o365 Rotate-DkimSigningConfig to get a DKIM 2048Key

[k-strider]

Hi

 

the information is a bit scatchy on the net but basically inorder to get my DKIM keysize in a o365 domain up to 2048 from 1024 do i need to rotate it twice? i did it once 2 and 1/2 weeks ago acording to NCSC mail check one of my selectors is fine ie 2048 but the other one isnt yet its still 1024... do i just rotate again and if so do i specifiy the keysize as 2048 again?

 

this is what i used to do it.. as not all the commands were in one place and since i mostly deal with google it took a bit of finding.

 

Install-Module -Name ExchangeOnlineManagement -RequiredVersion 2.0.5
Import-Module -Name ExchangeOnlineManagment
Set-ExecutionPolicy unrestricted
Import-Module ExchangeOnlineManagement
Connect-ExchangeOnline -UserPrincipalName [email protected]
Get-DkimSigningConfig -Identity schooldomain.org
Rotate-DkimSigningConfig -KeySize 2048 -Identity schooldomain.org

Edited June 29, 2022 by k-strider

[andy_b]

I rotated twice to get both to 2048.

 

https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/use-dkim-to-validate-outbound-email?view=o365-worldwide#steps-to-manually-upgrade-your-1024-bit-keys-to-2048-bit-dkim-encryption-keys

 

[DrCheese]

Aye done this recently here, you do the first one then wait at least 4 days, then do the other