dgst.pod revision 325337 
1=pod
2
3=head1 NAME
4
5openssl-dgst,
6dgst, sha, sha1, mdc2, ripemd160, sha224, sha256, sha384, sha512, md2, md4, md5, dss1 - message digests
7
8=head1 SYNOPSIS
9
10B<openssl> B<dgst> 
11[B<-sha|-sha1|-mdc2|-ripemd160|-sha224|-sha256|-sha384|-sha512|-md2|-md4|-md5|-dss1>]
12[B<-c>]
13[B<-d>]
14[B<-hex>]
15[B<-binary>]
16[B<-r>]
17[B<-non-fips-allow>]
18[B<-out filename>]
19[B<-sign filename>]
20[B<-keyform arg>]
21[B<-passin arg>]
22[B<-verify filename>]
23[B<-prverify filename>]
24[B<-signature filename>]
25[B<-hmac key>]
26[B<-non-fips-allow>]
27[B<-fips-fingerprint>]
28[B<file...>]
29
30B<openssl>
31[I<digest>]
32[B<...>]
33
34=head1 DESCRIPTION
35
36The digest functions output the message digest of a supplied file or files
37in hexadecimal.  The digest functions also generate and verify digital
38signatures using message digests.
39
40=head1 OPTIONS
41
42=over 4
43
44=item B<-c>
45
46print out the digest in two digit groups separated by colons, only relevant if
47B<hex> format output is used.
48
49=item B<-d>
50
51print out BIO debugging information.
52
53=item B<-hex>
54
55digest is to be output as a hex dump. This is the default case for a "normal"
56digest as opposed to a digital signature.  See NOTES below for digital
57signatures using B<-hex>.
58
59=item B<-binary>
60
61output the digest or signature in binary form.
62
63=item B<-r>
64
65output the digest in the "coreutils" format used by programs like B<sha1sum>.
66
67=item B<-non-fips-allow>
68
69Allow use of non FIPS digest when in FIPS mode.  This has no effect when not in
70FIPS mode.
71
72=item B<-out filename>
73
74filename to output to, or standard output by default.
75
76=item B<-sign filename>
77
78digitally sign the digest using the private key in "filename".
79
80=item B<-keyform arg>
81
82Specifies the key format to sign digest with. The DER, PEM, P12,
83and ENGINE formats are supported.
84
85=item B<-engine id>
86
87Use engine B<id> for operations (including private key storage).
88This engine is not used as source for digest algorithms, unless it is
89also specified in the configuration file.
90
91=item B<-sigopt nm:v>
92
93Pass options to the signature algorithm during sign or verify operations.
94Names and values of these options are algorithm-specific.
95
96
97=item B<-passin arg>
98
99the private key password source. For more information about the format of B<arg>
100see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
101
102=item B<-verify filename>
103
104verify the signature using the public key in "filename".
105The output is either "Verification OK" or "Verification Failure".
106
107=item B<-prverify filename>
108
109verify the signature using the private key in "filename".
110
111=item B<-signature filename>
112
113the actual signature to verify.
114
115=item B<-hmac key>
116
117create a hashed MAC using "key".
118
119=item B<-mac alg>
120
121create MAC (keyed Message Authentication Code). The most popular MAC
122algorithm is HMAC (hash-based MAC), but there are other MAC algorithms
123which are not based on hash, for instance B<gost-mac> algorithm,
124supported by B<ccgost> engine. MAC keys and other options should be set
125via B<-macopt> parameter.
126
127=item B<-macopt nm:v>
128
129Passes options to MAC algorithm, specified by B<-mac> key.
130Following options are supported by both by B<HMAC> and B<gost-mac>:
131
132=over 8
133
134=item B<key:string>
135
136Specifies MAC key as alphnumeric string (use if key contain printable
137characters only). String length must conform to any restrictions of
138the MAC algorithm for example exactly 32 chars for gost-mac.
139
140=item B<hexkey:string>
141
142Specifies MAC key in hexadecimal form (two hex digits per byte).
143Key length must conform to any restrictions of the MAC algorithm
144for example exactly 32 chars for gost-mac.
145
146=back
147
148=item B<-rand file(s)>
149
150a file or files containing random data used to seed the random number
151generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
152Multiple files can be specified separated by a OS-dependent character.
153The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
154all others. 
155
156=item B<-non-fips-allow>
157
158enable use of non-FIPS algorithms such as MD5 even in FIPS mode.
159
160=item B<-fips-fingerprint>
161
162compute HMAC using a specific key
163for certain OpenSSL-FIPS operations.
164
165=item B<file...>
166
167file or files to digest. If no files are specified then standard input is
168used.
169
170=back
171
172
173=head1 EXAMPLES
174
175To create a hex-encoded message digest of a file:
176 openssl dgst -md5 -hex file.txt
177
178To sign a file using SHA-256 with binary file output:
179 openssl dgst -sha256 -sign privatekey.pem -out signature.sign file.txt
180
181To verify a signature:
182 openssl dgst -sha256 -verify publickey.pem \
183 -signature signature.sign \
184 file.txt
185
186
187=head1 NOTES
188
189The digest of choice for all new applications is SHA1. Other digests are
190however still widely used.
191
192When signing a file, B<dgst> will automatically determine the algorithm
193(RSA, ECC, etc) to use for signing based on the private key's ASN.1 info.
194When verifying signatures, it only handles the RSA, DSA, or ECDSA signature
195itself, not the related data to identify the signer and algorithm used in
196formats such as x.509, CMS, and S/MIME.
197
198A source of random numbers is required for certain signing algorithms, in
199particular ECDSA and DSA.
200
201The signing and verify options should only be used if a single file is
202being signed or verified.
203
204Hex signatures cannot be verified using B<openssl>.  Instead, use "xxd -r"
205or similar program to transform the hex signature into a binary signature
206prior to verification.
207
208
209=cut
210