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1=pod
2
3=head1 NAME
4
5EVP_PKEY_CTX_ctrl,
6EVP_PKEY_CTX_ctrl_str,
7EVP_PKEY_CTX_set_signature_md,
8EVP_PKEY_CTX_get_signature_md,
9EVP_PKEY_CTX_set_mac_key,
10EVP_PKEY_CTX_set_rsa_padding,
11EVP_PKEY_CTX_set_rsa_pss_saltlen,
12EVP_PKEY_CTX_set_rsa_keygen_bits,
13EVP_PKEY_CTX_set_rsa_keygen_pubexp,
14EVP_PKEY_CTX_set_dsa_paramgen_bits,
15EVP_PKEY_CTX_set_dh_paramgen_prime_len,
16EVP_PKEY_CTX_set_dh_paramgen_generator,
17EVP_PKEY_CTX_set_dh_pad,
18EVP_PKEY_CTX_set_dh_nid,
19EVP_PKEY_CTX_set_ec_paramgen_curve_nid,
20EVP_PKEY_CTX_set_ec_param_enc - algorithm specific control operations
21
22=head1 SYNOPSIS
23
24 #include <openssl/evp.h>
25
26 int EVP_PKEY_CTX_ctrl(EVP_PKEY_CTX *ctx, int keytype, int optype,
27 int cmd, int p1, void *p2);
28 int EVP_PKEY_CTX_ctrl_str(EVP_PKEY_CTX *ctx, const char *type,
29 const char *value);
30
31 int EVP_PKEY_CTX_set_signature_md(EVP_PKEY_CTX *ctx, const EVP_MD *md);
32 int EVP_PKEY_CTX_get_signature_md(EVP_PKEY_CTX *ctx, const EVP_MD **pmd);
33
34 int EVP_PKEY_CTX_set_mac_key(EVP_PKEY_CTX *ctx, unsigned char *key, int len);
35
36 #include <openssl/rsa.h>
37
38 int EVP_PKEY_CTX_set_rsa_padding(EVP_PKEY_CTX *ctx, int pad);
39 int EVP_PKEY_CTX_set_rsa_pss_saltlen(EVP_PKEY_CTX *ctx, int len);
40 int EVP_PKEY_CTX_set_rsa_keygen_bits(EVP_PKEY_CTX *ctx, int mbits);
41 int EVP_PKEY_CTX_set_rsa_keygen_pubexp(EVP_PKEY_CTX *ctx, BIGNUM *pubexp);
42
43 #include <openssl/dsa.h>
44 int EVP_PKEY_CTX_set_dsa_paramgen_bits(EVP_PKEY_CTX *ctx, int nbits);
45
46 #include <openssl/dh.h>
47 int EVP_PKEY_CTX_set_dh_paramgen_prime_len(EVP_PKEY_CTX *ctx, int len);
48 int EVP_PKEY_CTX_set_dh_paramgen_generator(EVP_PKEY_CTX *ctx, int gen);
49 int EVP_PKEY_CTX_set_dh_pad(EVP_PKEY_CTX *ctx, int pad);
50 int EVP_PKEY_CTX_set_dh_nid(EVP_PKEY_CTX *ctx, int nid);
51
52 #include <openssl/ec.h>
53 int EVP_PKEY_CTX_set_ec_paramgen_curve_nid(EVP_PKEY_CTX *ctx, int nid);
54 int EVP_PKEY_CTX_set_ec_param_enc(EVP_PKEY_CTX *ctx, int param_enc);
55
56=head1 DESCRIPTION
57
58The function EVP_PKEY_CTX_ctrl() sends a control operation to the context
59B<ctx>. The key type used must match B<keytype> if it is not -1. The parameter
60B<optype> is a mask indicating which operations the control can be applied to.
61The control command is indicated in B<cmd> and any additional arguments in
62B<p1> and B<p2>.
63
64For B<cmd> = B<EVP_PKEY_CTRL_SET_MAC_KEY>, B<p1> is the length of the MAC key,
65and B<p2> is MAC key. This is used by Poly1305, SipHash, HMAC and CMAC.
66
67Applications will not normally call EVP_PKEY_CTX_ctrl() directly but will
68instead call one of the algorithm specific macros below.
69
70The function EVP_PKEY_CTX_ctrl_str() allows an application to send an algorithm
71specific control operation to a context B<ctx> in string form. This is
72intended to be used for options specified on the command line or in text
73files. The commands supported are documented in the openssl utility
74command line pages for the option B<-pkeyopt> which is supported by the
75B<pkeyutl>, B<genpkey> and B<req> commands.
76
77All the remaining "functions" are implemented as macros.
78
79The EVP_PKEY_CTX_set_signature_md() macro sets the message digest type used
80in a signature. It can be used in the RSA, DSA and ECDSA algorithms.
81
82The EVP_PKEY_CTX_get_signature_md() macro gets the message digest type used in a
83signature. It can be used in the RSA, DSA and ECDSA algorithms.
84
85Key generation typically involves setting up parameters to be used and
86generating the private and public key data. Some algorithm implementations
87allow private key data to be set explicitly using the EVP_PKEY_CTX_set_mac_key()
88macro. In this case key generation is simply the process of setting up the
89parameters for the key and then setting the raw key data to the value explicitly
90provided by that macro. Normally applications would call
91L<EVP_PKEY_new_raw_private_key(3)> or similar functions instead of this macro.
