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)