Implementing-cryptography-using-python

Chapter 8 ■ Cryptographic Applications and PKI 243
B: The second user (Bob), receives the key from Alice and uses it to generate
a secret key; this gives both users the same secret key to encrypt.
Examine Figure 8.7x to see how the points intersect with the ECC.
Figure 8.7: Point intersection of ECC curve
To get a better understanding, review the following five steps:
1. Alice and Bob get public numbers P = 23, G = 9.
2. Each user selects a private key:
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Alice selected a private key a = 4
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Bob selected a private key b = 3
3. Each user computes public values:
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Alice: x = (9^4 mod 23) = (6561 mod 23) = 6
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Bob: y = (9^3 mod 23) = (729 mod 23) = 16
4. Alice and Bob exchange public numbers:
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Alice receives public key y = 16
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Bob receives public key x = 6
5. Alice and Bob compute symmetric keys:
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Alice: ka = y^a mod p = 65536 mod 23 = 9
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Bob: kb = x^b mod p = 216 mod 23 = 9