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]
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.
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.
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:
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)
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