电子商务信息安全与管理 全套课件(英文版双语教学使用）.PPTVIP

* AH中完整性检查包括哪些数据？ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * AH中完整性检查包括哪些数据？ * Can see SHA shares much in common with MD4/5, but with 20 instead of 16 steps in each of the 4 rounds. Note the 4 constants are based on sqrt(2,3,5,10). Note also that instead of just splitting the input block into 32-bit words and using them directly, SHA-1 shuffles and mixes them using rotates XOR’s to form a more complex input, and greatly increases the difficulty of finding collisions. * This key setup is done once (rarely) when a user establishes (or replaces) their public key. The exponent e is usually fairly small, just must be relatively prime to ?(N). Need to compute its inverse to find d. It is critically important that the private key KR={d,p,q} is kept secret, since if any part becomes known, the system can be broken. Note that different users will have different moduli N. * Here walk through example using “trivial” sized numbers. Selecting primes requires the use of primality tests. Finding d as inverse of e mod ?(n) requires use of Inverse algorithm (see Ch4) * Can show that RSA works as a direct consequence of Euler’s Theorem. * * * * * * * * * * * * * * * * * * * * * * * * * * * * Cryptographic Computations Master Secret Creation – two stages: pre-master-secret exchange (RSA or Diffie-hellman) and master secret computation by both sides Generation of Cryptographic Parameters – the master-secret is a seed value for functions that generate the client/server MAC secret, keys, and IV Transport Layer Security TLS is an Internet standard to replace SSLv3 Defined in RFC 2246 Record format is the same as SSL Record Format TLS makes use of HMAC (padding bytes are XORed) Transport Layer Security PRF, pseudorandom function, expands small shared secrets into longer blocks of data. Uses two hash functions (RSA SHA-1) for added security Similar alert codes to SSL with a few new additions Cipher suites are the same except for For