92
93The EVP_PKEY_CTX_set_mac_key() macro can be used with any of the algorithms
94supported by the L<EVP_PKEY_new_raw_private_key(3)> function.
95
96The macro EVP_PKEY_CTX_set_rsa_padding() sets the RSA padding mode for B<ctx>.
97The B<pad> parameter can take the value RSA_PKCS1_PADDING for PKCS#1 padding,
98RSA_SSLV23_PADDING for SSLv23 padding, RSA_NO_PADDING for no padding,
99RSA_PKCS1_OAEP_PADDING for OAEP padding (encrypt and decrypt only),
100RSA_X931_PADDING for X9.31 padding (signature operations only) and
101RSA_PKCS1_PSS_PADDING (sign and verify only).
102
103Two RSA padding modes behave differently if EVP_PKEY_CTX_set_signature_md()
104is used. If this macro is called for PKCS#1 padding the plaintext buffer is
105an actual digest value and is encapsulated in a DigestInfo structure according
106to PKCS#1 when signing and this structure is expected (and stripped off) when
107verifying. If this control is not used with RSA and PKCS#1 padding then the
108supplied data is used directly and not encapsulated. In the case of X9.31
109padding for RSA the algorithm identifier byte is added or checked and removed
110if this control is called. If it is not called then the first byte of the plaintext
111buffer is expected to be the algorithm identifier byte.
112
113The EVP_PKEY_CTX_set_rsa_pss_saltlen() macro sets the RSA PSS salt length to
114B<len> as its name implies it is only supported for PSS padding. Three special
115values are supported: RSA_PSS_SALTLEN_DIGEST sets the salt length to the
116digest length, RSA_PSS_SALTLEN_MAX sets the salt length to the maximum
117permissible value. When verifying RSA_PSS_SALTLEN_AUTO causes the salt length
118to be automatically determined based on the B<PSS> block structure. If this
119macro is not called maximum salt length is used when signing and auto detection
120when verifying is used by default.
121
122The EVP_PKEY_CTX_set_rsa_keygen_bits() macro sets the RSA key length for
123RSA key generation to B<bits>. If not specified 1024 bits is used.
124
125The EVP_PKEY_CTX_set_rsa_keygen_pubexp() macro sets the public exponent value
126for RSA key generation to B<pubexp> currently it should be an odd integer. The
127B<pubexp> pointer is used internally by this function so it should not be
128modified or free after the call. If this macro is not called then 65537 is used.
129
130The macro EVP_PKEY_CTX_set_dsa_paramgen_bits() sets the number of bits used
131for DSA parameter generation to B<bits>. If not specified 1024 is used.
132
133The macro EVP_PKEY_CTX_set_dh_paramgen_prime_len() sets the length of the DH
134prime parameter B<p> for DH parameter generation. If this macro is not called
135then 1024 is used.
136
137The EVP_PKEY_CTX_set_dh_paramgen_generator() macro sets DH generator to B<gen>
138for DH parameter generation. If not specified 2 is used.
139
140The EVP_PKEY_CTX_set_dh_pad() macro sets the DH padding mode. If B<pad> is
1411 the shared secret is padded with zeroes up to the size of the DH prime B<p>.
142If B<pad> is zero (the default) then no padding is performed.
143
144EVP_PKEY_CTX_set_dh_nid() sets the DH parameters to values corresponding to
145B<nid>. The B<nid> parameter must be B<NID_ffdhe2048>, B<NID_ffdhe3072>,
146B<NID_ffdhe4096>, B<NID_ffdhe6144> or B<NID_ffdhe8192>. This macro can be
147called during parameter or key generation.
148
149The EVP_PKEY_CTX_set_ec_paramgen_curve_nid() sets the EC curve for EC parameter
150generation to B<nid>. For EC parameter generation this macro must be called
151or an error occurs because there is no default curve.
152This function can also be called to set the curve explicitly when
153generating an EC key.
154
155The EVP_PKEY_CTX_set_ec_param_enc() sets the EC parameter encoding to
156B<param_enc> when generating EC parameters or an EC key. The encoding can be
157B<OPENSSL_EC_EXPLICIT_CURVE> for explicit parameters (the default in versions
158of OpenSSL before 1.1.0) or B<OPENSSL_EC_NAMED_CURVE> to use named curve form.
159For maximum compatibility the named curve form should be used. Note: the
160B<OPENSSL_EC_NAMED_CURVE> value was only added to OpenSSL 1.1.0; previous
161versions should use 0 instead.
162
163=head1 RETURN VALUES
164
165EVP_PKEY_CTX_ctrl() and its macros return a positive value for success and 0
166or a negative value for failure. In particular a return value of -2
167indicates the operation is not supported by the public key algorithm.
168
169=head1 SEE ALSO
170
171L<EVP_PKEY_CTX_new(3)>,
172L<EVP_PKEY_encrypt(3)>,
173L<EVP_PKEY_decrypt(3)>,
174L<EVP_PKEY_sign(3)>,
175L<EVP_PKEY_verify(3)>,
176L<EVP_PKEY_verify_recover(3)>,
177L<EVP_PKEY_derive(3)>
178L<EVP_PKEY_keygen(3)>
179
180=head1 HISTORY
181
182These functions were first added to OpenSSL 1.0.0.
183
184=head1 COPYRIGHT
185
186Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
187
188Licensed under the OpenSSL license (the "License"). You may not use
189this file except in compliance with the License. You can obtain a copy
190in the file LICENSE in the source distribution or at
191L<https://www.openssl.org/source/license.html>.
192
193=cut