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