EASY-RSA Version 2.0-rc1 This is a small RSA key management package, based on the openssl command line tool, that can be found in the easy-rsa subdirectory of the OpenVPN distribution. While this tool is primary concerned with key management for the SSL VPN application space, it can also be used for building web certificates. These are reference notes. For step-by-step instructions, see the HOWTO: http://openvpn.net/howto.html This package is based on the ./pkitool script. Run ./pkitool without arguments for a detailed help message (which is also pasted below). Release Notes for easy-rsa-2.0 * Most functionality has been consolidated into the pkitool script. For compatibility, all previous scripts from 1.0 such as build-key and build-key-server are provided as stubs which call pkitool to do the real work. * pkitool has a --batch flag (enabled by default) which generates keys/certs without needing any interactive input. pkitool can still generate certs/keys using interactive prompting by using the --interact flag. * The inherit-inter script has been provided for creating a new PKI rooted on an intermediate certificate built within a higher-level PKI. See comments in the inherit-inter script for more info. * The openssl.cnf file has been modified. pkitool will not work with the openssl.cnf file included with previous easy-rsa releases. * The vars file has been modified -- the following extra variables have been added: EASY_RSA, CA_EXPIRE, KEY_EXPIRE. * The make-crl and revoke-crt scripts have been removed and are replaced by the revoke-full script. * The "Organizational Unit" X509 field can be set using the KEY_OU environmental variable before calling pkitool. * This release only affects the Linux/Unix version of easy-rsa. The Windows version (written to use the Windows shell) is unchanged. * Use the revoke-full script to revoke a certificate, and generate (or update) the crl.pem file in the keys directory (as set by the vars script). Then use "crl-verify crl.pem" in your OpenVPN server config file, so that OpenVPN can reject any connections coming from clients which present a revoked certificate. Usage for the script is: revoke-full Note this this procedure is primarily designed to revoke client certificates. You could theoretically use this method to revoke server certificates as well, but then you would need to propagate the crl.pem file to all clients as well, and have them include "crl-verify crl.pem" in their configuration files. * PKCS#11 support was added. * For those interested in using this tool to generate web certificates, A variant of the easy-rsa package that allows the creation of multi-domain certificates with subjectAltName can be obtained from here: http://www.bisente.com/proyectos/easy-rsa-subjectaltname/ INSTALL easy-rsa 1. Edit vars. 2. Set KEY_CONFIG to point to the correct openssl-.cnf file included in this distribution. 3. Set KEY_DIR to point to a directory which will contain all keys, certificates, etc. This directory need not exist, and if it does, it will be deleted with rm -rf, so BE CAREFUL how you set KEY_DIR. 4. (Optional) Edit other fields in vars per your site data. You may want to increase KEY_SIZE to 2048 if you are paranoid and don't mind slower key processing, but certainly 1024 is fine for testing purposes. KEY_SIZE must be compatible across both peers participating in a secure SSL/TLS connection. 5. (Optional) If you intend to use PKCS#11, install openssl >= 0.9.7, install the following components from www.opensc.org: - opensc >= 0.10.0 - engine_pkcs11 >= 0.1.3 Update the openssl.cnf to load the engine: - Uncomment pkcs11 under engine_section. - Validate path at dynamic_path under pkcs11_section. 6. . vars 7. ./clean-all 8. As you create certificates, keys, and certificate signing requests, understand that only .key files should be kept confidential. .crt and .csr files can be sent over insecure channels such as plaintext email. IMPORTANT To avoid a possible Man-in-the-Middle attack where an authorized client tries to connect to another client by impersonating the server, make sure to enforce some kind of server certificate verification by clients. There are currently four different ways of accomplishing this, listed in the order of preference: (1) Build your server certificates with specific key usage and extended key usage. The RFC3280 determine that the following attributes should be provided for TLS connections: Mode Key usage Extended key usage --------------------------------------------------------------------------- Client digitalSignature TLS Web Client Authentication keyAgreement digitalSignature, keyAgreement Server digitalSignature, keyEncipherment TLS Web Server Authentication digitalSignature, keyAgreement Now add the following line to your client configuration: remote-cert-tls server This will block clients from connecting to any server which lacks the required extension designation in its certificate, even if the certificate has been signed by the CA which is cited in the OpenVPN configuration file (--ca directive). (3) Use the --tls-remote directive on the client to accept/reject the server connection based on the common name of the server certificate. (3) Use a --tls-verify script or plugin to accept/reject the server connection based on a custom test of the server certificate's embedded X509 subject details. (4) Sign server certificates with one CA and client certificates with a different CA. The client config "ca" directive should reference the server-signing CA while the server config "ca" directive should reference the client-signing CA. NOTES Show certificate fields: openssl x509 -in cert.crt -text PKITOOL documentation pkitool 2.0 Usage: pkitool [options...] [common-name] Options: --batch : batch mode (default) --keysize : Set keysize size : size (default=1024) --interact : interactive mode --server : build server cert --initca : build root CA --inter : build intermediate CA --pass : encrypt private key with password --csr : only generate a CSR, do not sign --sign : sign an existing CSR --pkcs12 : generate a combined PKCS#12 file --pkcs11 : generate certificate on PKCS#11 token lib : PKCS#11 library slot : PKCS#11 slot id : PKCS#11 object id (hex string) label : PKCS#11 object label Standalone options: --pkcs11-slots : list PKCS#11 slots lib : PKCS#11 library --pkcs11-objects : list PKCS#11 token objects lib : PKCS#11 library slot : PKCS#11 slot --pkcs11-init : initialize PKCS#11 token DANGEROUS!!! lib : PKCS#11 library slot : PKCS#11 slot label : PKCS#11 token label Notes: Please edit the vars script to reflect your configuration, then source it with "source ./vars". Next, to start with a fresh PKI configuration and to delete any previous certificates and keys, run "./clean-all". Finally, you can run this tool (pkitool) to build certificates/keys. In order to use PKCS#11 interface you must have opensc-0.10.0 or higher. Generated files and corresponding OpenVPN directives: (Files will be placed in the $KEY_DIR directory, defined in ./vars) ca.crt -> root certificate (--ca) ca.key -> root key, keep secure (not directly used by OpenVPN) .crt files -> client/server certificates (--cert) .key files -> private keys, keep secure (--key) .csr files -> certificate signing request (not directly used by OpenVPN) dh1024.pem or dh2048.pem -> Diffie Hellman parameters (--dh) Examples: pkitool --initca -> Build root certificate pkitool --initca --pass -> Build root certificate with password-protected key pkitool --server server1 -> Build "server1" certificate/key pkitool client1 -> Build "client1" certificate/key pkitool --pass client2 -> Build password-protected "client2" certificate/key pkitool --pkcs12 client3 -> Build "client3" certificate/key in PKCS#12 format pkitool --csr client4 -> Build "client4" CSR to be signed by another CA pkitool --sign client4 -> Sign "client4" CSR pkitool --inter interca -> Build an intermediate key-signing certificate/key Also see ./inherit-inter script. pkitool --pkcs11 /usr/lib/pkcs11/lib1 0 010203 "client5 id" client5 -> Build "client5" certificate/key in PKCS#11 token Typical usage for initial PKI setup. Build myserver, client1, and client2 cert/keys. Protect client2 key with a password. Build DH parms. Generated files in ./keys : [edit vars with your site-specific info] source ./vars ./clean-all ./build-dh -> takes a long time, consider backgrounding ./pkitool --initca ./pkitool --server myserver ./pkitool client1 ./pkitool --pass client2 Typical usage for adding client cert to existing PKI: source ./vars ./pkitool client-new