that's interesting. so it seems to be a hash indeed.
The problem is that we do not know the algorithm, Maybe that's a Cisco secret, I guess.
You could try to kindly ask some cisco support/technicians to provide more information about the security of the credentials and which algorithm is used etc.
I guess the other possibility would be to download the firmware from https://software.cisco.com/download/home/286307836 (this page unfortunately requires a login, I don't have the firmware, nor a cisco login, maybe somebody else have and can download/investigate the firmware and if anything is different between these versions etc ... maybe both 1.6 and 1.8.1 would be interesting)...
the last option would be to guess the algorithm, but it could be kind of everything e.g. salted non-iterated hashes or PBKDF2 or even more modern hashing algorithms... several parameters like the iteration count could be unknown and therefore it could be a very difficult guessing gaming (because of this "secret algorithm", obfuscation).
In my opinion the algorithm should be clearly mentioned in the manual/documentation... this is really a bad obfuscation/hiding game of secret (again, I assume that it's really not common knowledge and public what the password hashing algorithm is, I may be wrong... but it doesn't seem that there is much information available online how these 128 bytes are generated)...
I think the first step should be to reach out to some cisco staff and tell them that for compliance/security reasons you need to know how secure this algorithm is and how you can double-check the security by being able to reproduce these password hashing steps.
The problem is that we do not know the algorithm, Maybe that's a Cisco secret, I guess.
You could try to kindly ask some cisco support/technicians to provide more information about the security of the credentials and which algorithm is used etc.
I guess the other possibility would be to download the firmware from https://software.cisco.com/download/home/286307836 (this page unfortunately requires a login, I don't have the firmware, nor a cisco login, maybe somebody else have and can download/investigate the firmware and if anything is different between these versions etc ... maybe both 1.6 and 1.8.1 would be interesting)...
the last option would be to guess the algorithm, but it could be kind of everything e.g. salted non-iterated hashes or PBKDF2 or even more modern hashing algorithms... several parameters like the iteration count could be unknown and therefore it could be a very difficult guessing gaming (because of this "secret algorithm", obfuscation).
In my opinion the algorithm should be clearly mentioned in the manual/documentation... this is really a bad obfuscation/hiding game of secret (again, I assume that it's really not common knowledge and public what the password hashing algorithm is, I may be wrong... but it doesn't seem that there is much information available online how these 128 bytes are generated)...
I think the first step should be to reach out to some cisco staff and tell them that for compliance/security reasons you need to know how secure this algorithm is and how you can double-check the security by being able to reproduce these password hashing steps.