Prefix code

The Prefix Code is a five-digit code unique to each Federation starship.

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Security

Reliant's Prefix Code

If Prefix Codes are still five digits in The Next Generation era and beyond, a brute force attack can allow an attacker to lower a Federation starship's shields, depending on computer security measures. However, the Prefix Code can be disabled by bridge crew with a manual override, or simply altered.

Worf in The Next Generation "The Wounded" exclaimed the Prefix Code would render U.S.S. Phoenix defenseless. This was not the case, as U.S.S. Phoenix subsequently fired and destroyed a Cardassian vessel at range. Therefore, Captain Maxwell either easily disabled the Prefix Code, or the Prefix Code only affects certain ship systems.

Uses of the Prefix Code

Spock transmitting prefix code

The Prefix Code was used by Captain Kirk in The Wrath of Khan as a desperate attempt to gain a temporary tactical advantage against Khan. Khan, without formal training in starship command, was unfamiliar with the prefix code. The code allowed Enterprise to remotely lower Reliant's shields.

In The Next Generation "The Wounded," Picard reveals the Prefix Code of U.S.S. Phoenix to Cardassians.