/usr/man/cat.1/openssl-rsa.1
RSA(1) OpenSSL RSA(1)
NAME
openssl-rsa, 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] [-aes128] [-aes192] [-aes256] [-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.
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
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RSA(1) OpenSSL RSA(1)
about the format of arg see the PASS PHRASE ARGUMENTS
section in openssl(1).
-sgckey
use the modified NET algorithm used with some versions
of Microsoft IIS and SGC keys.
-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 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
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RSA(1) OpenSSL RSA(1)
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-----
The NET form is a format compatible with older Netscape
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 these 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
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RSA(1) OpenSSL RSA(1)
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
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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See also rsa(1)
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