(CkPython) How to Generate an Elliptic Curve Shared Secret

Demonstrates how to generate an ECC (Elliptic Curve Cryptography) shared secret. Imagine a cilent has one ECC private key, the server has another. A shared secret is computed by each side providing it's public key to the other. The private keys are kept private.

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import sys
import chilkat

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# This example includes both client-side and server-side code.
# Each code segment is marked as client-side or server-side.
# Imagine these segments are running on separate computers...

# -----------------------------------------------------------------
# (Client-Side) Generate an ECC key, save the public part to a file.
# -----------------------------------------------------------------
prngClient = chilkat.CkPrng()
eccClient = chilkat.CkEcc()
# privKeyClient is a CkPrivateKey
privKeyClient = eccClient.GenEccKey("secp256r1",prngClient)
if (eccClient.get_LastMethodSuccess() != True):
    print(eccClient.lastErrorText())
    sys.exit()

# pubKeyClient is a CkPublicKey
pubKeyClient = privKeyClient.GetPublicKey()
pubKeyClient.SavePemFile(False,"qa_output/eccClientPub.pem")

# -----------------------------------------------------------------
# (Server-Side) Generate an ECC key, save the public part to a file.
# -----------------------------------------------------------------
prngServer = chilkat.CkPrng()
eccServer = chilkat.CkEcc()
# privKeyServer is a CkPrivateKey
privKeyServer = eccServer.GenEccKey("secp256r1",prngServer)
if (eccServer.get_LastMethodSuccess() != True):
    print(eccServer.lastErrorText())
    sys.exit()

# pubKeyServer is a CkPublicKey
pubKeyServer = privKeyServer.GetPublicKey()
pubKeyServer.SavePemFile(False,"qa_output/eccServerPub.pem")

# -----------------------------------------------------------------
# (Client-Side) Generate the shared secret using our private key, and the other's public key.
# -----------------------------------------------------------------

# Imagine that the server sent the public key PEM to the client.
# (This is simulated by loading the server's public key from the file.
pubKeyFromServer = chilkat.CkPublicKey()
pubKeyFromServer.LoadFromFile("qa_output/eccServerPub.pem")
sharedSecret1 = eccClient.sharedSecretENC(privKeyClient,pubKeyFromServer,"base64")

# -----------------------------------------------------------------
# (Server-Side) Generate the shared secret using our private key, and the other's public key.
# -----------------------------------------------------------------

# Imagine that the client sent the public key PEM to the server.
# (This is simulated by loading the client's public key from the file.
pubKeyFromClient = chilkat.CkPublicKey()
pubKeyFromClient.LoadFromFile("qa_output/eccClientPub.pem")
sharedSecret2 = eccServer.sharedSecretENC(privKeyServer,pubKeyFromClient,"base64")

# ---------------------------------------------------------
# Examine the shared secrets.  They should be the same.
# Both sides now have a secret that only they know.
# ---------------------------------------------------------
print(sharedSecret1)
print(sharedSecret2)