1=pod 2 3=head1 NAME 4 5dsa - DSA key processing 6 7=head1 SYNOPSIS 8 9B<openssl> B<dsa> 10[B<-inform PEM|DER>] 11[B<-outform PEM|DER>] 12[B<-in filename>] 13[B<-passin arg>] 14[B<-out filename>] 15[B<-passout arg>] 16[B<-des>] 17[B<-des3>] 18[B<-idea>] 19[B<-text>] 20[B<-noout>] 21[B<-modulus>] 22[B<-pubin>] 23[B<-pubout>] 24[B<-engine id>] 25 26=head1 DESCRIPTION 27 28The B<dsa> command processes DSA keys. They can be converted between various 29forms and their components printed out. B<Note> This command uses the 30traditional SSLeay compatible format for private key encryption: newer 31applications should use the more secure PKCS#8 format using the B<pkcs8> 32 33=head1 COMMAND OPTIONS 34 35=over 4 36 37=item B<-inform DER|PEM> 38 39This specifies the input format. The B<DER> option with a private key uses 40an ASN1 DER encoded form of an ASN.1 SEQUENCE consisting of the values of 41version (currently zero), p, q, g, the public and private key components 42respectively as ASN.1 INTEGERs. When used with a public key it uses a 43SubjectPublicKeyInfo structure: it is an error if the key is not DSA. 44 45The B<PEM> form is the default format: it consists of the B<DER> format base64 46encoded with additional header and footer lines. In the case of a private key 47PKCS#8 format is also accepted. 48 49=item B<-outform DER|PEM> 50 51This specifies the output format, the options have the same meaning as the 52B<-inform> option. 53 54=item B<-in filename> 55 56This specifies the input filename to read a key from or standard input if this 57option is not specified. If the key is encrypted a pass phrase will be 58prompted for. 59 60=item B<-passin arg> 61 62the input file 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=item B<-out filename> 66 67This specifies the output filename to write a key to or standard output by 68is not specified. If any encryption options are set then a pass phrase will be 69prompted for. The output filename should B<not> be the same as the input 70filename. 71 72=item B<-passout arg> 73 74the output file password source. For more information about the format of B<arg> 75see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 76 77=item B<-des|-des3|-idea> 78 79These options encrypt the private key with the DES, triple DES, or the 80IDEA ciphers respectively before outputting it. A pass phrase is prompted for. 81If none of these options is specified the key is written in plain text. This 82means that using the B<dsa> utility to read in an encrypted key with no 83encryption option can be used to remove the pass phrase from a key, or by 84setting the encryption options it can be use to add or change the pass phrase. 85These options can only be used with PEM format output files. 86 87=item B<-text> 88 89prints out the public, private key components and parameters. 90 91=item B<-noout> 92 93this option prevents output of the encoded version of the key. 94 95=item B<-modulus> 96 97this option prints out the value of the public key component of the key. 98 99=item B<-pubin> 100 101by default a private key is read from the input file: with this option a 102public key is read instead. 103 104=item B<-pubout> 105 106by default a private key is output. With this option a public 107key will be output instead. This option is automatically set if the input is 108a public key. 109 110=item B<-engine id> 111 112specifying an engine (by it's unique B<id> string) will cause B<req> 113to attempt to obtain a functional reference to the specified engine, 114thus initialising it if needed. The engine will then be set as the default 115for all available algorithms. 116 117=back 118 119=head1 NOTES 120 121The PEM private key format uses the header and footer lines: 122 123 -----BEGIN DSA PRIVATE KEY----- 124 -----END DSA PRIVATE KEY----- 125 126The PEM public key format uses the header and footer lines: 127 128 -----BEGIN PUBLIC KEY----- 129 -----END PUBLIC KEY----- 130 131=head1 EXAMPLES 132 133To remove the pass phrase on a DSA private key: 134 135 openssl dsa -in key.pem -out keyout.pem 136 137To encrypt a private key using triple DES: 138 139 openssl dsa -in key.pem -des3 -out keyout.pem 140 141To convert a private key from PEM to DER format: 142 143 openssl dsa -in key.pem -outform DER -out keyout.der 144 145To print out the components of a private key to standard output: 146 147 openssl dsa -in key.pem -text -noout 148 149To just output the public part of a private key: 150 151 openssl dsa -in key.pem -pubout -out pubkey.pem 152 153=head1 SEE ALSO 154 155L<dsaparam(1)|dsaparam(1)>, L<gendsa(1)|gendsa(1)>, L<rsa(1)|rsa(1)>, 156L<genrsa(1)|genrsa(1)> 157 158=cut 159