Create a tool for public key encryption

tool.py

@@ -0,0 +1,52 @@
+import os
+import secrets
+import sys
+
+import compact_xchapoly
+import compact_ecdh_curve25519
+
+def keygen():
+	sk = os.urandom(32)
+	pk = compact_ecdh_curve25519.pubkey(sk)
+	return sk, pk
+
+def enc_pk(pk, plaintext):
+	ephemeral_sk, ephemeral_pk = keygen()
+	# Based on monocypher's
+	raw_shared_secret = compact_ecdh_curve25519.ecdh(pk, ephemeral_sk)
+	shared_secret = compact_xchapoly.hchacha20(raw_shared_secret, b'\x00'*24)
+	nonce = os.urandom(24)
+	print(shared_secret, nonce, plaintext)#debg
+	return ephemeral_pk + nonce + compact_xchapoly.enc(b'', shared_secret, nonce, plaintext)
+
+def dec_sk(sk, ciphertext):
+	ephemeral_pk = ciphertext[:32]
+	nonce = ciphertext[32:56]
+	ciphertext = ciphertext[56:]
+	raw_shared_secret = compact_ecdh_curve25519.ecdh(ephemeral_pk, sk)
+	shared_secret = compact_xchapoly.hchacha20(raw_shared_secret, b'\x00'*24)
+	return compact_xchapoly.dec(b'', shared_secret, nonce, ciphertext)
+
+def usage():
+	name=os.path.basename(sys.argv[0])
+	print('Usage: %s -G seckey\n       %s -E pubkey\n       %s -D seckey' % (name, name, name), file=sys.stderr)
+	sys.exit(1)
+
+if __name__ == '__main__':
+	if len(sys.argv) != 3:
+		usage()
+
+	if sys.argv[1] == '-G':
+		sk, pk = keygen()
+		with open(sys.argv[2], 'wb') as f:
+			f.write(sk)
+		print('pubkey:', pk.hex())
+	elif sys.argv[1] == '-E':
+		pk = bytes.fromhex(sys.argv[2])
+		print(enc_pk(pk, input().encode('utf-8')).hex())
+	elif sys.argv[1] == '-D':
+		with open(sys.argv[2], 'rb') as f:
+			sk = f.read()
+		print(dec_sk(sk, bytes.fromhex(input())))
+	else:
+		usage()