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] [-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.

       -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.

       -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)