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] [-engine id]
DESCRIPTION
The dsa command processes DSA keys. They can be converted
between various forms and their components printed out.
Note: 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 OPTIONS
-inform DER|PEM
This 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
This specifies the output format, the options have the same
meaning as the -inform option.
-in filename
This specifies the input filename to read a key from or standard
input if this option is not specified. If the key is encrypted a
pass phrase will be prompted for.
-passin arg
the input file password source. For more information about
the format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
-out filename
This specifies the output filename to write a key to or standard
output by is not specified. If any encryption options are set then
a pass phrase will be prompted for. The output filename should not
be the same as the input filename.
-passout arg
the output file password source. For more information about
the format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
-des|-des3|-idea
These options encrypt the private key with the DES, triple
DES, or the IDEA ciphers respectively before outputting it. A pass
phrase is prompted for. 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.
-text
prints out the public, private key components and parameters.
-noout
this option prevents output of the encoded version of the
key.
-modulus
this option prints out the value of the public key component
of the key.
-pubin
by 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.
-engine id
specifying an engine (by it's unique id string) will cause
req to attempt to obtain a functional reference to the specified
engine, thus initialising it if needed. The engine will then be
set as the default for all available algorithms.
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
dsaparam(1), gendsa(1), rsa(1), genrsa(1)
