Tổng hợp tài liệu, ebook Công Nghệ Thông Tin tham khảo.
most promising approach to improving password security allow users to select own password but have system verify it is acceptable ▫ simple rule enforcement (see earlier slide) ▫ compare against dictionary of bad passwords ▫ use algorithmic (markov model or bloom filter) to detect poor choices
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Internet Security Association and Key Management Protocol provides framework for key management defines procedures and packet formats to establish, negotiate, modify, & delete SAs independent of key exchange protocol, encryption alg, & authentication method
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merchant sends payment gateway a payment capture request gateway checks request then causes funds to be transferred to merchants account notifies merchant using capture response
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Does not rely on certificate authorities in PGP every user is own CA ▫ can sign keys for users they know directly (certificates are like X.509) forms a “web of trust” ▫ trust keys have signed ▫ can trust keys others have signed if have a chain of signatures to them key ring includes trust indicators users can also revoke their keys
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(Step 1) Key generation: Every entity generates a public-private key pair ▫ choose a random private key ▫ compute the public key (Step 2) Registration: Every entity should ▫ provide proof of their identity (to the CA) (Step 3) Obtain certificate from the CA ▫ CA signs a certificate which binds the identity of A to A’s public key
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Sheart of the algorithm processing message in 1024-bit blocks consists of 80 rounds ▫ updating a 512-bit buffer ▫ using a 64-bit value Wt derived from the current message block ▫ and a round constant based on cube root of first 80 prime numbers
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Based on the difficulty of discrete log problem (like DH) All entities agree on a prime p (say 200 digits long) and a generator g Alice chooses a random value a as her private key (a < p also has typically the same number of digits as p) Alice compute α = ga mod p as her public key
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Shave considered: ▫ Symmetric cipher model and terminology ▫ Classical ciphers ▫ Modern cipher techniques block vs stream ciphers Feistel cipher design & structure DES details & strength ▫ Differential & Linear Cryptanaly
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Symmetric Cipher Model Classical Substitution Ciphers ▫ Caesar Cipher ▫ Monoalphabetic Cipher ▫ Playfair Cipher ▫ Polyalphabetic Ciphers ▫ Vigenère Cipher Cryptanalysis using letter frequencies
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DoS attack or DDoS is an attempt to make a computer resource unavailable to its intended users. Methods of attack ▫ ICMP flood ▫ Teardrop Attacks ▫ Peer-to-peer attacks
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