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 PASSPHRASEARGUMENTS 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 PASSPHRASEARGUMENTS section in openssl(1).
-sgckey
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:
The PEM public key format uses the header and footer lines:
-----BEGIN PUBLIC KEY-----
-----END 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 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.
