1=pod 2 3=head1 NAME 4 5openssl-rsa, 6rsa - RSA key processing tool 7 8=head1 SYNOPSIS 9 10B<openssl> B<rsa> 11[B<-help>] 12[B<-inform PEM|DER>] 13[B<-outform PEM|DER>] 14[B<-in filename>] 15[B<-passin arg>] 16[B<-out filename>] 17[B<-passout arg>] 18[B<-aes128>] 19[B<-aes192>] 20[B<-aes256>] 21[B<-aria128>] 22[B<-aria192>] 23[B<-aria256>] 24[B<-camellia128>] 25[B<-camellia192>] 26[B<-camellia256>] 27[B<-des>] 28[B<-des3>] 29[B<-idea>] 30[B<-text>] 31[B<-noout>] 32[B<-modulus>] 33[B<-check>] 34[B<-pubin>] 35[B<-pubout>] 36[B<-RSAPublicKey_in>] 37[B<-RSAPublicKey_out>] 38[B<-engine id>] 39 40=head1 DESCRIPTION 41 42The B<rsa> command processes RSA keys. They can be converted between various 43forms and their components printed out. B<Note> this command uses the 44traditional SSLeay compatible format for private key encryption: newer 45applications should use the more secure PKCS#8 format using the B<pkcs8> 46utility. 47 48=head1 OPTIONS 49 50=over 4 51 52=item B<-help> 53 54Print out a usage message. 55 56=item B<-inform DER|PEM> 57 58This specifies the input format. The B<DER> option uses an ASN1 DER encoded 59form compatible with the PKCS#1 RSAPrivateKey or SubjectPublicKeyInfo format. 60The B<PEM> form is the default format: it consists of the B<DER> format base64 61encoded with additional header and footer lines. On input PKCS#8 format private 62keys are also accepted. 63 64=item B<-outform DER|PEM> 65 66This specifies the output format, the options have the same meaning and default 67as the B<-inform> option. 68 69=item B<-in filename> 70 71This specifies the input filename to read a key from or standard input if this 72option is not specified. If the key is encrypted a pass phrase will be 73prompted for. 74 75=item B<-passin arg> 76 77The input file password source. For more information about the format of B<arg> 78see L<openssl(1)/Pass Phrase Options>. 79 80=item B<-out filename> 81 82This specifies the output filename to write a key to or standard output if this 83option is not specified. If any encryption options are set then a pass phrase 84will be prompted for. The output filename should B<not> be the same as the input 85filename. 86 87=item B<-passout password> 88 89The output file password source. For more information about the format of B<arg> 90see L<openssl(1)/Pass Phrase Options>. 91 92=item B<-aes128>, B<-aes192>, B<-aes256>, B<-aria128>, B<-aria192>, B<-aria256>, B<-camellia128>, B<-camellia192>, B<-camellia256>, B<-des>, B<-des3>, B<-idea> 93 94These options encrypt the private key with the specified 95cipher before outputting it. A pass phrase is prompted for. 96If none of these options is specified the key is written in plain text. This 97means that using the B<rsa> utility to read in an encrypted key with no 98encryption option can be used to remove the pass phrase from a key, or by 99setting the encryption options it can be use to add or change the pass phrase. 100These options can only be used with PEM format output files. 101 102=item B<-text> 103 104Prints out the various public or private key components in 105plain text in addition to the encoded version. 106 107=item B<-noout> 108 109This option prevents output of the encoded version of the key. 110 111=item B<-modulus> 112 113This option prints out the value of the modulus of the key. 114 115=item B<-check> 116 117This option checks the consistency of an RSA private key. 118 119=item B<-pubin> 120 121By default a private key is read from the input file: with this 122option a public key is read instead. 123 124=item B<-pubout> 125 126By default a private key is output: with this option a public 127key will be output instead. This option is automatically set if 128the input is a public key. 129 130=item B<-RSAPublicKey_in>, B<-RSAPublicKey_out> 131 132Like B<-pubin> and B<-pubout> except B<RSAPublicKey> format is used instead. 133 134=item B<-engine id> 135 136Specifying an engine (by its unique B<id> string) will cause B<rsa> 137to attempt to obtain a functional reference to the specified engine, 138thus initialising it if needed. The engine will then be set as the default 139for all available algorithms. 140 141=back 142 143=head1 NOTES 144 145The PEM private key format uses the header and footer lines: 146 147 -----BEGIN RSA PRIVATE KEY----- 148 -----END RSA PRIVATE KEY----- 149 150The PEM public key format uses the header and footer lines: 151 152 -----BEGIN PUBLIC KEY----- 153 -----END PUBLIC KEY----- 154 155The PEM B<RSAPublicKey> format uses the header and footer lines: 156 157 -----BEGIN RSA PUBLIC KEY----- 158 -----END RSA PUBLIC KEY----- 159 160=head1 EXAMPLES 161 162To remove the pass phrase on an RSA private key: 163 164 openssl rsa -in key.pem -out keyout.pem 165 166To encrypt a private key using triple DES: 167 168 openssl rsa -in key.pem -des3 -out keyout.pem 169 170To convert a private key from PEM to DER format: 171 172 openssl rsa -in key.pem -outform DER -out keyout.der 173 174To print out the components of a private key to standard output: 175 176 openssl rsa -in key.pem -text -noout 177 178To just output the public part of a private key: 179 180 openssl rsa -in key.pem -pubout -out pubkey.pem 181 182Output the public part of a private key in B<RSAPublicKey> format: 183 184 openssl rsa -in key.pem -RSAPublicKey_out -out pubkey.pem 185 186=head1 BUGS 187 188There should be an option that automatically handles .key files, 189without having to manually edit them. 190 191=head1 SEE ALSO 192 193L<pkcs8(1)>, L<dsa(1)>, L<genrsa(1)>, 194L<gendsa(1)> 195 196=head1 COPYRIGHT 197 198Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved. 199 200Licensed under the OpenSSL license (the "License"). You may not use 201this file except in compliance with the License. You can obtain a copy 202in the file LICENSE in the source distribution or at 203L<https://www.openssl.org/source/license.html>. 204 205=cut 206