Remote Access Authentication: PAP and CHAP#

This blog article will discuss two username/password authentication protocols: Password Authentication Protocol and The Challenge Handshake Authentication Protocol. By the completion of this page, you’ll know if you should use one of two methods for authentication of point-to-point packets.

Introduction#

Most networks need you to recognize with some sort of input such as a user name and a password. Depending on the network operating system, the specific technique of username/password authentication differs. Here is what it contains in general:

Encryption: This approach scrambles a password, making it unreadable to anybody who monitors storage or communications.

Response and challenge: Response and challenge demand you to verify your credentials at the start of the transaction.

When a user wants to access, CHAP creates a problem. If the user correctly replies to the challenge, the access request is approved. CHAP increases overall security by encrypting message exchanges.

Password Authentication Protocol#

Password Authentication Protocol (PAP) requires the user to provide a username and password, which are then compared to data recorded in a table to check if they match. PAP is quite similar to the traditional Unix login. It uses a two-way handshake.

PAP sends authentication credentials in plaintext. There is no encryption or extra protection for the data you submit using this Password Authentication Protocol.

The Challenge Handshake Authentication Protocol#

  • CHAP was developed to enhance the security of the verification procedure. The Challenge Handshake Authentication Protocol is one approach for protecting information while utilizing remote access to a resource.

  • CHAP is a remote access authentication protocol that works in combination with the PPP to offer security and authentication to distant resource users.

  • CHAP works in tandem with PPP to safeguard the credentials supplied for authentication and to validate the connection to a legitimate resource.

  • CHAP can also be set to use one-way reversible encryption, which employs the one-way hash, to store a password. The password is therefore safeguarded. However, CHAP is superior to Password Authentication Protocol since it broadcasts passwords over the network in cleartext.

CHAP three-way handshake#

CHAP uses a three-way handshake to authenticate the identity of the peer on a regular basis.

1-) The authenticator (generally a network server) transmits a note to the peer. This challenge contains an ID and a casual number. They also transfer a predetermined secret word, phrase, or value.

2-) The peer combines together the random value, the ID, and the secret creating a hash function. It transmits this new value to the authenticator server.

3-) The authenticator also generates a hash in the same way. Then it compares the answer to its own hash value. If the hashes correspond, the authentication is accepted; if not, the connection is closed.

To strengthen security, the authenticator can be programmed to repeat the authentication process throughout the conversation session, and repeat the challenge-response procedure. The authenticator sends a fresh challenge to the peer at random intervals and repeats steps one through three.

Security considerations with PAP and CHAP#

  • It does not use encrypted password databases and hence provides less protection than other levels of authentication.

  • The shared secrets may be kept as cleartext on both ends, leaving the secret subject to compromise or discovery.

  • PAP sends unencrypted credentials during authentication, while CHAP has major security weaknesses that make obtaining the credentials uncomplicated.

  • MS-CHAP v2 provides much greater security than PAP and CHAP, however, it is also known to be susceptible with no effort and should be avoided wherever feasible.

  • With PPTP VPNs, PAP, CHAP, and MS-CHAP v2 are utilized. However, for increased protection, you can consider utilizing another VPN type. Unfortunately, MS-CHAP and MS-CHAP v-2 are also vulnerable. Many people have abandoned MS-CHAP in favor of L2TP, IPsec, or another sort of secure VPN connection.

See also

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