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<-aes128>] 17[B<-aes192>] 18[B<-aes256>] 19[B<-camellia128>] 20[B<-camellia192>] 21[B<-camellia256>] 22[B<-des>] 23[B<-des3>] 24[B<-idea>] 25[B<-text>] 26[B<-noout>] 27[B<-modulus>] 28[B<-pubin>] 29[B<-pubout>] 30[B<-engine id>] 31 32=head1 DESCRIPTION 33 34The B<dsa> command processes DSA keys. They can be converted between various 35forms and their components printed out. B<Note> This command uses the 36traditional SSLeay compatible format for private key encryption: newer 37applications should use the more secure PKCS#8 format using the B<pkcs8> 38 39=head1 COMMAND OPTIONS 40 41=over 4 42 43=item B<-inform DER|PEM> 44 45This specifies the input format. The B<DER> option with a private key uses 46an ASN1 DER encoded form of an ASN.1 SEQUENCE consisting of the values of 47version (currently zero), p, q, g, the public and private key components 48respectively as ASN.1 INTEGERs. When used with a public key it uses a 49SubjectPublicKeyInfo structure: it is an error if the key is not DSA. 50 51The B<PEM> form is the default format: it consists of the B<DER> format base64 52encoded with additional header and footer lines. In the case of a private key 53PKCS#8 format is also accepted. 54 55=item B<-outform DER|PEM> 56 57This specifies the output format, the options have the same meaning as the 58B<-inform> option. 59 60=item B<-in filename> 61 62This specifies the input filename to read a key from or standard input if this 63option is not specified. If the key is encrypted a pass phrase will be 64prompted for. 65 66=item B<-passin arg> 67 68the input file password source. For more information about the format of B<arg> 69see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 70 71=item B<-out filename> 72 73This specifies the output filename to write a key to or standard output by 74is not specified. If any encryption options are set then a pass phrase will be 75prompted for. The output filename should B<not> be the same as the input 76filename. 77 78=item B<-passout arg> 79 80the output file password source. For more information about the format of B<arg> 81see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 82 83=item B<-aes128|-aes192|-aes256|-camellia128|-camellia192|-camellia256|-des|-des3|-idea> 84 85These options encrypt the private key with the specified 86cipher 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<dsa> 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 public, private key components and parameters. 96 97=item B<-noout> 98 99this option prevents output of the encoded version of the key. 100 101=item B<-modulus> 102 103this option prints out the value of the public key component of the key. 104 105=item B<-pubin> 106 107by default a private key is read from the input file: with this option a 108public key is read instead. 109 110=item B<-pubout> 111 112by default a private key is output. With this option a public 113key will be output instead. This option is automatically set if the input is 114a public key. 115 116=item B<-engine id> 117 118specifying an engine (by its unique B<id> string) will cause B<dsa> 119to attempt to obtain a functional reference to the specified engine, 120thus initialising it if needed. The engine will then be set as the default 121for all available algorithms. 122 123=back 124 125=head1 NOTES 126 127The PEM private key format uses the header and footer lines: 128 129 -----BEGIN DSA PRIVATE KEY----- 130 -----END DSA PRIVATE KEY----- 131 132The PEM public key format uses the header and footer lines: 133 134 -----BEGIN PUBLIC KEY----- 135 -----END PUBLIC KEY----- 136 137=head1 EXAMPLES 138 139To remove the pass phrase on a DSA private key: 140 141 openssl dsa -in key.pem -out keyout.pem 142 143To encrypt a private key using triple DES: 144 145 openssl dsa -in key.pem -des3 -out keyout.pem 146 147To convert a private key from PEM to DER format: 148 149 openssl dsa -in key.pem -outform DER -out keyout.der 150 151To print out the components of a private key to standard output: 152 153 openssl dsa -in key.pem -text -noout 154 155To just output the public part of a private key: 156 157 openssl dsa -in key.pem -pubout -out pubkey.pem 158 159=head1 SEE ALSO 160 161L<dsaparam(1)|dsaparam(1)>, L<gendsa(1)|gendsa(1)>, L<rsa(1)|rsa(1)>, 162L<genrsa(1)|genrsa(1)> 163 164=cut 165