optimisticninja / caencryption

Elementary CA-based encryption algorithm based on paper in references

caencryption

Elementary CA-based encryption algorithm based on paper in references. Reference paper has errors, this is my identification and fixing of errata.

Output of implementation

PLAINTEXT: deadbeefcafebabe
KEY      : f6c78663f3578746
ENCRYPTED: ce09bfd34be8a898
DECRYPTED: deadbeefcafebabe

Rules used

Key Scheduling

Rule 60

Rule 102

Encryption

Rule 15

Rule 170

Decryption

Rule 85

Rule 24

Common (encryption and decryption)

In encryption/decryption round rule chains

Rule 204

For diffusion

Rule 29

Rule 51

Errata from paper

• There are unspecified CA boundaries
• Selected rule 204 is essentially a NOP
• 16x4 bit split in decryption should be 4x6
  • Correct in diagram (figure 3), not algorithm listing (figure 3 in paper, which is 4x16)
• Decryption needs to invert the even/odd segment check
• Rule 153 does not work for the diffusion as it is not reversible, linear rule 29 has been used instead.

References

• Encryption Based on Cellular Automata for Wireless Devices in IoT Environment
• Invertible Wolfram automata