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Update README.MD

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Bill Buchanan
2023-02-23 16:46:28 +00:00
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unit05_key_exchange/lab/README.MD
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@@ -367,6 +367,7 @@ print("Alice's derived key: ",binascii.b2a_hex(Alice_derived_key).decode())())
Now modify the code to implement the SECP192R1 and also for the SECP521R1 curve. What do you notice about the sizes of the keys created between the different curve types?
### D.2
The code to implement Curve 25519 for key exchange (X25519) is:
```python
@@ -415,11 +416,11 @@ A sample of this is [here](https://asecuritysite.com/hazmat/hashnew29).
Do Bob and Alice end up with the same key?
The public key starts with a "30" or a "20", but the ECDH method used a public key with a "40" at the start. Which is the different between these public key forms?
If you change the "DER" to "PEM" how does it change the viewing of the keys (remember to remove binascii.b2a_hex() method)?
### D.2
We used Curve 25519 in D.1. Can you modify the code so that it uses secp256k1? The code for secp256k1 is defined in the secp256k1.py file [here](https://asecuritysite.com/encryption/python_secp256k1ecdh2).
## E Simple Key Distribution Centre (KDC)
Rather than using key exchange, we can setup a KDC, and where Bob and Alice can have long-term keys. These can be used to generate a session key for them to use. Enter the following Python program, and prove its operation: