Authentication Code - Revision history

Tom: /* Solution */

2025-09-06T19:10:49Z

‎Solution

Tom: /* Definition */

2025-09-06T19:08:51Z

‎Definition

Tom: Tom moved page "Authentication Code" to Authentication Code

2025-09-06T19:03:08Z

Tom moved page "Authentication Code" to Authentication Code

Tom at 18:59, 6 September 2025

2025-09-06T18:59:16Z

Tom at 18:58, 6 September 2025

2025-09-06T18:58:16Z

Tom: Created page with "==Definition== https://csrc.nist.gov/projects/message-authentication-codes An authentication code is a short piece of information — usually generated by a cryptographi..."

2025-09-06T18:57:17Z

Created page with "==Definition== https://csrc.nist.gov/projects/message-authentication-codes An **authentication code** is a short piece of information — usually generated by a cryptographi..."

New page

==Definition==

https://csrc.nist.gov/projects/message-authentication-codes

An **authentication code** is a short piece of information — usually generated by a cryptographic algorithm — that proves a message or transaction is genuine and hasn’t been altered.

In formal cryptography terms, it’s most often a **Message Authentication Code (MAC)**:

- **Definition (NIST)**: A **keyed cryptographic checksum** based on an approved security function.
- **Purpose**:
1. **Authenticity** — Confirms the message came from the claimed sender.
2. **Integrity** — Confirms the message wasn’t changed in transit.
==Solution==
1. Sender and receiver share a **secret key**.
2. Sender runs the message + key through a MAC algorithm to produce the authentication code (tag).
3. Receiver runs the same algorithm with the same key; if the tag matches, the message is accepted as authentic.
- **Security property**: Without the secret key, it should be computationally infeasible to forge a valid code for any new message.

===Example in practice===
- In HTTPS, TLS uses MACs (or AEAD modes with built‑in authentication) to ensure that encrypted packets haven’t been tampered with.
- In APIs, an authentication code might be an HMAC (Hash‑based MAC) attached to each request.

==References==

[[Category: Glossary]]
[[Category: Authentication]]

@@ Line 16: / Line 16: @@
 . Sender runs the message + key through a MAC algorithm to produce the authentication code (tag).
 . Receiver runs the same algorithm with the same key; if the tag matches, the message is accepted as authentic.
-- **Security property**: Without the secret key, it should be computationally infeasible to forge a valid code for any new message.
+*Security property: Without the secret key, it should be computationally infeasible to forge a valid code for any new message.
 ===Example in practice===
 * In HTTPS, TLS uses MACs (or AEAD modes with built‑in authentication) to ensure that encrypted packets haven’t been tampered with.
 * In APIs, an authentication code might be an HMAC (Hash‑based MAC) attached to each request.
 ==References==

@@ Line 7: / Line 7: @@
 In formal cryptography terms, it’s most often a **Message Authentication Code (MAC)**:
-- **Definition (NIST)**: A **keyed cryptographic checksum** based on an approved security function.
+*Definition (NIST): A **keyed cryptographic checksum** based on an approved security function.
-- **Purpose**:
+*Purpose
 . **Authenticity** — Confirms the message came from the claimed sender.
 . **Integrity** — Confirms the message wasn’t changed in transit.
 ==Solution==
 . Sender and receiver share a **secret key**.

← Older revision	Revision as of 19:03, 6 September 2025
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@@ Line 3: / Line 3: @@
 https://csrc.nist.gov/projects/message-authentication-codes
-An **authentication code** is a short piece of information — usually generated by a cryptographic algorithm — that proves a message or transaction is genuine and hasn’t been altered.
+An [[Authentication Code]] is a short piece of information — usually generated by a cryptographic algorithm — that proves a message or transaction is genuine and hasn’t been altered.
 In formal cryptography terms, it’s most often a **Message Authentication Code (MAC)**: