Blockchain tutorial 6: Digital signature

This is part 6 of the Blockchain tutorial explaining what a digital signature is. In this video series different topics will be explained which will help you to …


  1. In 2:24, he says the data which is the document is now hashed which gives hash value for comparison. My question is how Bob has the actual data? wasn't he supposed to be the receiver? According to the explanation, so-far he has only decrypted the digital signature which gave him the original hash value which is not the actual data. Can someone please explain.
    Thank you!

  2. How come sometimes I need to import Crypto and sometimes I don't? i.e. sometimes just the "from Crypto.Hash import RSA" works without importing Crypto and sometimes I do have to import Crypto. Also curious why don't you use RSA 2048 instead of 1024? Isn't it more secure?

  3. Different different algorithms (MD5 and sha1) give same hash function ? While checking (encryption and decryption) digital signature.? Is it possible if encryption with MD5 and decryption with sha1 algorithms ?
    Thanks for your tutorial.

  4. Hi, this tutorial on digital signature is getting into the complex part of block chain. Tutorial 6 needs to be view several times for a proper understanding. Not easy, but it's intriguing. Thanks for the tutorial.

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