從泛民初選 探討Hash保安

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從泛民初選 探討Hash保安

  1. 1. 從泛民初選 探討HASH保安
  2. 2. Hash Function Can be applied to a block of data of any size ●produce a fixed-length output ●relatively easy to compute of any given value, making both hardware and software implementations practical ●
  3. 3. Hash Function For any given hash code h, it is computationally infeasible to find x such that H(x) = h. We called it one-way property ●
  4. 4. Hash Function For any given block x, it is computationally infeasible to find y <> x with H(y) = H(x). This is referred to as weak collision resistance. ●
  5. 5. Hash Function It is computationally infeasible to find any pair (x, y) such that H(x) = H(y). It is referred to as string collision resistance. ●
  6. 6. Usage Password Protection ●As a fingerprint of a message, data or file (Checksum) ●Data Normalization (ID Generation) ●
  7. 7. Common Cracking Pattern Finding ●Birthday Attack ●Dictionary Attack ●
  8. 8. Solution publish the method and open the source for all people to review. ●increase the length of the hash code. ●add salt ●
  9. 9. Possible Cracking of HKID Hash Code Server had been cracked ●Dictionary Attack ●man in middle (Depends on the Design) ●Virus ●Key Logger ●Binary or source code disclose ●
  10. 10. Workshop openssl ●md5sum ●shasum ●Fun on cracking my 30000 hash codes ●

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