RSA
Section: OpenSSL (1)
Updated: 2020-07-28
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NAME
openssl-rsa, rsa - RSA key processing tool
SYNOPSIS
openssl rsa
[
-help]
[
-inform PEM|DER]
[
-outform PEM|DER]
[
-in filename]
[
-passin arg]
[
-out filename]
[
-passout arg]
[
-aes128]
[
-aes192]
[
-aes256]
[
-aria128]
[
-aria192]
[
-aria256]
[
-camellia128]
[
-camellia192]
[
-camellia256]
[
-des]
[
-des3]
[
-idea]
[
-text]
[
-noout]
[
-modulus]
[
-check]
[
-pubin]
[
-pubout]
[
-RSAPublicKey_in]
[
-RSAPublicKey_out]
[
-engine id]
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.
OPTIONS
- -help
-
Print out a usage message.
- -inform DER|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.
- -outform DER|PEM
-
This specifies the output format, the options have the same meaning and default
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).
- -aes128, -aes192, -aes256, -aria128, -aria192, -aria256, -camellia128, -camellia192, -camellia256, -des, -des3, -idea
-
These options encrypt the private key with the specified
cipher 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.
- -RSAPublicKey_in, -RSAPublicKey_out
-
Like -pubin and -pubout except RSAPublicKey format is used instead.
- -engine id
-
Specifying an engine (by its unique id string) will cause rsa
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 RSA PRIVATE KEY-----
-----END RSA PRIVATE KEY-----
The PEM public key format uses the header and footer lines:
-----BEGIN PUBLIC KEY-----
-----END PUBLIC KEY-----
The PEM RSAPublicKey format uses the header and footer lines:
-----BEGIN RSA PUBLIC KEY-----
-----END RSA PUBLIC KEY-----
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
Output the public part of a private key in RSAPublicKey format:
openssl rsa -in key.pem -RSAPublicKey_out -out pubkey.pem
BUGS
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)
COPYRIGHT
Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the ``License''). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.