NAME
rsa - RSA key processing tool
LIBRARY
libcrypto, -lcrypto
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 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 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
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
openssl_pkcs8(1),
openssl_dsa(1),
openssl_genrsa(1),
openssl_gendsa(1)