md_name() except that it returns a pointer to an
332EVP_MD object instead. Note that only known, built-in EVP_MD objects will be
333returned. The EVP_MD object may be NULL if the digest is not one of these (such
334as a digest only implemented in a third party provider).
335
336EVP_PKEY_CTX_set_rsa_oaep_md_name() sets the message digest type
337used in RSA OAEP to the digest named I<mdname>.  If the RSA algorithm
338implementation for the selected provider supports it then the digest will be
339fetched using the properties I<mdprops>. The padding mode must have been set to
340B<RSA_PKCS1_OAEP_PADDING>.
341
342EVP_PKEY_CTX_set_rsa_oaep_md() does the same as
343EVP_PKEY_CTX_set_rsa_oaep_md_name() except that the name of the digest is
344inferred from the supplied I<md> and it is not possible to specify any
345properties.
346
347EVP_PKEY_CTX_get_rsa_oaep_md_name() gets the message digest
348algorithm name used in RSA OAEP and stores it in the buffer I<name> which is of
349size I<namelen>. The padding mode must have been set to
350B<RSA_PKCS1_OAEP_PADDING>. The buffer should be sufficiently large for any
351expected digest algorithm names or the function will fail.
352
353EVP_PKEY_CTX_get_rsa_oaep_md() does the same as
354EVP_PKEY_CTX_get_rsa_oaep_md_name() except that it returns a pointer to an
355EVP_MD object instead. Note that only known, built-in EVP_MD objects will be
356returned. The EVP_MD object may be NULL if the digest is not one of these (such
357as a digest only implemented in a third party provider).
358
359EVP_PKEY_CTX_set0_rsa_oaep_label() sets the RSA OAEP label to binary data
360I<label> and its length in bytes to I<len>. If I<label> is NULL or I<len> is 0,
361the label is cleared. The library takes ownership of the label so the
362caller should not free the original memory pointed to by I<label>.
363The padding mode must have been set to B<RSA_PKCS1_OAEP_PADDING>.
364
365EVP_PKEY_CTX_get0_rsa_oaep_label() gets the RSA OAEP label to
366I<label>. The return value is the label length. The padding mode
367must have been set to B<RSA_PKCS1_OAEP_PADDING>. The resulting pointer is owned
368by the library and should not be freed by the caller.
369
370B<RSA_PKCS1_WITH_TLS_PADDING> is used when decrypting an RSA encrypted TLS
371pre-master secret in a TLS ClientKeyExchange message. It is the same as
372RSA_PKCS1_PADDING except that it additionally verifies that the result is the
373correct length and the first two bytes are the protocol version initially
374requested by the client. If the encrypted content is publicly invalid then the
375decryption will fail. However, if the padding checks fail then decryption will
376still appear to succeed but a random TLS premaster secret will be returned
377instead. This padding mode accepts two parameters which can be set using the
378L<EVP_PKEY_CTX_set_params(3)> function. These are
379OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION and
380OSSL_ASYM_CIPHER_PARAM_TLS_NEGOTIATED_VERSION, both of which are expected to be
381unsigned integers. Normally only the first of these will be set and represents
382the TLS protocol version that was first requested by the client (e.g. 0x0303 for
383TLSv1.2, 0x0302 for TLSv1.1 etc). Historically some buggy clients would use the
384negotiated protocol version instead of the protocol version first requested. If
385this behaviour should be tolerated then
386OSSL_ASYM_CIPHER_PARAM_TLS_NEGOTIATED_VERSION should be set to the actual
387negotiated protocol version. Otherwise it should be left unset.
388
389=head2 DSA parameters
390
391EVP_PKEY_CTX_set_dsa_paramgen_bits() sets the number of bits used for DSA
392parameter generation to B<nbits>. If not specified, 2048 is used.
393
394EVP_PKEY_CTX_set_dsa_paramgen_q_bits() sets the number of bits in the subprime
395parameter I<q> for DSA parameter generation to I<qbits>. If not specified, 224
396is used. If a digest function is specified below, this parameter is ignored and
397instead, the number of bits in I<q> matches the size of the digest.
398
399EVP_PKEY_CTX_set_dsa_paramgen_md() sets the digest function used for DSA
400parameter generation to I<md>. If not specified, one of SHA-1, SHA-224, or
401SHA-256 is selected to match the bit length of I<q> above.
402
403EVP_PKEY_CTX_set_dsa_paramgen_md_props() sets the digest function used for DSA
404parameter generation using I<md_name> and I<md_properties> to retrieve the
405digest from a provider.
406If not specified, I<md_name> will be set to one of SHA-1, SHA-224, or
407SHA-256 depending on the bit length of I<q> above. I<md_properties> is a
408property query string that has a default value of '' if not specified.
409
410EVP_PKEY_CTX_set_dsa_paramgen_gindex() sets the I<gindex> used by the generator
411G. The default value is -1 which uses unverifiable g, otherwise a positive value
412uses verifiable g. This value must be saved if key validation of g is required,
413since it is not part of a persisted key.
414
415EVP_PKEY_CTX_set_dsa_paramgen_seed() sets the I<seed> to use for generation
416rather than using a randomly generated value for the seed. This is useful for
417testing purposes only and can fail if the seed does not produce primes for both
418p & q on its first iteration. This value must be saved if key validation of
419p, q, and verifiable g are required, since it is not part of a persisted key.
420
421EVP_PKEY_CTX_set_dsa_paramgen_type() sets the generation type to use FIPS186-4
422generation if I<name> is "fips186_4", or FIPS186-2 generation if I<name> is
423"fips186_2". The default value for the default provider is "fips186_2". The
424default value for the FIPS provider is "fips186_4".
425
426=head2 DH parameters
427
428EVP_PKEY_CTX_set_dh_paramgen_prime_len() sets the length of the DH prime
429parameter I<p> for DH parameter generation. If this function is not called then
4302048 is used. Only accepts lengths greater than or equal to 256.
431
432EVP_PKEY_CTX_set_dh_paramgen_subprime_len() sets the length of the DH
433optional subprime parameter I<q> for DH parameter generation. The default is
434256 if the prime is at least 2048 bits long or 160 otherwise. The DH paramgen
435type must have been set to "fips186_4".
436
437EVP_PKEY_CTX_set_dh_paramgen_generator() sets DH generator to I<gen> for DH
438parameter generation. If not specified 2 is used.
439
440EVP_PKEY_CTX_set_dh_paramgen_type() sets the key type for DH parameter
441generation. The supported parameters are:
442
443=over 4
444
445=item B<DH_PARAMGEN_TYPE_GROUP>
446
447Use a named group. If only the safe prime parameter I<p> is set this can be
448used to select a ffdhe safe prime group of the correct size.
449
450=item B<DH_PARAMGEN_TYPE_FIPS_186_4>
451
452FIPS186-4 FFC parameter generator.
453
454=item B<DH_PARAMGEN_TYPE_FIPS_186_2>
455
456FIPS186-2 FFC parameter generator (X9.42 DH).
457
458=item B<DH_PARAMGEN_TYPE_GENERATOR>
459
460Uses a safe prime generator g (PKCS#3 format).
461
462=back
463
464The default in the default provider is B<DH_PARAMGEN_TYPE_GENERATOR> for the
465"DH" keytype, and B<DH_PARAMGEN_TYPE_FIPS_186_2> for the "DHX" keytype. In the
466FIPS provider the default value is B<DH_PARAMGEN_TYPE_GROUP> for the "DH"
467keytype and <B<DH_PARAMGEN_TYPE_FIPS_186_4> for the "DHX" keytype.
468
469EVP_PKEY_CTX_set_dh_paramgen_gindex() sets the I<gindex> used by the generator G.
470The default value is -1 which uses unverifiable g, otherwise a positive value
471uses verifiable g. This value must be saved if key validation of g is required,
472since it is not part of a persisted key.
473
474EVP_PKEY_CTX_set_dh_paramgen_seed() sets the I<seed> to use for generation
475rather than using a randomly generated value for the seed. This is useful for
476testing purposes only and can fail if the seed does not produce primes for both
477p & q on its first iteration. This value must be saved if key validation of p, q,
478and verifiable g are required, since it is not part of a persisted key.
