Encryption code

An encryption code, otherwise known as an encryption key or an encryption scheme, is a functional parameter of cryptological encoding used for security purposes.

Cryptological theory
Encryption only enables senders with the appropriate decryption devices to read secretive transmissions or documents. Persons or organizations that do not possess the appropriate decryption key to decrypt an encrypted file must result to a battery of cryptological techniques to decrypt files, even using artificial cognitive computation sources as powerful as smart AIs.

The sender will encrypt a piece and send it to the receiver, and will list both the public key and private key of the file. The public key is widely available, and was used to encrypt the file. The private key is available only to the receiver, and is used to decrypt the file.

The Covenant and the United Nations Space Command both use encryption devices to hide military tactics and orders.

Covenant usage
The Covenant occasionally place advanced encryption on high-importance locked doors within their warships, such as the CCS-class battlecruiser Truth and Reconciliation. During the UNSC raid on the battlecruiser, the Covenant locked the UNSC assault squad in the hangar bays with 128,000-bit modulating encryption until Cortana was able to hack the doors to open and let the UNSC forces venture further into the ship.

UNSC usage
Encryption is placed on UNSC documentation or transmissions in order to maintain the level of secrecy demanded by the Transmission Classification. Encryption codes, like classifications, come in varying types, based on the importance of the information in the file.

Encryption keys

 * None - Transmissions without code are not classified at all and can be accessed by anyone at any time. Examples of this include the journals produced by UNSC Astrophysics.


 * Red - This code is used most of the time in military transmissions. Classification can be "Restricted," "Classified," or "Secret". The code is sometimes harder to crack, depending on how complex the scheme of the code can be. Examples of this code include the Cole Protocol. It was used before or during 2552 to encrypt UNSC Emergency Priority Order 098831A-1.


 * Black - This higher level code is used for more important and urgent information, which can be classified.


 * Gamma - This is one of the highest level codes. It is used on the most classified information and is likely to be an extremely complex code. It coincided with the classification of "Eyes Only Top Secret."

Red

 * file/albatross-seven-lucifer-zeno/
 * file/bravo-tango-beta-five/
 * file/douglas-six-six-lima/
 * file/excised access Omega/
 * file/first light/
 * file/lightning-matrix-four/
 * file/vegas-anaconda-mockingbird-zero/

Black

 * file/delta-charlie-niner/Iona
 * file/gamma-thunder-twelve
 * file/rho-hotel-eight/Iona
 * file/seasonal/
 * file/zulu-oscar-papa/Iona

Unknown

 * file/red rover red rover/

List of appearances

 * Halo: The Fall of Reach
 * Adjunct
 * Halo: Combat Evolved
 * Halo: Combat Evolved Anniversary
 * Halo: Ghosts of Onyx
 * Halo: Blood Line
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * The Impossible Life and the Possible Death of Preston J. Cole