def DeriveECDHSecret(privateKey, publicKey):
"""Generate a shared secret from keys in byte format."""
derive = ECDH(curve=NIST256p)
derive.load_private_key_bytes(unhexlify(privateKey))
derive.load_received_public_key_bytes(unhexlify(publicKey))
secret = derive.generate_sharedsecret_bytes()
return secret
print(f"ECDSA Public key:\n\t" + x.decode("utf-8") + "." + y.decode("utf-8") +
"\n\t" + data['pub'])
# 3. Check Verification method
x, y = data["pub"].split('.')
vpub = base64.b64decode(base64urldecode(x)) + base64.b64decode(
base64urldecode(y))
vpub = VerifyingKey.from_string(vpub, curve=NIST256p, hashfunc=sha256)
integrity = sha256(signed['m'].encode('utf-8'))
print(
f'Verify signature: {vpub.verify(base64.b64decode(signed["s"]), integrity.digest(), hashfunc=sha256)}'
)
# ECDH
epriv = base64urldecode(data["epriv"])
epriv = base64.b64decode(epriv)
# 1. Decode k
ecdh = ECDH(curve=NIST256p)
k = ecdh.load_private_key_bytes(epriv)
# 2. Generate public key
epub = k.to_string()
ex, ey = epub[:32], epub[32:]
ex = base64urlencode(base64.b64encode(ex))
ey = base64urlencode(base64.b64encode(ey))
print(f"ECDSA Public key:\n\t" + ex.decode("utf-8") + "." +
ey.decode("utf-8") + "\n\t" + data['epub'])