Diffie and Hellman in 1976 based on mathematical functions asymmetric uses two

Diffie and hellman in 1976 based on mathematical

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Diffie and Hellman in 1976 based on mathematical functions asymmetric uses two separate keys public key and private key public key is made public for others to use some form of protocol is needed for distribution 2017 컴퓨터보안
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52 plaintext readable message or data that is fed into the algorithm as input encryption algorithm performs transformations on the plaintext public and private key pair of keys, one for encryption, one for decryption ciphertext scrambled message produced as output decryption key produces the original plaintext 2017 컴퓨터보안
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53 Table 2.3 Applications for Public - Key Cryptosystems 2017 컴퓨터보안
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54 computationally easy to create key pairs computationally easy for sender knowing public key to encrypt messages computationally easy for receiver knowing private key to decrypt ciphertext computationally infeasible for opponent to determine private key from public key computationally infeasible for opponent to otherwise recover original message useful if either key can be used for each role 2017 컴퓨터보안
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55 RSA ( Rivest , Shamir, Adleman ) developed in 1977 most widely accepted and implemented approach to public- key encryption block cipher in which the plaintext and ciphertext are integers between 0 and n -1 for some n . Diffie - Hellman key exchange algorithm enables two users to securely reach agreement about a shared secret that can be used as a secret key for subsequent symmetric encryption of messages limited to the exchange of the keys Digital Signature Standard (DSS) provides only a digital signature function with SHA-1 cannot be used for encryption or key exchange Elliptic curve cryptography (ECC) security like RSA, but with much smaller keys 2017 컴퓨터보안
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56 RSA Public-Key Encryption by Rivest, Shamir & Adleman of MIT in 1977 best known and widely used public-key algorithm uses exponentiation of integers modulo a prime encrypt: C = M e mod n decrypt: M = C d mod n = ( M e ) d mod n = M both sender and receiver know values of n and e only receiver knows value of d public-key encryption algorithm with public key PU = { e , n } and private key PR = { d , n }. 2017 컴퓨터보안
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57 RSA Algorithm
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58 RSA Example 2017 컴퓨터보안
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59 Security of RSA trying all possible private keys defense is to use a large key space, however this slows speed of execution brute force several approaches, all equivalent in effort to factoring the product of two primes mathematical attacks depend on the running time of the decryption algorithm comes from a completely unexpected direction and is a ciphertext-only attack countermeasures: constant exponentiation time, random delay, blinding timing attacks attack exploits properties of the RSA algorithm chosen ciphertext attacks 2017 컴퓨터보안
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60 Table 21.2 Progress in Factorization 2017 컴퓨터보안
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61 Diffie-Hellman Key Exchange first published public-key algorithm by Diffie and Hellman in 1976 along with the exposition of public key concepts used in a number of commercial products practical method to exchange a secret key securely that can then be used for subsequent encryption of messages security relies on difficulty of computing discrete logarithms 2017 컴퓨터보안
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62 Diffie-Hellman Key Exchange Algorithm
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