479
480EVP_PKEY_CTX_set_dh_pad() sets the DH padding mode.
481If I<pad> is 1 the shared secret is padded with zeros up to the size of the DH
482prime I<p>.
483If I<pad> is zero (the default) then no padding is performed.
484
485EVP_PKEY_CTX_set_dh_nid() sets the DH parameters to values corresponding to
486I<nid> as defined in RFC7919 or RFC3526. The I<nid> parameter must be
487B<NID_ffdhe2048>, B<NID_ffdhe3072>, B<NID_ffdhe4096>, B<NID_ffdhe6144>,
488B<NID_ffdhe8192>, B<NID_modp_1536>, B<NID_modp_2048>, B<NID_modp_3072>,
489B<NID_modp_4096>, B<NID_modp_6144>, B<NID_modp_8192> or B<NID_undef> to clear
490the stored value. This function can be called during parameter or key generation.
491The nid parameter and the rfc5114 parameter are mutually exclusive.
492
493EVP_PKEY_CTX_set_dh_rfc5114() and EVP_PKEY_CTX_set_dhx_rfc5114() both set the
494DH parameters to the values defined in RFC5114. The I<rfc5114> parameter must
495be 1, 2 or 3 corresponding to RFC5114 sections 2.1, 2.2 and 2.3. or 0 to clear
496the stored value. This macro can be called during parameter generation. The
497I<ctx> must have a key type of B<EVP_PKEY_DHX>.
498The rfc5114 parameter and the nid parameter are mutually exclusive.
499
500=head2 DH key derivation function parameters
501
502Note that all of the following functions require that the I<ctx> parameter has
503a private key type of B<EVP_PKEY_DHX>. When using key derivation, the output of
504EVP_PKEY_derive() is the output of the KDF instead of the DH shared secret.
505The KDF output is typically used as a Key Encryption Key (KEK) that in turn
506encrypts a Content Encryption Key (CEK).
507
508EVP_PKEY_CTX_set_dh_kdf_type() sets the key derivation function type to I<kdf>
509for DH key derivation. Possible values are B<EVP_PKEY_DH_KDF_NONE> and
510B<EVP_PKEY_DH_KDF_X9_42> which uses the key derivation specified in RFC2631
511(based on the keying algorithm described in X9.42). When using key derivation,
512the I<kdf_oid>, I<kdf_md> and I<kdf_outlen> parameters must also be specified.
513
514EVP_PKEY_CTX_get_dh_kdf_type() gets the key derivation function type for I<ctx>
515used for DH key derivation. Possible values are B<EVP_PKEY_DH_KDF_NONE> and
516B<EVP_PKEY_DH_KDF_X9_42>.
517
518EVP_PKEY_CTX_set0_dh_kdf_oid() sets the key derivation function object
519identifier to I<oid> for DH key derivation. This OID should identify the
520algorithm to be used with the Content Encryption Key.
521The library takes ownership of the object identifier so the caller should not
522free the original memory pointed to by I<oid>.
523
524EVP_PKEY_CTX_get0_dh_kdf_oid() gets the key derivation function oid for I<ctx>
525used for DH key derivation. The resulting pointer is owned by the library and
526should not be freed by the caller.
527
528EVP_PKEY_CTX_set_dh_kdf_md() sets the key derivation function message digest to
529I<md> for DH key derivation. Note that RFC2631 specifies that this digest should
530be SHA1 but OpenSSL tolerates other digests.
531
532EVP_PKEY_CTX_get_dh_kdf_md() gets the key derivation function message digest for
533I<ctx> used for DH key derivation.
534
535EVP_PKEY_CTX_set_dh_kdf_outlen() sets the key derivation function output length
536to I<len> for DH key derivation.
537
538EVP_PKEY_CTX_get_dh_kdf_outlen() gets the key derivation function output length
539for I<ctx> used for DH key derivation.
540
541EVP_PKEY_CTX_set0_dh_kdf_ukm() sets the user key material to I<ukm> and its
542length to I<len> for DH key derivation. This parameter is optional and
543corresponds to the partyAInfo field in RFC2631 terms. The specification
544requires that it is 512 bits long but this is not enforced by OpenSSL.
