复旦大学：《密码学基础》课程教学资源（课件讲稿）09-10（2/2）Authentication – Basic protocol constructions – Kerberos

密码学基础09-10 Authentication Basic protocol constructions Kerberos 復大辱软件学院 LiST

LiJT 1 密码学基础 09-10 Authentication – Basic protocol constructions – Kerberos

Outline of talk · Definitions Passwords Unix Passwords One time passwords Challenge-response techniques Basic protocol constructions Alsoone-time Authentication Involving TTP Needham-Schroeder Kerberos 復大辱软件学院 LiST

LiJT 2 Outline of Talk • Definitions • Passwords – Unix Passwords – One time passwords • Challenge-response techniques – Basic protocol constructions – Also “one-time” • Authentication Involving TTP – Needham-Schroeder – Kerberos

Definitions Authentication a claimant tries to show a verifier that the claimant is as declared Identification Entity Authentication 3 復大辱软件学院 LiST

LiJT 3 Definitions Authentication: • A claimant tries to show a verifier that the claimant is as declared – Identification –Entity Authentication

Definitions Claimant(a): The party that claims a certain identity [and provides evidence of possessing the identity] e.g. through possessing a specific secret Verifier( B): The party that verifies the identity of the claimant(accepts or rejects) e.g. through verifying the possession of the secret by claimant 復大辱软件学院 LiST

LiJT 4 Definitions • Claimant (A): The party that claims a certain identity [and provides evidence of possessing the identity] – e.g. through possessing a specific secret • Verifier (B): The party that verifies the identity of the claimant (accepts or rejects) – e.g. through verifying the possession of the secret by claimant

Definitions 单向 Unilatera| authentication 双向 Mutual authentication 5 復大辱软件学院 LiST

LiJT 5 Definitions • 单向 Unilateral authentication • 双向 Mutual authentication

Definitions Data-Origin authentication message authentication Data Integrity Entity Authentication 復大辱软件学院 LiST

LiJT 6 Definitions • Data-Origin Authentication – message authentication • Data Integrity • Entity Authentication

Definitions Data-Origin Authentication Data Integ Early textbooks, viewed these two notions with no essential difference However, two very different notions Auth necessarily involves communications involves identifying the source of a message the most significantly, freshness of a message liveness of the message source message is fresh or not should be determined by apps 復大辱软件学院 LiST

LiJT 7 Definitions • Data-Origin Authentication • Data Integrity – Early textbooks, viewed these two notions with no essential difference – However, two very different notions • Auth. necessarily involves communications • involves identifying the source of a message • the most significantly, freshness of a message; liveness of the message source. – message is fresh or not should be determined by apps

Definitions Data Integrity Entity Authentication Often, a claimed identity in a protocol is a message in its own right. So, confidence about a claimed identity and about the liveness of the claimant can be established by applying data-origin authentication mechanisms 8 復大辱软件学院 LiST

LiJT 8 Definitions • Data Integrity • Entity Authentication – Often, a claimed identity in a protocol is a message in its own right. So, confidence about a claimed identity and about the liveness of the claimant can be established by applying data-origin authentication mechanisms

Authentication scheme · Weak authentication Passwords. pin. etc One-time passwords(semi-strong authentication) Strong(cryptographic)authentication Challenge- Response Mechanisms Zero-knowledge authentication Allow Claimant to demonstrate knowledge of a secret without revealing any information whatsoever of the secret 復大辱软件学院 LiST

LiJT 9 Authentication scheme • Weak authentication – Passwords, PIN, etc – One-time passwords(semi-strong authentication) • Strong (cryptographic) authentication – Challenge – Response Mechanisms • Zero-knowledge authentication – Allow Claimant to demonstrate knowledge of a secret without revealing any information whatsoever of the secret

Outline of talk Definitions Passwords Unix Passwords One time passwords Challenge-response techniques Basic protocol constructions Alsoone-time Authentication Involving TTP 復大辱软件学院 LiST

LiJT 10 Outline of Talk • Definitions • Passwords – Unix Passwords – One time passwords • Challenge-response techniques – Basic protocol constructions – Also “one-time” • Authentication Involving TTP