消息摘要和數(shù)字簽名-文庫吧
2025-04-20 05:38 本頁面
【正文】 PE項目的結(jié)果 RIPEMD為 128位 更新后成為 RIPEMD160 基礎(chǔ)是 MD5 ?MD5 Ron Rivest于 1990年提出 MD4 1992年 , MD5 (RFC 1321) developed by Ron Rivest at MIT MD5把數(shù)據(jù)分成 512bit塊 MD5的 hash值是 128bit 在最近數(shù)年之前 ,MD5是最主要的 hash算法 現(xiàn)行美國標(biāo)準(zhǔn) SHA1以 MD5的前身 MD4為基礎(chǔ) 王小云對 MD5的攻擊 ?方法： 差分攻擊 模整數(shù)減法 異或運算 王小云對 MD5的攻擊 ?目的：尋找如下條件的消息： (a, b, c, d) = MD5(a0, b0, c0, d0,M0), (a’, b’, c’, d’) = MD5(a0, b0, c0, d0,M0’ ), MD5(a, b, c, d,M1) = MD5(a’, b’, c’, d’,M1’ ) ?2021年的攻擊結(jié)果 找到 (M0,M0’ )需要 239 次 MD5操作 , IBM P690上需要時間 15分到 1小時 找到 (M1,M1’)需要 232 次 MD5操作 , IBM P690上需要時間 5分到 15分 The Story of Alice and her Boss ? Caesar39。s View ? At the day Alice is supposed to leave, Caesar writes a letter of remendation for Alice on paper. The same day, she asks Caesar to digitally sign the letter. For his convenience she presents an electronic copy of the document. Caesar opens the document it looks exactly like the original document. So he signs the document. ? Months later, Caesar discovers that there has been a breach of secrecy with his French affair files. Will he ever find out who tricked him and how? The Story of Alice and her Boss ? Alice39。s View ? Being an intern, Alice does not have any access to secret documents. Not enough for her ... ? ... tricky Alice decides to fool Caesar. Because Caesar is still relying on the widely used MD5 hash function, she implements the attack from Wang and Yu [How to break MD5 and other hash functions. Eurocrypt 2021 ] to find MD5 collisions. When she receives her letter of remendation (on paper), she prepares two postscript files with the same MD5 hash: ? One to display the letter of remendation, and ? a second one, an order from Caesar to grant Alice some kind of a security clearance. The Story of Alice and her Boss a25f7f0b 29ee0b39 68c86073 8533a4b9 數(shù)字簽名 ?數(shù)字簽名是手寫簽名的數(shù)字相似物。消息的數(shù)字簽名其實是一個數(shù)值，它依賴于只有簽名者知道的某個秘密數(shù)和待簽的消息內(nèi)容。數(shù)字簽名應(yīng)具有如下性質(zhì) ? 能夠驗證簽
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