Understanding the differences between the Cisco password \ secret Types

[Tim Glen]

Best Practices

• The enable password command should no longer be used. Use enable secret instead.
• username joeblow password mypass command should no longer be used.  Use username joeblow secret mypass instead.
• Type 4 Passwords should never be used!
• Type 9 encryption is more resource intensive than Type 8, and both are more intensive than Type 5 (but all operate on an 8xx router fine)
• Use Type 9 if you are able to.   If the IOS you have does not support Type 9 then use Type 7. 

Cisco Password Type’s

Type 4

Cisco created Type 4 around 2013 in an attempt to strengthen password, unfortunately the attempt was severely flawed and resulted in a hash that was weaker than a Type 5 MD5. See the PSIRT below.
Cisco IOS and Cisco IOS XE Type 4 Passwords Issue

Type 5

These use a very simple MD5 hashing algorithm. These are easily reversible with tools on the internet. These should only be used if Type 9 is not available on the IOS version you are running. 

Type 7

These use the Vigenere cipher, a very simple algorithm that was cracked in 1995. These are easily reversible with tools on the internet. These should never be used. 

Type 8

Type 8 passwords are what Type 4 was meant to be, PBKDF2, SHA-256, 80 bit salt, 20,000 iterations. While this is good, it is still vulnerable to brute forcing since AES is easy to implement in graphics cards. I have not proven it but I believe it is possible that the popular tool HashCat is able to decrypt these.

Type 9

These use the SCRYPT hashing algorithm SCRYPT, 80 bit salt, 16384 iterations. It’s expensive to run the algorithm and therefore currently the Best Practice Type password to use. I have not proven it but I believe it is possible that the popular tool HashCat is able to decrypt these.

Please rate or comment to help make this document better!

[kopec2111]

What is the first IOS to support Type 9 hashing?

[ndemers]

Trying to find history of Type 6,8,9 introduction into IOS and IOS-XE.

Main Question : At what point was Type 8 introduced into IOS/IOS-XE code? Some of these features dont support type 8 or 9

Feature	Password Type 6	Password Type 7	Password Type 8	Password Type 9
line con
line vty
bgp neighbor
aaa group server
tacacs-server
radius-server
username
ldp neighbor
ISIS neighbor
snmpv3 community string?
keychain

For reference the command  enable algorithm-type has a history but not the supported algorithms:

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/security/d1/sec-d1-cr-book/sec-cr-e1.html#wp3884449514

enable algorithm-type

To set the algorithm type to hash a user password configured using the enable secret command, use the enable algorithm-type command in global configuration mode. To remove the algorithm type, use the no form of this command.

enable algorithm-type {md5 | scrypt | sha256}

no enable algorithm-type {md5 | scrypt | sha256}
Syntax Description
md5 	

Selects the message digest algorithm 5 (MD5) as the hashing algorithm.
scrypt 	

Selects scrypt as the hashing algorithm.
sha256 	

Selects Password-Based Key Derivation Function 2 (PBKDF2) with Secure Hash Algorithm, 26-bits (SHA-256) as the hashing algorithm.
Command Default

No algorithm type is defined.
Command Modes

Global configuration (config)
Command History
Release 	Modification  15.3(3)M3
This command was introduced.  15.5(1)S
This command was integrated into the Cisco IOS Release 15.5(1)S.