ussl – ssl module

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.


ssl.wrap_socket(sock, keyfile=None, certfile=None, server_side=False, cert_reqs=CERT_NONE, ca_certs=None)

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. sock must be a SOCK_STREAM socket and protocol number socket.IPPROTO_SEC; other socket types are unsupported. Example:

import socket
import ssl
s = socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_SEC)
ss = ssl.wrap_socket(s)
ss.connect(socket.getaddrinfo('', 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.

  • The certificate to validate the other side goes in: ‘/flash/cert/ca.pem’
  • The certificate to authenticate ourselves goes in: ‘/flash/cert/cert.pem’
  • The key for our own certificate goes in: ‘/flash/cert/private.key’


When these files are stored, they are placed inside the internal hidden file system (just like firmware updates), and therefore they are never visible.

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(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_SEC)
ss = ssl.wrap_socket(s, cert_reqs=ssl.CERT_REQUIRED, ca_certs='/flash/cert/ca.pem')
ss.connect(socket.getaddrinfo('', 8441)[0][-1])

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





supported values in cert_reqs