NAME

dsa − DSA key processing

SYNOPSIS

openssl dsa [−inform PEM | DER] [−outform PEM | DER] [−in filename] [−passin arg] [−out filename] [−passout arg] [−des] [−des3] [−idea] [−text] [−noout] [−modulus] [−pubin] [−pubout]

OPTIONS

−inform DER|PEM
Specifies the input format. The DER option with a private key uses an ASN1 DER encoded form of an ASN.1 SEQUENCE consisting of the values of version (currently zero), p, q, g, the public and private key components respectively as ASN.1 INTEGERs. When used with a public key it uses a SubjectPublicKeyInfo structure. It is an error if the key is not DSA. 

The PEM form is the default format. It consists of the DER format base64 encoded with additional header and footer lines. In the case of a private key PKCS#8 format is also accepted. 

−outform DER|PEM
Specifies the output format. The options have the same meaning as the −inform option. 

−in filename
Specifies the input filename to read a key from or standard input if this option is not specified. If the key is encrypted, there will be a prompt for a pass phrase.

−passin arg
Input file password source. For more information about the format of arg, see the Pass Phrase Arguments section in openssl(1ssl). 

−outfilename
Specifies the output filename to write a key to or standard output by is not specified. If any encryption options are set there will be a prompt for a pass phrase. The output filename should not be the same as the input filename.

−passout arg
Output file password source. For more information about the format of arg, see the Pass Phrase Arguments section in openssl(1ssl). 

−des|−des3|−idea
These options encrypt the private key with the DES, triple DES, or the  IDEA ciphers respectively before outputting it. There is a prompt for a pass phrase. If none of these options is specified the key is written in plain text. This means that using the dsa utility to read in an encrypted key with no encryption option can be used to remove the pass phrase from a key, or by setting the encryption options it can be use to add or change the pass phrase. These options can only be used with PEM format output files. 

−textPrints the public, private key components and parameters. 

−nooutPrevents output of the encoded version of the key. 

−modulus
Prints the value of the public key component of the key.

−pubinBy default, a private key is read from the input file. With this option a public key is read instead. 

−pubout
By default a private key is output. With this option a public key will be output instead. This option is automatically set if the input is a public key.

DESCRIPTION

The dsa command processes DSA keys. They can be converted between various forms and their components printed out.  This command uses the traditional SSLeay compatible format for private key encryption. Newer applications should use the more secure PKCS#8 format using the pkcs8 command. 

NOTES

The PEM private key format uses the header and footer lines:

 -----BEGIN DSA PRIVATE KEY-----
 -----END DSA PRIVATE KEY-----

The PEM public key format uses the header and footer lines:

 -----BEGIN PUBLIC KEY-----
 -----END PUBLIC KEY-----

EXAMPLES

To remove the pass phrase on a DSA private key:

 openssl dsa -in key.pem -out keyout.pem

To encrypt a private key using triple DES:

 openssl dsa -in key.pem -des3 -out keyout.pem

To convert a private key from PEM to DER format:

 openssl dsa -in key.pem -outform DER -out keyout.der

To print out the components of a private key to standard output:

 openssl dsa -in key.pem -text -noout

To just output the public part of a private key:

 openssl dsa -in key.pem -pubout -out pubkey.pem

SEE ALSO

Commands: dsaparam(1ssl), gendsa(1ssl), rsa(1ssl), genrsa(1ssl)