Скачать презентацию Outline Operational model of encryption Symmetric Скачать презентацию Outline Operational model of encryption Symmetric

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Outline Outline

Operational model of encryption Operational model of encryption

Symmetric key encryption Symmetric key encryption

One-time pad – theoretical vs. practical security One-time pad – theoretical vs. practical security

DES – Data Encryption Standard Initial Permutation DES – Data Encryption Standard Initial Permutation

DES round function F DES round function F

DES key scheduler DES key scheduler

AES – Advanced Encryption Standard AES – Advanced Encryption Standard

General structure of Rijndael encryption/decryption plaintext w[0. . 3] w[4. . 7] w[36. . General structure of Rijndael encryption/decryption plaintext w[0. . 3] w[4. . 7] w[36. . 39] w[40. . 43] ciphertext

Rijndael – Shift row and mix column 2311 1231 x 1123 3112 = Rijndael – Shift row and mix column 2311 1231 x 1123 3112 =

Rijndael – Key expansion Rijndael – Key expansion

RC 4 stream cipher RC 4 stream cipher

Asymmetric key encryption Asymmetric key encryption

RSA (Rivest, Shamir, Adleman, 1978) RSA (Rivest, Shamir, Adleman, 1978)

Proof of RSA decryption Proof of RSA decryption

Proof of RSA decryption cont’d Proof of RSA decryption cont’d

Cryptographic hash functions message of arbitrary length hash function fix length message digest / Cryptographic hash functions message of arbitrary length hash function fix length message digest / hash value / fingerprint

How long should a hash value be? How long should a hash value be?

General structure of hash functions General structure of hash functions

SHA 1 – Secure Hash Algorithm 64 bits length 512 bits SHA 1 – Secure Hash Algorithm 64 bits length 512 bits

SHA 1 compression function f A B C D E SHA 1 compression function f A B C D E

SHA 1 compression function f cont’d SHA 1 compression function f cont’d

SHA 1 compression function f cont’d SHA 1 compression function f cont’d

Block cipher operation modes – ECB Block cipher operation modes – ECB

Block cipher operation modes – CBC Block cipher operation modes – CBC

Block cipher operation modes – CFB initialized with IV shift register (n) select s Block cipher operation modes – CFB initialized with IV shift register (n) select s bits

Block cipher operation modes – OFB initialized with IV shift register (n) select s Block cipher operation modes – OFB initialized with IV shift register (n) select s bits

Block cipher operation modes – CTR Block cipher operation modes – CTR

Enveloping plaintext message bulk encryption key public key of the receiver Enveloping plaintext message bulk encryption key public key of the receiver

Message Authentication Codes (MAC) Message Authentication Codes (MAC)

HMAC HMAC

Digital signatures Digital signatures

“Hash and sign” paradigm private key of sender message hash message signature hash signature “Hash and sign” paradigm private key of sender message hash message signature hash signature public key of sender yes/no

El. Gamal signature scheme El. Gamal signature scheme

El. Gamal signature scheme cont’d El. Gamal signature scheme cont’d

How to establish a shared symmetric key? How to establish a shared symmetric key?

The Wide-Mouth-Frog protocol The Wide-Mouth-Frog protocol

The Needham-Schroeder protocol (1978) The Needham-Schroeder protocol (1978)

Public-key Needham-Schroeder (1978) Public-key Needham-Schroeder (1978)

Diffie-Hellman key exchange (1976) Diffie-Hellman key exchange (1976)

Man-in-the-middle attack Man-in-the-middle attack

Public-key certificates Public-key certificates

Single CA CA Single CA CA

Certificate chains Certificate chains

CA structures CA structures

CA structures cont’d CA structures cont’d

CA structures cont’d CA structures cont’d