xref: /openssl/doc/man1/openssl-kdf.pod.in (revision da1c088f)
1=pod
2{- OpenSSL::safe::output_do_not_edit_headers(); -}
3
4=head1 NAME
5
6openssl-kdf - perform Key Derivation Function operations
7
8=head1 SYNOPSIS
9
10B<openssl kdf>
11[B<-help>]
12[B<-cipher>]
13[B<-digest>]
14[B<-mac>]
15[B<-kdfopt> I<nm>:I<v>]
16[B<-keylen> I<num>]
17[B<-out> I<filename>]
18[B<-binary>]
19{- $OpenSSL::safe::opt_provider_synopsis -}
20I<kdf_name>
21
22=head1 DESCRIPTION
23
24The key derivation functions generate a derived key from either a secret or
25password.
26
27=head1 OPTIONS
28
29=over 4
30
31=item B<-help>
32
33Print a usage message.
34
35=item B<-keylen> I<num>
36
37The output size of the derived key. This field is required.
38
39=item B<-out> I<filename>
40
41Filename to output to, or standard output by default.
42
43=item B<-binary>
44
45Output the derived key in binary form. Uses hexadecimal text format if not specified.
46
47=item B<-cipher> I<name>
48
49Specify the cipher to be used by the KDF.
50Not all KDFs require a cipher and it is an error to use this option in such
51cases.
52
53=item B<-digest> I<name>
54
55Specify the digest to be used by the KDF.
56Not all KDFs require a digest and it is an error to use this option in such
57cases.
58To see the list of supported digests, use C<openssl list -digest-commands>.
59
60=item B<-mac> I<name>
61
62Specify the MAC to be used by the KDF.
63Not all KDFs require a MAC and it is an error to use this option in such
64cases.
65
66=item B<-kdfopt> I<nm>:I<v>
67
68Passes options to the KDF algorithm.
69A comprehensive list of parameters can be found in L<EVP_KDF(3)/PARAMETERS>.
70Common parameter names used by EVP_KDF_CTX_set_params() are:
71
72=over 4
73
74=item B<key:>I<string>
75
76Specifies the secret key as an alphanumeric string (use if the key contains
77printable characters only).
78The string length must conform to any restrictions of the KDF algorithm.
79A key must be specified for most KDF algorithms.
80
81=item B<hexkey:>I<string>
82
83Alternative to the B<key:> option where
84the secret key is specified in hexadecimal form (two hex digits per byte).
85
86=item B<pass:>I<string>
87
88Specifies the password as an alphanumeric string (use if the password contains
89printable characters only).
90The password must be specified for PBKDF2 and scrypt.
91
92=item B<hexpass:>I<string>
93
94Alternative to the B<pass:> option where
95the password is specified in hexadecimal form (two hex digits per byte).
96
97=item B<salt:>I<string>
98
99Specifies a non-secret unique cryptographic salt as an alphanumeric string
100(use if it contains printable characters only).
101The length must conform to any restrictions of the KDF algorithm.
102A salt parameter is required for several KDF algorithms,
103such as L<EVP_KDF-PBKDF2(7)>.
104
105=item B<hexsalt:>I<string>
106
107Alternative to the B<salt:> option where
108the salt is specified in hexadecimal form (two hex digits per byte).
109
110=item B<info:>I<string>
111
112Some KDF implementations, such as L<EVP_KDF-HKDF(7)>, take an 'info' parameter
113for binding the derived key material
114to application- and context-specific information.
115Specifies the info, fixed info, other info or shared info argument
116as an alphanumeric string (use if it contains printable characters only).
117The length must conform to any restrictions of the KDF algorithm.
118
119=item B<hexinfo:>I<string>
120
121Alternative to the B<info:> option where
122the info is specified in hexadecimal form (two hex digits per byte).
123
124=item B<digest:>I<string>
125
126This option is identical to the B<-digest> option.
127
128=item B<cipher:>I<string>
129
130This option is identical to the B<-cipher> option.
131
132=item B<mac:>I<string>
133
134This option is identical to the B<-mac> option.
