pkeyutl.pod revision 325337 
1=pod
2
3=head1 NAME
4
5openssl-pkeyutl,
6pkeyutl - public key algorithm utility
7
8=head1 SYNOPSIS
9
10B<openssl> B<pkeyutl>
11[B<-in file>]
12[B<-out file>]
13[B<-sigfile file>]
14[B<-inkey file>]
15[B<-keyform PEM|DER>]
16[B<-passin arg>]
17[B<-peerkey file>]
18[B<-peerform PEM|DER>]
19[B<-pubin>]
20[B<-certin>]
21[B<-rev>]
22[B<-sign>]
23[B<-verify>]
24[B<-verifyrecover>]
25[B<-encrypt>]
26[B<-decrypt>]
27[B<-derive>]
28[B<-pkeyopt opt:value>]
29[B<-hexdump>]
30[B<-asn1parse>]
31[B<-engine id>]
32
33=head1 DESCRIPTION
34
35The B<pkeyutl> command can be used to perform public key operations using
36any supported algorithm.
37
38=head1 COMMAND OPTIONS
39
40=over 4
41
42=item B<-in filename>
43
44This specifies the input filename to read data from or standard input
45if this option is not specified.
46
47=item B<-out filename>
48
49specifies the output filename to write to or standard output by
50default.
51
52=item B<-inkey file>
53
54the input key file, by default it should be a private key.
55
56=item B<-keyform PEM|DER>
57
58the key format PEM, DER or ENGINE.
59
60=item B<-passin arg>
61
62the input key password source. For more information about the format of B<arg>
63see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
64
65
66=item B<-peerkey file>
67
68the peer key file, used by key derivation (agreement) operations.
69
70=item B<-peerform PEM|DER>
71
72the peer key format PEM, DER or ENGINE.
73
74=item B<-engine id>
75
76specifying an engine (by its unique B<id> string) will cause B<pkeyutl>
77to attempt to obtain a functional reference to the specified engine,
78thus initialising it if needed. The engine will then be set as the default
79for all available algorithms.
80
81
82=item B<-pubin>
83
84the input file is a public key. 
85
86=item B<-certin>
87
88the input is a certificate containing a public key. 
89
90=item B<-rev>
91
92reverse the order of the input buffer. This is useful for some libraries
93(such as CryptoAPI) which represent the buffer in little endian format.
94
95=item B<-sign>
96
97sign the input data and output the signed result. This requires
98a private key.
99
100=item B<-verify>
101
102verify the input data against the signature file and indicate if the
103verification succeeded or failed.
104
105=item B<-verifyrecover>
106
107verify the input data and output the recovered data.
108
109=item B<-encrypt>
110
111encrypt the input data using a public key.
112
113=item B<-decrypt>
114
115decrypt the input data using a private key.
116
117=item B<-derive>
118
119derive a shared secret using the peer key.
120
121=item B<-hexdump>
122
123hex dump the output data.
124
125=item B<-asn1parse>
126
127asn1parse the output data, this is useful when combined with the
128B<-verifyrecover> option when an ASN1 structure is signed.
129
130=back
131
132=head1 NOTES
133
134The operations and options supported vary according to the key algorithm
135and its implementation. The OpenSSL operations and options are indicated below.
136
137Unless otherwise mentioned all algorithms support the B<digest:alg> option
138which specifies the digest in use for sign, verify and verifyrecover operations.
139The value B<alg> should represent a digest name as used in the
140EVP_get_digestbyname() function for example B<sha1>.
141This value is used only for sanity-checking the lengths of data passed in to
142the B<pkeyutl> and for creating the structures that make up the signature
143(e.g. B<DigestInfo> in RSASSA PKCS#1 v1.5 signatures).
144In case of RSA, ECDSA and DSA signatures, this utility
145will not perform hashing on input data but rather use the data directly as
146input of signature algorithm. Depending on key type, signature type and mode
147of padding, the maximum acceptable lengths of input data differ. In general,
148with RSA the signed data can't be longer than the key modulus, in case of ECDSA
149and DSA the data shouldn't be longer than field size, otherwise it will be
150silently truncated to field size.
151
152In other words, if the value of digest is B<sha1> the input should be 20 bytes
153long binary encoding of SHA-1 hash function output.
154
155=head1 RSA ALGORITHM
156
157The RSA algorithm supports encrypt, decrypt, sign, verify and verifyrecover
158operations in general. Some padding modes only support some of these 
159operations however.
160
161=over 4
162
163=item -B<rsa_padding_mode:mode>
164
165This sets the RSA padding mode. Acceptable values for B<mode> are B<pkcs1> for
166PKCS#1 padding, B<sslv23> for SSLv23 padding, B<none> for no padding, B<oaep>
167for B<OAEP> mode, B<x931> for X9.31 mode and B<pss> for PSS.
168
169In PKCS#1 padding if the message digest is not set then the supplied data is 
170signed or verified directly instead of using a B<DigestInfo> structure. If a
171digest is set then the a B<DigestInfo> structure is used and its the length
172must correspond to the digest type.
173
174For B<oeap> mode only encryption and decryption is supported.
175
176For B<x931> if the digest type is set it is used to format the block data
177otherwise the first byte is used to specify the X9.31 digest ID. Sign,
178verify and verifyrecover are can be performed in this mode.
179
180For B<pss> mode only sign and verify are supported and the digest type must be
181specified.
182
183=item B<rsa_pss_saltlen:len>
184
185For B<pss> mode only this option specifies the salt length. Two special values
186are supported: -1 sets the salt length to the digest length. When signing -2
187sets the salt length to the maximum permissible value. When verifying -2 causes
188the salt length to be automatically determined based on the B<PSS> block
189structure.
190
191=back
192
193=head1 DSA ALGORITHM
194
195The DSA algorithm supports signing and verification operations only. Currently
196there are no additional options other than B<digest>. Only the SHA1
197digest can be used and this digest is assumed by default.
198
199=head1 DH ALGORITHM
200
201The DH algorithm only supports the derivation operation and no additional
202options.
203
204=head1 EC ALGORITHM
205
206The EC algorithm supports sign, verify and derive operations. The sign and
207verify operations use ECDSA and derive uses ECDH. Currently there are no
208additional options other than B<digest>. Only the SHA1 digest can be used and
209this digest is assumed by default.
210
211=head1 EXAMPLES
212
213Sign some data using a private key:
214
215 openssl pkeyutl -sign -in file -inkey key.pem -out sig
216
217Recover the signed data (e.g. if an RSA key is used):
218
219 openssl pkeyutl -verifyrecover -in sig -inkey key.pem
220
221Verify the signature (e.g. a DSA key):
222
223 openssl pkeyutl -verify -in file -sigfile sig -inkey key.pem
224
225Sign data using a message digest value (this is currently only valid for RSA):
226
227 openssl pkeyutl -sign -in file -inkey key.pem -out sig -pkeyopt digest:sha256
228
229Derive a shared secret value:
230
231 openssl pkeyutl -derive -inkey key.pem -peerkey pubkey.pem -out secret
232
233=head1 SEE ALSO
234
235L<genpkey(1)|genpkey(1)>, L<pkey(1)|pkey(1)>, L<rsautl(1)|rsautl(1)>
236L<dgst(1)|dgst(1)>, L<rsa(1)|rsa(1)>, L<genrsa(1)|genrsa(1)>
237