545The library takes ownership of the user key material so the caller should not
546free the original memory pointed to by I<ukm>.
547
548EVP_PKEY_CTX_get0_dh_kdf_ukm() gets the user key material for I<ctx>.
549The return value is the user key material length. The resulting pointer is owned
550by the library and should not be freed by the caller.
551
552=head2 EC parameters
553
554Use EVP_PKEY_CTX_set_group_name() (described above) to set the curve name to
555I<name> for parameter and key generation.
556
557EVP_PKEY_CTX_set_ec_paramgen_curve_nid() does the same as
558EVP_PKEY_CTX_set_group_name(), but is specific to EC and uses a I<nid> rather
559than a name string.
560
561For EC parameter generation, one of EVP_PKEY_CTX_set_group_name()
562or EVP_PKEY_CTX_set_ec_paramgen_curve_nid() must be called or an error occurs
563because there is no default curve.
564These function can also be called to set the curve explicitly when
565generating an EC key.
566
567EVP_PKEY_CTX_get_group_name() (described above) can be used to obtain the curve
568name that's currently set with I<ctx>.
569
570EVP_PKEY_CTX_set_ec_param_enc() sets the EC parameter encoding to I<param_enc>
571when generating EC parameters or an EC key. The encoding can be
572B<OPENSSL_EC_EXPLICIT_CURVE> for explicit parameters (the default in versions
573of OpenSSL before 1.1.0) or B<OPENSSL_EC_NAMED_CURVE> to use named curve form.
574For maximum compatibility the named curve form should be used. Note: the
575B<OPENSSL_EC_NAMED_CURVE> value was added in OpenSSL 1.1.0; previous
576versions should use 0 instead.
577
578=head2 ECDH parameters
579
580EVP_PKEY_CTX_set_ecdh_cofactor_mode() sets the cofactor mode to I<cofactor_mode>
581for ECDH key derivation. Possible values are 1 to enable cofactor
582key derivation, 0 to disable it and -1 to clear the stored cofactor mode and
583fallback to the private key cofactor mode.
584
585EVP_PKEY_CTX_get_ecdh_cofactor_mode() returns the cofactor mode for I<ctx> used
586for ECDH key derivation. Possible values are 1 when cofactor key derivation is
587enabled and 0 otherwise.
588
589=head2 ECDH key derivation function parameters
590
591EVP_PKEY_CTX_set_ecdh_kdf_type() sets the key derivation function type to
592I<kdf> for ECDH key derivation. Possible values are B<EVP_PKEY_ECDH_KDF_NONE>
593and B<EVP_PKEY_ECDH_KDF_X9_63> which uses the key derivation specified in X9.63.
594When using key derivation, the I<kdf_md> and I<kdf_outlen> parameters must
595also be specified.
596
597EVP_PKEY_CTX_get_ecdh_kdf_type() returns the key derivation function type for
598I<ctx> used for ECDH key derivation. Possible values are
599B<EVP_PKEY_ECDH_KDF_NONE> and B<EVP_PKEY_ECDH_KDF_X9_63>.
600
601EVP_PKEY_CTX_set_ecdh_kdf_md() sets the key derivation function message digest
602to I<md> for ECDH key derivation. Note that X9.63 specifies that this digest
603should be SHA1 but OpenSSL tolerates other digests.
604
605EVP_PKEY_CTX_get_ecdh_kdf_md() gets the key derivation function message digest
606for I<ctx> used for ECDH key derivation.
607
608EVP_PKEY_CTX_set_ecdh_kdf_outlen() sets the key derivation function output
609length to I<len> for ECDH key derivation.
610
611EVP_PKEY_CTX_get_ecdh_kdf_outlen() gets the key derivation function output
612length for I<ctx> used for ECDH key derivation.
613
614EVP_PKEY_CTX_set0_ecdh_kdf_ukm() sets the user key material to I<ukm> for ECDH
615key derivation. This parameter is optional and corresponds to the shared info in
616X9.63 terms. The library takes ownership of the user key material so the caller
617should not free the original memory pointed to by I<ukm>.
