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Firmware & API Reference
MicroPython Modules
ussl

ussl

This module provides access to Transport Layer Security (often known as “Secure Sockets Layer”) encryption and peer authentication facilities for network sockets, both client-side and server-side.

Methods

ssl.wrap_socket(sock, [keyfile=None, certfile=None, server_side=False, cert_reqs=CERT_NONE, ssl_version=0, ca_certs=None, server_hostname=None, saved_session=None, timeout=10sec])

Takes an instance sock of socket.socket, and returns an instance of ssl.SSLSocket, a subtype of socket.socket, which wraps the underlying socket in an SSL context. Example:

import socket
import ssl
s = socket.socket()
ss = ssl.wrap_socket(s)
ss.connect(socket.getaddrinfo('www.google.com', 443)[0][-1])

Certificates must be used in order to validate the other side of the connection, and also to authenticate ourselves with the other end. Such certificates must be stored as files using the FTP server, and they must be placed in specific paths with specific names.

For instance, to connect to the Blynk servers using certificates, take the file ca.pem located in the blynk examples folder and put it in /flash/cert/. Then do:

import socket
import ssl
s = socket.socket()
ss = ssl.wrap_socket(s, cert_reqs=ssl.CERT_REQUIRED, ca_certs='/flash/cert/ca.pem')
ss.connect(socket.getaddrinfo('cloud.blynk.cc', 8441)[0][-1])

SSL sockets inherit all methods and from the standard sockets, see the usocket module.

timeout : specify a Timeout in Seconds for the SSL handshake operation between client and server, default is 10 seconds

ssl.save_session(ssl_sock)

Takes an instance ssl_sock of ssl.SSLSocket, and returns an instance of ssl.SSLSession. Saved session can be resumed later, thereby reducing mobile data and time required. Example:

import socket
import ssl
s = socket.socket()
ss = ssl.wrap_socket(s)
ss.connect(socket.getaddrinfo('www.google.com', 443)[0][-1])
ses = ssl.save_session(ss)
ss.close()
ss = ssl.wrap_socket(s, saved_session=ses)
ss.connect(socket.getaddrinfo('www.google.com', 443)[0][-1])

Exceptions

  • ssl.SSLError

Constants

  • ssl.CERT_NONE, ssl.CERT_OPTIONAL, ssl.CERT_REQUIRED: Supported values in cert_reqs