rsa

RSA(1SSL)                           OpenSSL                          RSA(1SSL)

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>.

1.1.1f                            2023-10-10                         RSA(1SSL)