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] [-des] [-des3]
    [-idea] [-text] [-noout] [-modulus] [-check] [-pubin] [-pubout]
    [-engine id]

DESCRIPTION
    The rsa command processes RSA keys. They can be converted between vari-
    ous 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 Subject-
   PublicKeyInfo format. The PEM form is the default format: it con-
   sists 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 sec-
   tion.

    -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 for-
   mat 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 file-
   name 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.

    -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.

    -engine id
   specifying an engine (by it's unique id string) will cause req 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 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 edi-
    tor 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 for-
    mat.

    There should be an option that automatically handles .key files, with-
    out having to manually edit them.

SEE ALSO
   pkcs8(1),dsa(1),genrsa(1),gendsa(1)