<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class="">Now I understand how the handshake works (maybe), I used Wireshark to see the cipher suites and the selected one for HTTPS to our companies website<br class=""><br class="">TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384<br class=""><br class="">As taken from [1] to mean:<br class=""><br class=""><div class="">TLS - the protocol used</div><div class="">ECDHE - the key exchange mechanism</div><div class="">RSA - the algorithm of the authentication key</div><div class="">AES - the symmetric encryption algorithm</div>256 - the key size of the above<div class="">GCM - the mode of the above</div><div class="">SHA384 - the MAC used by the algorithm</div><br class="">AES_256_GCM being the cipher<br class=""><br class="">This seems like a strong encryption for message data, and dare I say, stronger than the default ciphers available to native VPN clients on OSX and Windows 10. Although both seem adequately strong for todays standards.</div><div class=""><br class=""></div><div class="">[1] <a href="https://scotthelme.co.uk/https-cheat-sheet/" class="">https://scotthelme.co.uk/https-cheat-sheet/</a> </div><div class=""><br class=""></div>
<div><br class=""><blockquote type="cite" class=""><div class="">On 19 Jul 2018, at 09:38, Tobias Brunner <<a href="mailto:tobias@strongswan.org" class="">tobias@strongswan.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Hi Christian,<br class=""><br class=""><blockquote type="cite" class="">I am also<br class="">limited to the native OSX/Windows VPN clients which currently support a<br class="">maximum of aes256-sha256-prfsha256-ecp256-modp2048 (Windows does not<br class="">support ecp)<br class=""></blockquote><br class="">It does (at least on Windows 10), you just have to enable it via<br class="">PowerShell (see [1]).<br class=""><br class=""><blockquote type="cite" class="">Apart from IPSEC being Layer 3 and HTTP being Layer 6, meaning that<br class="">should a VPN client be infected with a worm, it is easier for that worm<br class="">to infect the network, I’m struggling to see another security argument.<br class=""></blockquote><br class="">Probably depends on the IPsec policies (e.g. if split tunneling is used<br class="">or even only single protocols/ports are allowed) and the firewall rules<br class="">on the remote end vs. what is available via HTTPS connection (e.g. if<br class="">the latter creates a VPN too or the malware can hijack the VDI somehow).<br class=""><br class=""><blockquote type="cite" class="">Data encrypted over RSA 4096 SHA-2 on paper seems a secure connection.<br class=""></blockquote><br class="">Nobody encrypts large amounts of data via RSA, if anything it's used to<br class="">encrypt a symmetric key that's then used to encrypt the data, but mostly<br class="">only for authentication (digital signatures). The key exchange usually<br class="">happens via ephemeral DH (in IKE always and nowadays in TLS too).<br class=""><br class=""><blockquote type="cite" class=""> Whereas IKE also uses a certificate to do the KeyExchange before<br class="">logging in <br class=""></blockquote><br class="">No, the key exchange is done via DH, the certificate is used for<br class="">authentication only (to prevent MITM attacks).<br class=""><br class=""><blockquote type="cite" class="">and then encrypting the data with ESP, so the ciphers used on<br class="">ESP I feel is the comparison that needs to be made.<br class=""></blockquote><br class="">The cryptographic strength of all ciphers in a cipher suite should be<br class="">consistent. For instance, using AES-256 for ESP is basically wasted<br class="">when using MODP-2048 because that has only an estimated strength of 112<br class="">bits (same for ECP-256 whose estimated strength is 128 bits).<br class=""><br class=""><blockquote type="cite" class="">I will have a read of that Cipher suites page, but if I remember<br class="">correctly, it is not a comparison but a standpoint.<br class=""></blockquote><br class="">It mainly documents the available options (there are some warnings/notes<br class="">though). [2] has some general pointers regarding the security of<br class="">IKE/IPsec connections.<br class=""><br class="">Regards,<br class="">Tobias<br class=""><br class="">[1]<br class=""><a href="https://wiki.strongswan.org/projects/strongswan/wiki/WindowsClients#AES-256-CBC-and-MODP2048" class="">https://wiki.strongswan.org/projects/strongswan/wiki/WindowsClients#AES-256-CBC-and-MODP2048</a><br class="">[2]<br class="">https://wiki.strongswan.org/projects/strongswan/wiki/SecurityRecommendations<br class=""></div></div></blockquote></div><br class=""></body></html>