Security Access Codes
Access to all Starfleet computer systems is highly regulated. A standard set of authorization codes have been programmed into the starboard and engineering computer cores of all ships in order to stop any undesired access to the systems.
 
Alpha-Two
Unlimited access to all ship's records, systems, commands and computers. 

Alpha-One
Unlimited access to all ship's records, systems and computers. No access to ship localized command functions. 

Beta-Two
Unlimited access to all ship's records, systems and computers. Limited access to command functions (except if stated otherwise by Commanding Officer). 

Beta-One
Unlimited access to all ship's records, and computers. Limited access to command functions (except if stated otherwise by Commanding Officer). Access to ship systems is limited to duty related functions. 

Delta-Two
Limited access to all ship's records, systems, commands and computers. Access Limited to duty related functions. 

Delta-One
Limited access to all ship's records, and computers. Access limited to job related functions.

Different officers on a starfleet vessel, have varying levels of security access, depending on their level of authority or their duties. The following common positions, have been assigned standard levels of security access. The final decision on an officers level of security access, however, is decided by that officer's Commanding Officer. 
The Commanding Officer reserves the previlege of permitting limited access to any unspecified section of the ship to any personnel whose functions, in the eyes of the CO, require it. 
 

Position Access Level
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Commanding Officer Alpha-Two
Executive Officer Alpha-Two
Chief Operations Officer Alpha-One
Intelligence Officer Beta-Two
Chief Medical Officer Beta-One
Mission Operations Officer Beta-One
Chief Engineering Officer Beta-Two
Tactical Officer Beta-One
Flight Control Officer Beta-One
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Data Access Levels

Access to all Starfleet data is highly regulated. A standard set of access levels have been programmed into the starboard and engineering computer cores of all ships in order to stop any undesired access to confidential data.

The access levels are as follows:

Level 5
Unlimited access to all classified, secret, top-secret, ultra-secret Starfleet or Federation documents and records. 

Level 4
Limited access to all classified, secret, top-secret Starfleet or Federation documents and records. Access is limited on a 'need to know' basis.

Level 3
Limited access to all classified and secret Starfleet or Federation documents and records. Access is limited on a 'need to know' basis. 

Level 2
Limited access to all Starfleet or Federation documents and records. Access is limited on a 'need to know' basis. 

Level 1
Limited access to Starfleet or Federation documents and records. Access is limited to job related elements.

The following guidelines have been set as standard, by Starfleet Command:
 
Starfleet Rank Access Level
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Admirals and Commodores Level 5
Captains, Commanders and certain specific personnel (duty related) Level 4
Lieutenants, Lieutenants (j.g.) and certain specific personnel (duty related) Level 3
All personnel in operational duties Level 2
All personnel and civilians in Starfleet service Level 1
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Other Starfleet Security Codes & Protocols

Blue Alert
Aboard Federation starships with the ability of planetfall, blue alert is a state of readiness for landing operations. Blue alert notifies the ship's crew to occupy Code Blue stations, and is ordered prior to the starship's landing on a planet and prior to liftoff. A starship commander should not order the start of descent until all decks report that condition blue has been set. 

Code 1
Starfleet designation for a declaration of war. In 2267 the Enterprise received a Code 1 message from Starfleet Command stating they were at war with the Klingon Empire. The starship then proceeded to Organia, where the Klingons were expected to strike.
See also: Code Factor 1 

Code 1 Emergency
Federation signal for a total disaster, requiring an immediate response, also designated as a Priority 1 call. 

Code 2
Starfleet encryption protocol. 

Code 47
Term designating a Starfleet subspace communiqué of extremely high sensitivity or secrecy. 

Code 710
Interstellar code prohibiting a spacecraft from approaching a planet. 

Code Factor 1
Starfleet code meaning invasion status. 

Code One Alpha Zero
Signal indicating the discovery of a space vehicle in distress. 

Coded Transponder Frequency
A specific subspace frequency and code that activated a starship's transponder to send back its identifying code, permitting allied vessels and authorities to accurately track the ship. 

Condition Green
Covert Starfleet code used to secretly indicate on a clear channel that the speaker is being held captive. 

Fractal Encryption
Very sophisticated, virtually unbreakable computer encryption technique.   

Phase 1 Search
Standard Starfleet procedure for a painstaking search aboard a ship for an individual presumed injured and unable to respond. 

Prefix Code
In a Federation starship's computer systems, the prefix code was a security passcode appended to computer commands to prevent unauthorized activation or control of key systems. 

Red Alert
Aboard Federation starships and other vessels, a state of maximum crew and systems readiness. 

Transporter Code 14
Command for an object to be dematerialized, then immediately re-materialized in a dissociated condition, effectively destroying the object. 

User Code Clearance
A code required to access the control systems of a starship. 

Yellow Alert
A state of significantly increased readiness aboard Federation starships and other vessels.