rsa(1ssl)
NAME
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 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
pkcs8(1), dsa(1), genrsa(1), gendsa(1)
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
