dgst.pod revision 273399 
1=pod
2
3=head1 NAME
4
5dgst, sha, sha1, mdc2, ripemd160, sha224, sha256, sha384, sha512, md2, md4, md5, dss1 - message digests
6
7=head1 SYNOPSIS
8
9B<openssl> B<dgst> 
10[B<-sha|-sha1|-mdc2|-ripemd160|-sha224|-sha256|-sha384|-sha512|-md2|-md4|-md5|-dss1>]
11[B<-c>]
12[B<-d>]
13[B<-hex>]
14[B<-binary>]
15[B<-r>]
16[B<-out filename>]
17[B<-sign filename>]
18[B<-keyform arg>]
19[B<-passin arg>]
20[B<-verify filename>]
21[B<-prverify filename>]
22[B<-signature filename>]
23[B<-hmac key>]
24[B<-non-fips-allow>]
25[B<-fips-fingerprint>]
26[B<file...>]
27
28B<openssl>
29[I<digest>]
30[B<...>]
31
32=head1 DESCRIPTION
33
34The digest functions output the message digest of a supplied file or files
35in hexadecimal.  The digest functions also generate and verify digital
36signatures using message digests.
37
38=head1 OPTIONS
39
40=over 4
41
42=item B<-c>
43
44print out the digest in two digit groups separated by colons, only relevant if
45B<hex> format output is used.
46
47=item B<-d>
48
49print out BIO debugging information.
50
51=item B<-hex>
52
53digest is to be output as a hex dump. This is the default case for a "normal"
54digest as opposed to a digital signature.  See NOTES below for digital
55signatures using B<-hex>.
56
57=item B<-binary>
58
59output the digest or signature in binary form.
60
61=item B<-r>
62
63output the digest in the "coreutils" format used by programs like B<sha1sum>.
64
65=item B<-out filename>
66
67filename to output to, or standard output by default.
68
69=item B<-sign filename>
70
71digitally sign the digest using the private key in "filename".
72
73=item B<-keyform arg>
74
75Specifies the key format to sign digest with. The DER, PEM, P12,
76and ENGINE formats are supported.
77
78=item B<-engine id>
79
80Use engine B<id> for operations (including private key storage).
81This engine is not used as source for digest algorithms, unless it is
82also specified in the configuration file.
83
84=item B<-sigopt nm:v>
85
86Pass options to the signature algorithm during sign or verify operations.
87Names and values of these options are algorithm-specific.
88
89
90=item B<-passin arg>
91
92the private key password source. For more information about the format of B<arg>
93see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
94
95=item B<-verify filename>
96
97verify the signature using the public key in "filename".
98The output is either "Verification OK" or "Verification Failure".
99
100=item B<-prverify filename>
101
102verify the signature using the private key in "filename".
103
104=item B<-signature filename>
105
106the actual signature to verify.
107
108=item B<-hmac key>
109
110create a hashed MAC using "key".
111
112=item B<-mac alg>
113
114create MAC (keyed Message Authentication Code). The most popular MAC
115algorithm is HMAC (hash-based MAC), but there are other MAC algorithms
116which are not based on hash, for instance B<gost-mac> algorithm,
117supported by B<ccgost> engine. MAC keys and other options should be set
118via B<-macopt> parameter.
119
120=item B<-macopt nm:v>
121
122Passes options to MAC algorithm, specified by B<-mac> key.
123Following options are supported by both by B<HMAC> and B<gost-mac>:
124
125=over 8
126
127=item B<key:string>
128
129Specifies MAC key as alphnumeric string (use if key contain printable
130characters only). String length must conform to any restrictions of
131the MAC algorithm for example exactly 32 chars for gost-mac.
132
133=item B<hexkey:string>
134
135Specifies MAC key in hexadecimal form (two hex digits per byte).
136Key length must conform to any restrictions of the MAC algorithm
137for example exactly 32 chars for gost-mac.
138
139=back
140
141=item B<-rand file(s)>
142
143a file or files containing random data used to seed the random number
144generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
145Multiple files can be specified separated by a OS-dependent character.
146The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
147all others. 
148
149=item B<-non-fips-allow>
150
151enable use of non-FIPS algorithms such as MD5 even in FIPS mode.
152
153=item B<-fips-fingerprint>
154
155compute HMAC using a specific key
156for certain OpenSSL-FIPS operations.
157
158=item B<file...>
159
160file or files to digest. If no files are specified then standard input is
161used.
162
163=back
164
165
166=head1 EXAMPLES
167
168To create a hex-encoded message digest of a file:
169 openssl dgst -md5 -hex file.txt
170
171To sign a file using SHA-256 with binary file output:
172 openssl dgst -sha256 -sign privatekey.pem -out signature.sign file.txt
173
174To verify a signature:
175 openssl dgst -sha256 -verify publickey.pem \
176 -signature signature.sign \
177 file.txt
178
179
180=head1 NOTES
181
182The digest of choice for all new applications is SHA1. Other digests are
183however still widely used.
184
185When signing a file, B<dgst> will automatically determine the algorithm
186(RSA, ECC, etc) to use for signing based on the private key's ASN.1 info.
187When verifying signatures, it only handles the RSA, DSA, or ECDSA signature
188itself, not the related data to identify the signer and algorithm used in
189formats such as x.509, CMS, and S/MIME.
190
191A source of random numbers is required for certain signing algorithms, in
192particular ECDSA and DSA.
193
194The signing and verify options should only be used if a single file is
195being signed or verified.
196
197Hex signatures cannot be verified using B<openssl>.  Instead, use "xxd -r"
198or similar program to transform the hex signature into a binary signature
199prior to verification.
200
201
202=cut
203