618
619EVP_PKEY_CTX_get0_ecdh_kdf_ukm() gets the user key material for I<ctx>.
620The return value is the user key material length. The resulting pointer is owned
621by the library and should not be freed by the caller.
622
623=head2 Other parameters
624
625EVP_PKEY_CTX_set1_id(), EVP_PKEY_CTX_get1_id() and EVP_PKEY_CTX_get1_id_len()
626are used to manipulate the special identifier field for specific signature
627algorithms such as SM2. The EVP_PKEY_CTX_set1_id() sets an ID pointed by I<id> with
628the length I<id_len> to the library. The library takes a copy of the id so that
629the caller can safely free the original memory pointed to by I<id>.
630EVP_PKEY_CTX_get1_id_len() returns the length of the ID set via a previous call
631to EVP_PKEY_CTX_set1_id(). The length is usually used to allocate adequate
632memory for further calls to EVP_PKEY_CTX_get1_id(). EVP_PKEY_CTX_get1_id()
633returns the previously set ID value to caller in I<id>. The caller should
634allocate adequate memory space for the I<id> before calling EVP_PKEY_CTX_get1_id().
635
636EVP_PKEY_CTX_set_kem_op() sets the KEM operation to run. This can be set after
637EVP_PKEY_encapsulate_init() or EVP_PKEY_decapsulate_init() to select the
638kem operation. RSA is the only key type that supports encapsulation currently,
639and as there is no default operation for the RSA type, this function must be
640called before EVP_PKEY_encapsulate() or EVP_PKEY_decapsulate().
641
642=head1 RETURN VALUES
643
644All other functions described on this page return a positive value for success
645and 0 or a negative value for failure. In particular a return value of -2
646indicates the operation is not supported by the public key algorithm.
647
648=head1 SEE ALSO
649
650L<EVP_PKEY_CTX_set_params(3)>,
651L<EVP_PKEY_CTX_new(3)>,
652L<EVP_PKEY_encrypt(3)>,
653L<EVP_PKEY_decrypt(3)>,
654L<EVP_PKEY_sign(3)>,
655L<EVP_PKEY_verify(3)>,
656L<EVP_PKEY_verify_recover(3)>,
657L<EVP_PKEY_derive(3)>,
658L<EVP_PKEY_keygen(3)>
659L<EVP_PKEY_encapsulate(3)>
660L<EVP_PKEY_decapsulate(3)>
661
662=head1 HISTORY
663
664EVP_PKEY_CTX_get_rsa_oaep_md_name(), EVP_PKEY_CTX_get_rsa_mgf1_md_name(),
665EVP_PKEY_CTX_set_rsa_mgf1_md_name(), EVP_PKEY_CTX_set_rsa_oaep_md_name(),
666EVP_PKEY_CTX_set_dsa_paramgen_md_props(), EVP_PKEY_CTX_set_dsa_paramgen_gindex(),
667EVP_PKEY_CTX_set_dsa_paramgen_type(), EVP_PKEY_CTX_set_dsa_paramgen_seed(),
668EVP_PKEY_CTX_set_group_name() and EVP_PKEY_CTX_get_group_name()
669were added in OpenSSL 3.0.
670
671The EVP_PKEY_CTX_set1_id(), EVP_PKEY_CTX_get1_id() and
672EVP_PKEY_CTX_get1_id_len() macros were added in 1.1.1, other functions were
673added in OpenSSL 1.0.0.
674
675In OpenSSL 1.1.1 and below the functions were mostly macros.
676From OpenSSL 3.0 they are all functions.
677
678EVP_PKEY_CTX_set_rsa_keygen_pubexp(), EVP_PKEY_CTX_get0_dh_kdf_ukm(),
679and EVP_PKEY_CTX_get0_ecdh_kdf_ukm() were deprecated in OpenSSL 3.0.
680
681=head1 COPYRIGHT
682
683Copyright 2006-2021 The OpenSSL Project Authors. All Rights Reserved.
684
685Licensed under the Apache License 2.0 (the "License").  You may not use
686this file except in compliance with the License.  You can obtain a copy
687in the file LICENSE in the source distribution or at
688L<https://www.openssl.org/source/license.html>.
689
690=cut
691