IronPort - advanced configuration guide

Configuring DomainKeys and DKIM Signing
Signing Keys
5-4
Cisco IronPort AsyncOS 7.6 for Email Advanced Configuration Guide
Chapter 5 Email Authentication
A signing key is the private key stored on the Cisco IronPort appliance. When creating a signing key,
you specify a key size. Larger key sizes are more secure; however, larger keys also can impact
performance. The Cisco IronPort appliance supports keys from 512 bits up to 2048 bits. The 768 - 1024
bit key sizes are considered secure and used by most senders today. Keys based on larger key sizes can
impact performance and are not supported above 2048 bits. For more information about creating signing
keys, see Creating New Signing Keys, page 5-11.
If you are entering an existing key, simply paste it into the form. Another way to use existing signing
keys is to import the key as a text file. For more information about adding existing signing keys, see
Importing or Entering Existing Signing Keys, page 5-12.
Once a key is entered, it is available for use in domain profiles, and will appear in the Signing Key list
in the domain profile:
Figure 5-2 Add Domain Profile Page (DomainKeys)— Signing Keys
Exporting and Importing Signing Keys
You can export your signing keys to a text file on the Cisco IronPort appliance. When you export keys,
all of the keys currently existing on the appliance are put into a text file. For more information about
exporting keys, see Exporting Signing Keys, page 5-11.
You can import keys that have been exported as well.
Note Importing keys causes all of the current keys on the appliance to be replaced.
For more information, see Importing or Entering Existing Signing Keys, page 5-12.
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