Red/black concept

The red / black concept (German red / black concept) describes a secure foreclosure in cryptographic environments between the unencrypted (plain text ) sensitive or classified information (red signal / red signals ) of the encrypted information, also called ciphertext (black signal / black ) signals.

In NSA jargon encryption devices are often called " Blacker " because they convert red ( unencrypted ) data in black (encrypted) signals. The TEMPEST Standard requires a minimum screen or a physical minimum distance between cables or hardware for Red and black signals in NSTISSAM Tempest/2-95.

Different organizations have different requirements for the separation of red and black fiber optic cables. The Red / Black terminology is also used in the field of cryptographic keys:

• Black keys were in turn encrypted with a Key Encryption Key ( KEK ) and are therefore safe.
• Red keys are not encrypted and therefore must be regarded as highly sensitive material.