Connecting

Connection is done by many exchanges:

• (Create socket)
• If first byte from server is 0xFF:
  • packet is an ERR_Packet, socket has to be closed
• else
  • Packet is an Initial handshake packet
  • If SSL/TLS connection
    • Client sends SSLRequest packet and switches to SSL mode for sending and receiving the following messages:
  • Client sends Handshake response packet
  • Server sends either:
    • An OK packet in case of success OK_Packet
    • An error packet in case of error ERR_Packet
    • Authentication switch
      • If the client or server doesn't have PLUGIN_AUTH capability:
        • Server sends 0xFE byte
        • Client sends old_password
      • else
        • Server sends Authentication switch request
        • Client may have many exchange with the server according to the Plugin.
      • Authentication switch ends with server sending either OK_Packet or ERR_Packet

Initial Handshake Packet

Client Handshake Response

If the client requests a TLS/SSL connection, first response will be an SSL connection request packet, then a handshake response packet. If no TLS is required, client send directly a handshake response packet.

SSLRequest Packet

ZERO-CONFIGURATION SSL ENCRYPTION

Automatic Encrypted Connections (MariaDB 11.4+):

Previously, failed SSL connections due to self-signed certificates prevented communication. MariaDB 11.4+ introduces a secondary validation method that works for all servers.

What Happens When SSL Validation Fails?

Even without a valid SSL certificate, the connector can still authenticate by remembering the server's fingerprint (unique identifier). However, it needs to confirm the connection is secure.

Verifying a Secure Connection:

The confirmation method depends on the connection type. When using secure MitM-proof methods, like Unix sockets, connector can automatically validate the connection. Otherwise, a shared secret is used.

Shared Secret for Secure Connection:

The shared secret is only used if the authentication plugin password is hashable (e.g., mysql_native_password or client_ed25519) and not empty. It's calculated by hashing the user's hash password with the authentication seed and the server fingerprint.

Server 11.4+ Confirmation Details:

For servers running MariaDB 11.4 or later, the final confirmation packet contains:

• int<1> encryption (actually only 0x01 = SHA256 encryption)
• byte<EOF> shared secret.

Matching the Shared Secret:

If the calculated shared secret matches the received one, the SSL connection is considered valid (host validation is not needed). Otherwise, the connection must be closed for security reasons.

Handshake Response Packet

Server Response to Handshake Response Packet

The server responds with an OK_packet, an ERR_packet or an Authentication Switch Request packet.

Authentication Switch Request

(If client and server support CLIENT_AUTH capability)

Plugin List

mysql_old_password Plugin

deprecated
send a 8 byte encrypted password

authentication plugin data format :

Client response :

mysql_clear_password Plugin

Since password is transmitted in clear, this has be used only when using SSL connection

send clear password to server

Client response :

mysql_native_password Plugin

SHA-1 encrypted password with server seed

authentication plugin data format :

Client response :

The password is encrypted with: SHA1( password ) ^ SHA1( seed + SHA1( SHA1( password ) ) )

dialog Plugin (PAM)

Interactive exchanges to permit fill passwords - for example for 2-Step authentication.

authentication plugin data format :

The server can send one or many requests. For each of them, the client must display this prompt message to the user, to permit the user to type requested information, then send it to the server in string<NUL> format. Password type indicate answer format ( 2 means "read the input with the echo enabled", 4 means "password-like input, echo disabled")

First authentication format (from authentication switch packet) can be empty since 10.4.

This end when server send an EOF_Packet, OK_Packet or ERROR_packet.

auth_gssapi_client Plugin

gssapi implementation

authentication plugin data format :

Client must exchange packet with server until having a mutual GSSAPI authentication. The only difference compared to standard client-server GSSAPI authentication is that exchanges contain standard protocol with packet headers.

client_ed25519 Plugin

The ed25519 plugin uses the Elliptic Curve Digital Signature Algorithm to securely store users' passwords and to authenticate users. It has been Implemented in the server since MariaDB 10.1.22.

See plugin description.

The server sends a random nonce that the client signs.

authentication plugin data format :

Client response :

parsec Plugin

authentication plugin data format :

Client has to send an empty packet to request "ext-salt".

Format of ext-salt is

client must then :

• generate derived key = hash password with PBKDF2 ( sha512 digest) with iteration number and salt from ext-salt.
• generate a client 32 bytes nonce
• generate the signature with ed25519 of an array concatenation of server nonce + client nonce with the generated derived key as private key.

Client response :

Capabilities

Server and Client have different capabilities, here is the possibles values.
client with capabilities CLIENT_MYSQL + CONNECT_WITH_DB will have a value of 9 (1 + 8).

Native Password Authentication

The 20 byte string 'seed' is calculated by concatenating scramble first part (8 bytes) and scramble second part from Initial handshake packet. After that, the client calculates a password hash using the password and seed by using ^ (bitwise xor), + (string concatenation) and SHA1 as follows:

SHA1( passwd) ^ SHA1( seed + SHA1( SHA1( passwd ) ) )