1
2=pod
3
4=head1 NAME
5
6rsa - RSA key processing tool
7
8=head1 SYNOPSIS
9
10B<openssl> B<rsa>
11[B<-inform PEM|NET|DER>]
12[B<-outform PEM|NET|DER>]
13[B<-in filename>]
14[B<-passin arg>]
15[B<-out filename>]
16[B<-passout arg>]
17[B<-sgckey>]
18[B<-des>]
19[B<-des3>]
20[B<-idea>]
21[B<-text>]
22[B<-noout>]
23[B<-modulus>]
24[B<-check>]
25[B<-pubin>]
26[B<-pubout>]
27[B<-engine id>]
28
29=head1 DESCRIPTION
30
31The B<rsa> command processes RSA keys. They can be converted between various
32forms and their components printed out. B<Note> this command uses the
33traditional SSLeay compatible format for private key encryption: newer
34applications should use the more secure PKCS#8 format using the B<pkcs8>
35utility.
36
37=head1 COMMAND OPTIONS
38
39=over 4
40
41=item B<-inform DER|NET|PEM>
42
43This specifies the input format. The B<DER> option uses an ASN1 DER encoded
44form compatible with the PKCS#1 RSAPrivateKey or SubjectPublicKeyInfo format.
45The B<PEM> form is the default format: it consists of the B<DER> format base64
46encoded with additional header and footer lines. On input PKCS#8 format private
47keys are also accepted. The B<NET> form is a format is described in the B<NOTES>
48section.
49
50=item B<-outform DER|NET|PEM>
51
52This specifies the output format, the options have the same meaning as the 
53B<-inform> option.
54
55=item B<-in filename>
56
57This specifies the input filename to read a key from or standard input if this
58option is not specified. If the key is encrypted a pass phrase will be
59prompted for.
60
61=item B<-passin arg>
62
63the input file password source. For more information about the format of B<arg>
64see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
65
66=item B<-out filename>
67
68This specifies the output filename to write a key to or standard output if this
69option is not specified. If any encryption options are set then a pass phrase
70will be prompted for. The output filename should B<not> be the same as the input
71filename.
72
73=item B<-passout password>
74
75the output file password source. For more information about the format of B<arg>
76see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
77
78=item B<-sgckey>
79
80use the modified NET algorithm used with some versions of Microsoft IIS and SGC
81keys.
82
83=item B<-des|-des3|-idea>
84
85These options encrypt the private key with the DES, triple DES, or the 
86IDEA ciphers respectively before outputting it. A pass phrase is prompted for.
87If none of these options is specified the key is written in plain text. This
88means that using the B<rsa> utility to read in an encrypted key with no
89encryption option can be used to remove the pass phrase from a key, or by
90setting the encryption options it can be use to add or change the pass phrase.
91These options can only be used with PEM format output files.
92
93=item B<-text>
94
95prints out the various public or private key components in
96plain text in addition to the encoded version. 
97
98=item B<-noout>
99
100this option prevents output of the encoded version of the key.
101
102=item B<-modulus>
103
104this option prints out the value of the modulus of the key.
105
106=item B<-check>
107
108this option checks the consistency of an RSA private key.
109
110=item B<-pubin>
111
112by default a private key is read from the input file: with this
113option a public key is read instead.
114
115=item B<-pubout>
116
117by default a private key is output: with this option a public
118key will be output instead. This option is automatically set if
119the input is a public key.
120
121=item B<-engine id>
122
123specifying an engine (by it's unique B<id> string) will cause B<req>
124to attempt to obtain a functional reference to the specified engine,
125thus initialising it if needed. The engine will then be set as the default
126for all available algorithms.
127
128=back
129
130=head1 NOTES
131
132The PEM private key format uses the header and footer lines:
133
134 -----BEGIN RSA PRIVATE KEY-----
135 -----END RSA PRIVATE KEY-----
136
137The PEM public key format uses the header and footer lines:
138
139 -----BEGIN PUBLIC KEY-----
140 -----END PUBLIC KEY-----
141
142The B<NET> form is a format compatible with older Netscape servers
143and Microsoft IIS .key files, this uses unsalted RC4 for its encryption.
144It is not very secure and so should only be used when necessary.
145
146Some newer version of IIS have additional data in the exported .key
147files. To use these with the utility, view the file with a binary editor
148and look for the string "private-key", then trace back to the byte
149sequence 0x30, 0x82 (this is an ASN1 SEQUENCE). Copy all the data
150from this point onwards to another file and use that as the input
151to the B<rsa> utility with the B<-inform NET> option. If you get
152an error after entering the password try the B<-sgckey> option.
153
154=head1 EXAMPLES
155
156To remove the pass phrase on an RSA private key:
157
158 openssl rsa -in key.pem -out keyout.pem
159
160To encrypt a private key using triple DES:
161
162 openssl rsa -in key.pem -des3 -out keyout.pem
163
164To convert a private key from PEM to DER format: 
165
166 openssl rsa -in key.pem -outform DER -out keyout.der
167
168To print out the components of a private key to standard output:
169
170 openssl rsa -in key.pem -text -noout
171
172To just output the public part of a private key:
173
174 openssl rsa -in key.pem -pubout -out pubkey.pem
175
176=head1 BUGS
177
178The command line password arguments don't currently work with
179B<NET> format.
180
181There should be an option that automatically handles .key files,
182without having to manually edit them.
183
184=head1 SEE ALSO
185
186L<pkcs8(1)|pkcs8(1)>, L<dsa(1)|dsa(1)>, L<genrsa(1)|genrsa(1)>,
187L<gendsa(1)|gendsa(1)> 
188
189=cut
190