How to Protect Yourself from NSA Attacks on 1024-bit DH

Re:How to Protect Yourself from NSA Attacks on 1024-bit DH by decisiveness on Friday October 16, 2015 @01:24PM (#10400746)

Easy-rsa[1] (OpenVPN's key/cert generation/signing tool) version 3 will generate a 2048 bit diffie hellman key by default. Previous versions of easy-rsa used 1024 bit as default.

Here is a comment written in the vars configuration file for easy-rsa 2.2.2:

    # Increase this to 2048 if you
    # are paranoid.  This will slow
    # down TLS negotiation performance
    # as well as the one-time DH parms
    # generation process.
    export KEY_SIZE=1024

So if you used easy-rsa version 2.2.2 or previous to generate your diffie hellman key for the server, and didn't increase the default size in the vars file before doing so, your server uses a 1024 bit diffie hellman key.

[1]https://github.com/OpenVPN/easy-rsa

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Re:How to Protect Yourself from NSA Attacks on 1024-bit DH by MrRadar on Friday October 16, 2015 @02:28PM (#10401184)

From what we know as long as it is a custom 1024-bit DH key and you're not being actively targeted by the NSA you are probably okay. That said, you should still upgrade to 2048-bit (or higher, if you're paranoid) ASAP.

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Re:How to Protect Yourself from NSA Attacks on 1024-bit DH by tptacek on Friday October 16, 2015 @04:25PM (#10401785)

No, this is terrible advice. Stop using DH-1024.

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Re:How to Protect Yourself from NSA Attacks on 1024-bit DH by MrRadar on Friday October 16, 2015 @04:37PM (#10401859)

Hence "That said, you should still upgrade to 2048-bit (or higher, if you're paranoid) ASAP."

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Re:How to Protect Yourself from NSA Attacks on 1024-bit DH by diafygi on Sunday October 18, 2015 @10:24AM (#10408296)

How can I tell what DH size I'm using from the OpenVPN client side when I connect to an OpenVPN server?

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