(Tcl) Ed25519 Key Exchange (Shared Secret)

Demonstrates how to create an Ed25519 shared secret for use in key exchange.

Note: This example requires Chilkat v9.5.0.83 or greater.

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load ./chilkat.dll

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

# Alice's private key, a:
#     77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a
# Alice's public key, X25519(a, 9):
#     8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a
# Bob's private key, b:
#     5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6fd1c2f8b27ff88e0eb
# Bob's public key, X25519(b, 9):
#     de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f
# Their shared secret, K:
#     4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742

set alicePrivKey "77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a"
set bobPubKey "de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f"

set privKey [new_CkPrivateKey]

# This example shows only one way of loading an Ed25519 private key.
# Chilkat can load other formats (JWK, PEM, ASN.1 DER, etc.)  
# You may do so by calling LoadAnyFormat or LoadAnyFormatFile.
set success [CkPrivateKey_LoadEd25519 $privKey $alicePrivKey ""]
if {$success == 0} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkPrivateKey $privKey
    exit
}

set pubKey [new_CkPublicKey]

set success [CkPublicKey_LoadEd25519 $pubKey $bobPubKey]
if {$success == 0} then {
    puts [CkPublicKey_lastErrorText $pubKey]
    delete_CkPrivateKey $privKey
    delete_CkPublicKey $pubKey
    exit
}

# Create the shared secret:
set eddsa [new_CkEdDSA]

set sharedSecret [CkEdDSA_sharedSecretENC $eddsa $privKey $pubKey "hexlower"]
if {[CkEdDSA_get_LastMethodSuccess $eddsa] == 0} then {
    puts [CkEdDSA_lastErrorText $eddsa]
    delete_CkPrivateKey $privKey
    delete_CkPublicKey $pubKey
    delete_CkEdDSA $eddsa
    exit
}

puts "Computed: $sharedSecret"
puts "Expected: 4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742"

delete_CkPrivateKey $privKey
delete_CkPublicKey $pubKey
delete_CkEdDSA $eddsa