crypto key bit length ?

[tedauction]

Hello, when generating crypto keys on newly purchased switches and routers, are most people these days using 2048 length or still 1024 ?

Thanks kindly.

[Milos Megis · Accepted solution]

Hi,
technically for SSH v2 you need at least 768 bits.

1024 bits should be secure, but if you want to use this key as long term (tens of years) without need to change it, then choose as much as it is supported on device.
I think that it is 4096 bit what takes about 5 minutes to generate key.

But network devices are usually replaced after 10 - 15 years so 2048 bits length key should be secure during whole time, and it will be generated in few seconds.
(When you will replace device, you will have to change also key)

Everything above is just my opinion, so if I am wrong please correct me someone.
(And regarding question I prefer 2048 bit key)

[Karsten Iwen · Accepted solution]

Many publications recommend a minimum of 2048 bit. (one good ressource is https://www.keylength.com). I would say if someone is using a keylength below this nowadays, he/she doesn't care about security.