SCRAM (Salted Challenge Response Authentication Mechanism) Implementation in Go

This repository contains a simple Go implementation of SCRAM, a secure authentication protocol, demonstrating the server and client sides of the authentication process. SCRAM is designed to provide strong security and protection against common authentication vulnerabilities.

SCRAM is a widely used authentication mechanism that employs a combination of cryptographic functions and secure practices to protect user credentials during authentication. It enhances security by using a user-specific salt, iteration count, and cryptographic functions to ensure the confidentiality and integrity of authentication data.

Server Implementation

To create an identity on the server, an administrator creates a user account, specifying the username and plaintext password. The server first applies the key derivation function to compute the SaltedPassword.

SaltedPassword = KeyDerive(password, salt, i)
ClientKey = HMAC(SaltedPassword, "Client Key")
StoredKey = H(ClientKey)
ServerKey = HMAC(SaltedPassword, "Server Key")

• password: is the plaintext password for the user.
• Hash(str): a cryptographic hash function
• HMAC(str, key): hash-based message authentication code
• KeyDerive(str, salt, i): a key derivation function
• i: iteration count, a higher i value increases the cost of a brute-force attack, but also increases the time required for a user to authenticate to the server.
• salt: A per-user randomly generated salt to be used during key derivation. The StoredKey is a cryptographic digest of the ClientKey. The StoredKey is used by the server to verify the client’s identity.

Cited from Kafka authentication using SASL/SCRAM

The server-side implementation includes the following key functionalities:

• User account creation with a randomly generated salt and secure password hashing.
• Sending a "Server First" message to initiate the authentication process, including the user's salt, iteration count, and combined nonce.
• Verification of the client's proof and generation of the server's signature.
• Sending a "Server Final" message that includes the server's signature.

Client Implementation

The client-side implementation includes the following key functionalities:

• Initiation of the authentication process by sending an authentication request to the server.
• Calculation of the client proof and verification of the server's proof.
• Secure handling of user credentials and secure password hashing.

References:

• RFC 5802
• Kafka authentication using SASL/SCRAM