Backward Compatibility Restriction
Any image prior to Cisco IOS Release 12.3(7)T does not support encrypted keys. To prevent your router from losing all encrypted
keys, ensure that only unencrypted keys are written to NVRAM before booting an image prior to Cisco IOS Release 12.3(7)T.
If you must download an image prior to Cisco IOS Release 12.3(7)T, decrypt the key and immediately save the configuration
so the downloaded image does not overwrite the configuration.
Interaction with Applications
An encrypted key is not effective after the router boots up until you manually unlock the key (via the crypto key unlock rsa command). Depending on which key pairs are encrypted, this functionality may adversely affect applications such as IP security
(IPsec), SSH, and SSL; that is, management of the router over a secure channel may not be possible until the necessary key
pair is unlocked.
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