TLS PSK

[reesew]

What is the status of PSK support for TLS? I saw a TODO line in node/lib/_tls_wrap.js, is that representative of the current status? If it isn't implemented, is there any workarounds to be able to use PSK with a node js server?

[mscdex]

/cc @nodejs/crypto

[bnoordhuis]

There's no PSK support at this time. I'm not aware of any workarounds except maybe putting a TLS terminator in front of node. What's your use case?

[reesew]

Main/priority use case is a device that connects to servers using PSK, I think because it is less computationally/battery intensive. That is its only TLS method (ECDHE PSK). Second use case I'm just exploring, using PSK for communication between distributed microservices, rather than setting up a CA or something. I'm not really sure of the best way to ensure encrypted communication between services at this point. TLS terminator may work for the first use case, if I can figure out a good alternative solution for the second, but I'm a little outside my area of expertise

[bnoordhuis]

Speaking from prior experience, PSK is a bit of a hassle unless all peers are configured exactly the same. If your network is heterogeneous, brace yourself for late-night debugging sessions. The custom CA approach, optionally with client certificates, is much easier.

[reesew]

Unfortunate...
Any suggestions on a tls terminator solution? I haven't been able to find anything yet, and it sounds like that might be my only alternative

[bnoordhuis]

I thought Apache's mod_ssl did but seems I was mistaken. Some quick googling suggests there isn't much that supports PSK at the moment.

PSK is not that hard to implement so it might be worth doing in node.js. On the other hand, it's kind of obscure and the tls module is already pretty bulky so I'm a little torn here.

[reesew]

well... there is a TODO comment about it. just saying... (=

[shigeki]

PSK use cases of 3GPP and IoT are described in https://www.ietf.org/proceedings/93/slides/slides-93-tls-6.pdf .

But the current openssl-1.0.2 does not support PSF in PSK(DHE-PSK/ECDHE-PSK) so that it cannot protect encrypted data in the past if pre-shared key is compromised.

 ./openssl ciphers -v |grep PSK
PSK-AES256-CBC-SHA      SSLv3 Kx=PSK      Au=PSK  Enc=AES(256)  Mac=SHA1
PSK-AES128-CBC-SHA      SSLv3 Kx=PSK      Au=PSK  Enc=AES(128)  Mac=SHA1
PSK-RC4-SHA             SSLv3 Kx=PSK      Au=PSK  Enc=RC4(128)  Mac=SHA1
PSK-3DES-EDE-CBC-SHA    SSLv3 Kx=PSK      Au=PSK  Enc=3DES(168) Mac=SHA1

Unless we have clear requirements to use PSK, I'd like to wait for DHE-PSK/ECDHE-PSK to be supported.

[evanlucas]

Going ahead and closing due to inactivity. Feel free to reopen if necessary. Thanks!