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Service password-encryption command

As explained in Acing the CCNA Exam: Volume 2 Advanced Networking and Security

service password-encryption is a Cisco IOS configuration command that applies reversible obfuscation to configured plaintext passwords.

service password-encryption applies weak, reversible encryption to the enable password and other configured passwords. Cisco identifies the resulting credentials as type 7. Unlike hashing, encryption can be reversed, and type 7 passwords can be easily decrypted with free online tools. section 11.3.1

Use these distinctions when configuring Cisco IOS passwords:

  • enable password stores a type 0 password in cleartext unless service password-encryption is applied. section 11.3.1
  • service password-encryption changes such passwords to type 7, but does not provide secure, irreversible storage. section 11.3.1
  • Prefer enable secret, which stores a secure hash using a supported algorithm such as MD5, SHA-256, or scrypt. section 11.3.1

How Acing the CCNA Exam: Volume 2 Advanced Networking and Security covers it

How deep it goes
Defines type 0 and type 7 behavior and contrasts reversible encryption with hashing, but does not explain the encryption algorithm internals.
Examples
Uses enable password password and service password-encryption to contrast cleartext type 0 with reversible type 7 storage.
What it assumes
Assumes familiarity with Cisco IOS password commands and teaches the difference between cleartext, encryption, and hashing.
What you can do after
Configure reversible password obfuscation while recognizing why enable secret is the preferred secure alternative.
How it connects
Connects enable password, enable secret, username, hashing, encryption, and Cisco IOS password storage.
Cover of Acing the CCNA Exam: Volume 2 Advanced Networking and Security
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