This read-create octet string holds the plaintext authentication key inserted into Level 1 and point-to-point hello packets when csIsisCircL1AuthType is set to plaintext, though for security the object always reads back as a zero-length string rather than revealing the configured key. An administrator relies on this to configure a shared secret that all Level 1 neighbors on the circuit must match before an adjacency will form. For example, setting csIsisCircL1Password to a site-specific string on a point-to-point link and configuring the identical string on the far-end router lets the two Level 1 IS-IS neighbors authenticate each other's hellos.