rsa - RSA key processing tool
SYNOPSIS
openssl rsa [-inform PEM|NET|DER] [-outform PEM|NET|DER]
[-in filename] [-passin arg] [-out filename] [-passout
arg] [-sgckey] [-des] [-des3] [-idea] [-text] [-noout]
[-modulus] [-check] [-pubin] [-pubout]
DESCRIPTION
The rsa command processes RSA 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
utility.
COMMAND OPTIONS
-inform DER|NET|PEM
This specifies the input format. The DER option uses
an ASN1 DER encoded form compatible with the PKCS#1
RSAPrivateKey or SubjectPublicKeyInfo format. The PEM
form is the default format: it consists of the DER
format base64 encoded with additional header and
footer lines. On input PKCS#8 format private keys are
also accepted. The NET form is a format is described
in the NOTES section.
-outform DER|NET|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 if this option 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 password
the output file password source. For more information
about the format of arg see the PASS PHRASE ARGUMENTS
section in openssl(1).
use the modified NET algorithm used with some versions
of Microsoft IIS and SGC keys.
-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 rsa 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 various public or private key
components in plain text in addition to the encoded
version.
-noout
this option prevents output of the encoded version of
the key.
-modulus
this option prints out the value of the modulus of the
key.
-check
this option checks the consistency of an RSA private
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 RSA PRIVATE KEY-----
-----END RSA PRIVATE KEY-----
The PEM public key format uses the header and footer
lines:
-----BEGIN PUBLIC KEY-----
-----END PUBLIC KEY-----
servers and Microsoft IIS .key files, this uses unsalted
RC4 for its encryption. It is not very secure and so
should only be used when necessary.
Some newer version of IIS have additional data in the
exported .key files. To use thse with the utility view the
file with a binary editor and look for the string
"private-key", then trace back to the byte sequence 0x30,
0x82 (this is an ASN1 SEQUENCE). Copy all the data from
this point onwards to another file and use that as the
input to the rsa utility with the -inform NET option. If
you get an error after entering the password try the
-sgckey option.
EXAMPLES
To remove the pass phrase on an RSA private key:
openssl rsa -in key.pem -out keyout.pem
To encrypt a private key using triple DES:
openssl rsa -in key.pem -des3 -out keyout.pem
To convert a private key from PEM to DER format:
openssl rsa -in key.pem -outform DER -out keyout.der
To print out the components of a private key to standard
output:
openssl rsa -in key.pem -text -noout
To just output the public part of a private key:
openssl rsa -in key.pem -pubout -out pubkey.pem
BUGS
The command line password arguments don't currently work
with NET format.
There should be an option that automatically handles .key
files, without having to manually edit them.
SEE ALSO
pkcs8(1), dsa(1), genrsa(1), gendsa(1)
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