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1=pod
2
3=head1 NAME
4
5openssl-dgst,
6dgst - perform digest operations
7
8=head1 SYNOPSIS
9
10B<openssl dgst>
11[B<-I<digest>>]
12[B<-help>]
13[B<-c>]
14[B<-d>]
15[B<-list>]
16[B<-hex>]
17[B<-binary>]
18[B<-r>]
19[B<-out filename>]
20[B<-sign filename>]
21[B<-keyform arg>]
22[B<-passin arg>]
23[B<-verify filename>]
24[B<-prverify filename>]
25[B<-signature filename>]
26[B<-sigopt nm:v>]
27[B<-hmac key>]
28[B<-fips-fingerprint>]
29[B<-rand file...>]
30[B<-engine id>]
31[B<-engine_impl>]
32[B<file...>]
33
34B<openssl> I<digest> [B<...>]
35
36=head1 DESCRIPTION
37
38The digest functions output the message digest of a supplied file or files
39in hexadecimal.  The digest functions also generate and verify digital
40signatures using message digests.
41
42The generic name, B<dgst>, may be used with an option specifying the
43algorithm to be used.
44The default digest is I<sha256>.
45A supported I<digest> name may also be used as the command name.
46To see the list of supported algorithms, use the I<list --digest-commands>
47command.
48
49=head1 OPTIONS
50
51=over 4
52
53=item B<-help>
54
55Print out a usage message.
56
57=item B<-I<digest>>
58
59Specifies name of a supported digest to be used. To see the list of
60supported digests, use the command I<list --digest-commands>.
61
62=item B<-c>
63
64Print out the digest in two digit groups separated by colons, only relevant if
65B<hex> format output is used.
66
67=item B<-d>
68
69Print out BIO debugging information.
70
71=item B<-list>
72
73Prints out a list of supported message digests.
74
75=item B<-hex>
76
77Digest is to be output as a hex dump. This is the default case for a "normal"
78digest as opposed to a digital signature.  See NOTES below for digital
79signatures using B<-hex>.
80
81=item B<-binary>
82
83Output the digest or signature in binary form.
84
85=item B<-r>
86
87Output the digest in the "coreutils" format, including newlines.
88Used by programs like B<sha1sum>.
89
90=item B<-out filename>
91
92Filename to output to, or standard output by default.
93
94=item B<-sign filename>
95
96Digitally sign the digest using the private key in "filename". Note this option
97does not support Ed25519 or Ed448 private keys.
98
99=item B<-keyform arg>
100
101Specifies the key format to sign digest with. The DER, PEM, P12,
102and ENGINE formats are supported.
103
104=item B<-sigopt nm:v>
105
106Pass options to the signature algorithm during sign or verify operations.
107Names and values of these options are algorithm-specific.
108
109=item B<-passin arg>
110
111The private key password source. For more information about the format of B<arg>
112see L<openssl(1)/Pass Phrase Options>.
113
114=item B<-verify filename>
115
116Verify the signature using the public key in "filename".
117The output is either "Verification OK" or "Verification Failure".
118
119=item B<-prverify filename>
120
121Verify the signature using the private key in "filename".
122
123=item B<-signature filename>
124
125The actual signature to verify.
126
127=item B<-hmac key>
128
129Create a hashed MAC using "key".
130
131=item B<-mac alg>
132
133Create MAC (keyed Message Authentication Code). The most popular MAC
134algorithm is HMAC (hash-based MAC), but there are other MAC algorithms
135which are not based on hash, for instance B<gost-mac> algorithm,
136supported by B<ccgost> engine. MAC keys and other options should be set
137via B<-macopt> parameter.
138
139=item B<-macopt nm:v>
140
141Passes options to MAC algorithm, specified by B<-mac> key.
142Following options are supported by both by B<HMAC> and B<gost-mac>:
143
144=over 4
145
146=item B<key:string>
147
148Specifies MAC key as alphanumeric string (use if key contain printable
149characters only). String length must conform to any restrictions of
150the MAC algorithm for example exactly 32 chars for gost-mac.
151
152=item B<hexkey:string>
153
154Specifies MAC key in hexadecimal form (two hex digits per byte).
155Key length must conform to any restrictions of the MAC algorithm
156for example exactly 32 chars for gost-mac.
157
158=back
159
160=item B<-rand file...>
161
162A file or files containing random data used to seed the random number
163generator.
164Multiple files can be specified separated by an OS-dependent character.
165The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
166all others.
167
168=item [B<-writerand file>]
169
170Writes random data to the specified I<file> upon exit.
171This can be used with a subsequent B<-rand> flag.
172
173=item B<-fips-fingerprint>
174
175Compute HMAC using a specific key for certain OpenSSL-FIPS operations.
176
177=item B<-engine id>
178
179Use engine B<id> for operations (including private key storage).
180This engine is not used as source for digest algorithms, unless it is
181also specified in the configuration file or B<-engine_impl> is also
182specified.
183
184=item B<-engine_impl>
185
186When used with the B<-engine> option, it specifies to also use
187engine B<id> for digest operations.
188
189=item B<file...>
190
191File or files to digest. If no files are specified then standard input is
192used.
193
194=back
195
196
197=head1 EXAMPLES
198
199To create a hex-encoded message digest of a file:
200 openssl dgst -md5 -hex file.txt
201
202To sign a file using SHA-256 with binary file output:
203 openssl dgst -sha256 -sign privatekey.pem -out signature.sign file.txt
204
205To verify a signature:
206 openssl dgst -sha256 -verify publickey.pem \
207 -signature signature.sign \
208 file.txt
209
210
211=head1 NOTES
212
213The digest mechanisms that are available will depend on the options
214used when building OpenSSL.
215The B<list digest-commands> command can be used to list them.
216
217New or agile applications should use probably use SHA-256. Other digests,
218particularly SHA-1 and MD5, are still widely used for interoperating
219with existing formats and protocols.
220
221When signing a file, B<dgst> will automatically determine the algorithm
222(RSA, ECC, etc) to use for signing based on the private key's ASN.1 info.
223When verifying signatures, it only handles the RSA, DSA, or ECDSA signature
224itself, not the related data to identify the signer and algorithm used in
225formats such as x.509, CMS, and S/MIME.
226
227A source of random numbers is required for certain signing algorithms, in
228particular ECDSA and DSA.
229
230The signing and verify options should only be used if a single file is
231being signed or verified.
232
233Hex signatures cannot be verified using B<openssl>.  Instead, use "xxd -r"
234or similar program to transform the hex signature into a binary signature
235prior to verification.
236
237=head1 HISTORY
238
239The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
240The FIPS-related options were removed in OpenSSL 1.1.0.
241
242=head1 COPYRIGHT
243
244Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
245
246Licensed under the OpenSSL license (the "License").  You may not use
247this file except in compliance with the License.  You can obtain a copy
248in the file LICENSE in the source distribution or at
249L<https://www.openssl.org/source/license.html>.
250
251=cut
252