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rsa - RSA key processing tool
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[B<-inform PEM|NET|DER>]
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[B<-outform PEM|NET|DER>]
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The B<rsa> command processes RSA keys. They can be converted between various
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forms and their components printed out. B<Note> this command uses the
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traditional SSLeay compatible format for private key encryption: newer
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applications should use the more secure PKCS#8 format using the B<pkcs8>
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=head1 COMMAND OPTIONS
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=item B<-inform DER|NET|PEM>
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This specifies the input format. The B<DER> option uses an ASN1 DER encoded
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form compatible with the PKCS#1 RSAPrivateKey or SubjectPublicKeyInfo format.
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The B<PEM> form is the default format: it consists of the B<DER> format base64
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encoded with additional header and footer lines. On input PKCS#8 format private
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keys are also accepted. The B<NET> form is a format is described in the B<NOTES>
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=item B<-outform DER|NET|PEM>
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This specifies the output format, the options have the same meaning as the
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This specifies the input filename to read a key from or standard input if this
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option is not specified. If the key is encrypted a pass phrase will be
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the input file password source. For more information about the format of B<arg>
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see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
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=item B<-out filename>
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This specifies the output filename to write a key to or standard output if this
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option is not specified. If any encryption options are set then a pass phrase
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will be prompted for. The output filename should B<not> be the same as the input
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=item B<-passout password>
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the output file password source. For more information about the format of B<arg>
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see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
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use the modified NET algorithm used with some versions of Microsoft IIS and SGC
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=item B<-des|-des3|-idea>
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These options encrypt the private key with the DES, triple DES, or the
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IDEA ciphers respectively before outputting it. A pass phrase is prompted for.
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If none of these options is specified the key is written in plain text. This
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means that using the B<rsa> utility to read in an encrypted key with no
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encryption option can be used to remove the pass phrase from a key, or by
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setting the encryption options it can be use to add or change the pass phrase.
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These options can only be used with PEM format output files.
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prints out the various public or private key components in
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plain text in addition to the encoded version.
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this option prevents output of the encoded version of the key.
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this option prints out the value of the modulus of the key.
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this option checks the consistency of an RSA private key.
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by default a private key is read from the input file: with this
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option a public key is read instead.
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by default a private key is output: with this option a public
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key will be output instead. This option is automatically set if
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the input is a public key.
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specifying an engine (by it's unique B<id> string) will cause B<req>
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to attempt to obtain a functional reference to the specified engine,
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thus initialising it if needed. The engine will then be set as the default
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for all available algorithms.
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The PEM private key format uses the header and footer lines:
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-----BEGIN RSA PRIVATE KEY-----
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-----END RSA PRIVATE KEY-----
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The PEM public key format uses the header and footer lines:
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-----BEGIN PUBLIC KEY-----
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-----END PUBLIC KEY-----
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The B<NET> form is a format compatible with older Netscape servers
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and Microsoft IIS .key files, this uses unsalted RC4 for its encryption.
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It is not very secure and so should only be used when necessary.
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Some newer version of IIS have additional data in the exported .key
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files. To use these with the utility, view the file with a binary editor
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and look for the string "private-key", then trace back to the byte
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sequence 0x30, 0x82 (this is an ASN1 SEQUENCE). Copy all the data
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from this point onwards to another file and use that as the input
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to the B<rsa> utility with the B<-inform NET> option. If you get
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an error after entering the password try the B<-sgckey> option.
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To remove the pass phrase on an RSA private key:
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openssl rsa -in key.pem -out keyout.pem
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To encrypt a private key using triple DES:
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openssl rsa -in key.pem -des3 -out keyout.pem
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To convert a private key from PEM to DER format:
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openssl rsa -in key.pem -outform DER -out keyout.der
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To print out the components of a private key to standard output:
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openssl rsa -in key.pem -text -noout
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To just output the public part of a private key:
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openssl rsa -in key.pem -pubout -out pubkey.pem
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The command line password arguments don't currently work with
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There should be an option that automatically handles .key files,
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without having to manually edit them.
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L<pkcs8(1)|pkcs8(1)>, L<dsa(1)|dsa(1)>, L<genrsa(1)|genrsa(1)>,
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L<gendsa(1)|gendsa(1)>