135
136=back
137
138{- $OpenSSL::safe::opt_provider_item -}
139
140=item I<kdf_name>
141
142Specifies the name of a supported KDF algorithm which will be used.
143The supported algorithms names include TLS1-PRF, HKDF, SSKDF, PBKDF2,
144SSHKDF, X942KDF-ASN1, X942KDF-CONCAT, X963KDF and SCRYPT.
145
146=back
147
148=head1 EXAMPLES
149
150Use TLS1-PRF to create a hex-encoded derived key from a secret key and seed:
151
152    openssl kdf -keylen 16 -kdfopt digest:SHA2-256 -kdfopt key:secret \
153                -kdfopt seed:seed TLS1-PRF
154
155Use HKDF to create a hex-encoded derived key from a secret key, salt and info:
156
157    openssl kdf -keylen 10 -kdfopt digest:SHA2-256 -kdfopt key:secret \
158                -kdfopt salt:salt -kdfopt info:label HKDF
159
160Use SSKDF with KMAC to create a hex-encoded derived key from a secret key, salt and info:
161
162    openssl kdf -keylen 64 -kdfopt mac:KMAC-128 -kdfopt maclen:20 \
163                -kdfopt hexkey:b74a149a161545 -kdfopt hexinfo:348a37a2 \
164                -kdfopt hexsalt:3638271ccd68a2 SSKDF
165
166Use SSKDF with HMAC to create a hex-encoded derived key from a secret key, salt and info:
167
168    openssl kdf -keylen 16 -kdfopt mac:HMAC -kdfopt digest:SHA2-256 \
169                -kdfopt hexkey:b74a149a -kdfopt hexinfo:348a37a2 \
170                -kdfopt hexsalt:3638271c SSKDF
171
172Use SSKDF with Hash to create a hex-encoded derived key from a secret key, salt and info:
173
174    openssl kdf -keylen 14 -kdfopt digest:SHA2-256 \
175                -kdfopt hexkey:6dbdc23f045488 \
176                -kdfopt hexinfo:a1b2c3d4 SSKDF
177
178Use SSHKDF to create a hex-encoded derived key from a secret key, hash and session_id:
179
180    openssl kdf -keylen 16 -kdfopt digest:SHA2-256 \
181                -kdfopt hexkey:0102030405 \
182                -kdfopt hexxcghash:06090A \
183                -kdfopt hexsession_id:01020304 \
184                -kdfopt type:A SSHKDF
185
186Use PBKDF2 to create a hex-encoded derived key from a password and salt:
187
188    openssl kdf -keylen 32 -kdfopt digest:SHA256 -kdfopt pass:password \
189                -kdfopt salt:salt -kdfopt iter:2 PBKDF2
190
191Use scrypt to create a hex-encoded derived key from a password and salt:
192
193    openssl kdf -keylen 64 -kdfopt pass:password -kdfopt salt:NaCl \
194                -kdfopt n:1024 -kdfopt r:8 -kdfopt p:16 \
195                -kdfopt maxmem_bytes:10485760 SCRYPT
196
197=head1 NOTES
198
199The KDF mechanisms that are available will depend on the options
200used when building OpenSSL.
201
202=head1 SEE ALSO
203
204L<openssl(1)>,
205L<openssl-pkeyutl(1)>,
206L<EVP_KDF(3)>,
207L<EVP_KDF-SCRYPT(7)>,
208L<EVP_KDF-TLS1_PRF(7)>,
209L<EVP_KDF-PBKDF2(7)>,
210L<EVP_KDF-HKDF(7)>,
211L<EVP_KDF-SS(7)>,
212L<EVP_KDF-SSHKDF(7)>,
213L<EVP_KDF-X942-ASN1(7)>,
214L<EVP_KDF-X942-CONCAT(7)>,
215L<EVP_KDF-X963(7)>
216
217=head1 HISTORY
218
219Added in OpenSSL 3.0
220
221=head1 COPYRIGHT
222
223Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.
224
225Licensed under the Apache License 2.0 (the "License").  You may not use
226this file except in compliance with the License.  You can obtain a copy
227in the file LICENSE in the source distribution or at
228L<https://www.openssl.org/source/license.html>.
229
230=cut
231