Linux "rsa" Command Line Options and Examples

RSA key processing tool

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.

Usage:

openssl rsa [-help] [-inform PEM|NET|DER] [-outform PEM|NET|DER] [-in filename] [-passin arg] [-out filename] [-passout arg] [-aes128] [-aes192] [-aes256] [-camellia128] [-camellia192] [-camellia256] [-des] [-des3] [-idea] [-text] [-noout] [-modulus] [-check] [-pubin] [-pubout] [-RSAPublicKey_in] [-RSAPublicKey_out] [-engine id]

Related Commands

Command Line Options:

-help

Print out a usage message.


                            rsa -help ...

-inform

This specifies the input format. The DER option uses an ASN1 DER encoded form compatible with the PKCS#1RSAPrivateKey or SubjectPublicKeyInfo format. The PEM form is the default format: it consists of the DERformat base64 encoded with additional header and footer lines. On input PKCS#8 format private keys arealso accepted. The NET form is a format is described in the NOTES section.


                            rsa -inform ...

-outform

This specifies the output format, the options have the same meaning as the -inform option.


                            rsa -outform ...

-in

This specifies the input filename to read a key from or standard input if this option is not specified. Ifthe key is encrypted a pass phrase will be prompted for.


                            rsa -in ...

-passin

the input file password source. For more information about the format of arg see the PASS PHRASE ARGUMENTSsection in openssl(1).


                            rsa -passin ...

-out

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 notbe the same as the input filename.


                            rsa -out ...

-passout

the output file password source. For more information about the format of arg see the PASS PHRASEARGUMENTS section in openssl(1).


                            rsa -passout ...

-aes128|-aes192|-aes256|-camellia128|-camellia192|-camellia256|-des|-des3|-idea

These options encrypt the private key with the specified cipher before outputting it. A pass phrase isprompted for. If none of these options is specified the key is written in plain text. This means thatusing the rsa utility to read in an encrypted key with no encryption option can be used to remove the passphrase 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.


                            rsa -aes128|-aes192|-aes256|-camellia128|-camellia192|-camellia256|-des|-des3|-idea ...

-text

prints out the various public or private key components in plain text in addition to the encoded version.


                            rsa -text ...

-noout

this option prevents output of the encoded version of the key.


                            rsa -noout ...

-modulus

this option prints out the value of the modulus of the key.


                            rsa -modulus ...

-check

this option checks the consistency of an RSA private key.


                            rsa -check ...

-pubin

by default a private key is read from the input file: with this option a public key is read instead.


                            rsa -pubin ...

-pubout

by default a private key is output: with this option a public key will be output instead. This option isautomatically set if the input is a public key.


                            rsa -pubout ...

-RSAPublicKey_in

like -pubin and -pubout except RSAPublicKey format is used instead.


                            rsa -RSAPublicKey_in ...

-engine

specifying an engine (by its unique id string) will cause rsa to attempt to obtain a functional referenceto the specified engine, thus initialising it if needed. The engine will then be set as the default forall available algorithms.NOTESThe PEM private key format uses the header and footer lines:


                            rsa -engine ...