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.
OPTIONS
-help
Print out a usage message.
-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 -out filename
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.
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:
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