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Cryptographic Hash Functions Message Authentication Digital Signatures

Cryptographic Hash Functions Message Authentication Digital Signatures. Abstract. We will discuss Cryptographic hash functions Message authentication codes HMAC and CBC-MAC Digital signatures. Encryption/Decryption. Provides message confidentiality .

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Cryptographic Hash Functions Message Authentication Digital Signatures

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  1. Cryptographic Hash FunctionsMessage AuthenticationDigital Signatures

  2. Abstract We will discuss • Cryptographic hash functions • Message authentication codes • HMAC and CBC-MAC • Digital signatures

  3. Encryption/Decryption • Provides message confidentiality. • Does it provide message authentication?

  4. Collision-resistant hash functions can be built from collision-resistant compression functions using Merkle-Damgard construction.

  5. Merkle-Damgard Construction m1 m2 m3 mk v0 v1 v2 vk h(m) … f f f f IV

  6. m = m1 m2 m3 ms Xhk(m) h(m) … f f kX f f IV ms+1 f hk(m) hk(m||ms+1)

  7. Cipher Block Chaining (CBC)

  8. Message m MACk(m) Message m Sigpr(m)

  9. Encryption (using RSA): Bob Alice PRBob PUBob E C D M M Digital signature (using RSA-1): Bob Alice PRBob PUBob E(S) =M? E S D M Verify Sign

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