/CCA2-Hybrid-Encryption

Primary LanguageC

CSC38000 Computer Security

CCA2 Encryption:

Build a public key cryptosystem using a key encapsulation mechanism (KEM)

  • Assymetric System: - RSA - using GMP to operate with arbitrary precision numbers
    • build symmetric system denoted as SKE
      • SKE that works only on buffers
      • SKE that works on files
      • SKE
        • Encryption:
          • 16 byte IV | C = AES(plaintext) | 32byte SHA256 HMAC(C)
          • IV = initialization vectors, unpredictable random number to make sure that when same message is encrypted more than once, the ciphertext is different
        • Decryption:
          1. Check hmac of iv + c
          2. Decrypt ciphertext
    • KEM:
      • combine RSA and SKE on files
      • ciphertext will be:
        • RSA-KEM(x) | SKE ciphertext
        • Generate SKE key with x, where x has as much entropy as the key

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