This is the second building block of cryptocurrency and is digitally analogous to the hand written signatures that we usually make.

The properties of the digital signature are as follows:

• You can create your own signatures, but they can be verified by another person too
• The signature is tied to a particular document or message so that it cannot be used again and again for different documents and messages

Let's now look at an example of a digital signature in the following diagram:

Let's take an example and say that there is a string in the document which states that "I agree to pay $5000 for the software". Since this is the document that is being signed, we first apply a hash function to it. It gives us a hash or digest of the document, which is again fixed in size. Then, we apply our private key, or a specific key, to encrypt it and we get the outcome as a digital signature. This digital signature is signed specifically for this input, which states that "I agreed to pay $5,000 for the software".

Here, we saw how cryptography and cryptocurrency are digital assets that are widely used. We also saw how cryptocurrency uses cryptography and its techniques, such as hash functions and digital signatures.