CIAN
Definition
Confidentiality, Integrity, Authentication, Non-repudiation. The four properties a cryptosystem can deliver, usually not all at once with a single primitive. Bulk encryption gives confidentiality; a MAC gives integrity and authentication; a digital signature adds non-repudiation.
- Stands for
- Confidentiality, Integrity, Authentication, Non-repudiation
- Confidentiality tool
- Bulk (symmetric) encryption
- Integrity/authentication tool
- Message authentication code (MAC)
- Non-repudiation tool
- Digital signature
Common questions
Why can't one algorithm deliver all four properties at once?+
Encryption hides content but does not prove who sent it or that it was not altered, and a MAC proves integrity between two parties who share a secret but cannot prove authorship to a third party the way a signature, tied to a private key only one person holds, can.
How does non-repudiation differ from authentication?+
Authentication confirms a message came from a claimed sender to the receiving party, while non-repudiation goes further and gives evidence, verifiable by anyone including a court, that the sender cannot later credibly deny having sent it.
Why does this matter in a forensic digital evidence case?+
An investigator relying on encrypted or signed communications needs to know which of the four properties a given cryptographic mechanism actually proves, since a MAC establishes tamper evidence between two parties but not proof of authorship admissible against a third party.
Related terms
- Asymmetric Key Pair
- Mathematically linked public and private keys. The public key encrypts or verifies, the private key decrypts or signs. Two to three orders...
- Confusion and Diffusion
- Shannon's 1949 design principles. Confusion makes the relationship between key and ciphertext as complex as possible; diffusion spreads each plaintext bit's influence...
- Hybrid Encryption
- The pattern every real protocol uses: asymmetric crypto exchanges a fresh symmetric session key, then the symmetric primitive does the heavy lifting...
- Perfect Forward Secrecy
- A property where compromise of a long-term key does not retroactively break past sessions, because each session used an ephemeral key (typically...
- Symmetric Key
- One shared secret used to both encrypt and decrypt. Fast (AES-128 on AES-NI runs at multiple GB/s) but solves nothing if the...