This article discusses how to generate an unencrypted private key and public certificate pair that is suitable for use with HTTPS, FTPS, and the administrative port for Secure FTP Server-FIPS. (To generate an encrypted key/certificate pair, refer to Generating an Encrypted Private Key and Self-Signed Public Certificate.)
General Information
When operating in a FIPS-approved mode, PKI key/certificates must be between 1024- bits and 4096-bits, inclusive.
The supported cipher combinations allowed for SSL negotiation are limited to:
SSLv3/TLSv1 - RSA Key Exchange, RSA Authentication, 256 bit AES encryption, and SHA1 HMAC
SSLv3/TLSv1 - RSA Key Exchange, RSA Authentication, 168 bit 3DES encryption, and SHA1 HMAC
SSLv3/TLSv1 - RSA Key Exchange, RSA Authentication, 128 bit AES encryption, and SHA1 HMAC
Each of the above combinations uses RSA key exchange; therefore, RSA-based key/certificates must be used.
Procedure
These instructions assume you have downloaded and installed the Windows binary distribution of OpenSSL. Refer to Using OpenSSL for the basic instructions.
Generate an RSA private key:
>C:\Openssl\bin\openssl.exe genrsa -out <Key Filename> <Key Size>
Where:
<Key Filename> is the desired filename for the private key file
<Key Size> is the desired key length of either 1024, 2048, or 4096
For example, type:
>C:\Openssl\bin\openssl.exe genrsa -out my_key.key 2048
Generate a Certificate Signing Request:
In version 0.9.8g:
>C:\Openssl\bin\openssl.exe req -new -key <Key Filename> -out <Request Filename> -config C:\Openssl\bin\openssl.cnf
-OR-
In version 0.9.8h and later:
>C:\Openssl\bin\openssl.exe req -new -key <Key Filename> -out <Request Filename> -config C:\Openssl\bin\openssl.cfg
Where:
<Key Filename> is the input filename of the previously generated private key
<Request Filename> is the output filename of the certificate signing request
For example, type:
>C:\Openssl\bin\openssl.exe req -new -key my_key.key -out my_request.csr -config C:\Openssl\bin\openssl.cnf
Follow the on-screen prompts for the required certificate request information.
Generate a self-signed public certificate based on the request
>C:\Openssl\bin\openssl.exe x509 -req -days 3650 -in <Request Filename> -signkey <Key Filename> -out <Certificate Filename>
Where:
<Request Filename> is the input filename of the certificate signing request
<Key Filename> is the input filename of the previously generated private key
<Certificate Filename> is the output filename of the public certificate
For example, type:
>C:\Openssl\bin\openssl.exe x509 -req -days 3650 -in my_request.csr -signkey my_key.key -out my_cert.crt
(Optional) You may now delete the request file as it is no longer needed.
The resulting private key file and public certificate file can now be used within Secure FTP Server - FIPS.