Almost all passwords and other authentication strings in Cisco IOS configuration files are encrypted using the weak, reversible scheme used for user passwords.
To determine which scheme has been used to encrypt a specific password, check the digit preceding the encrypted string in the configuration file. If that digit is a 7, the password has been encrypted using the weak algorithm. If the digit is a 5, the password has been hashed using the stronger MD5 algorithm.
For example, in the configuration command:
enable secret 5 $1$iUjJ$cDZ03KKGh7mHfX2RSbDqP.
The enable secret has been hashed with MD5, whereas in the command:
username www.kashu.org password 7 07362E590E1B1C041B1E124C0A2F2E206832752E1A01134D
The password has been encrypted using the weak reversible algorithm.