Initial proof-of-concept SM-DP+ for GSMA consumer eSIM RSP

This commit introduces

* the osmo-smdpp.py program implementing the main procedures and the
  HTTP/REST based ES9+
* python modules for ES8+ and non-volatile RSP Session State storage
* the ASN.1 source files required to parse/encode RSP
* 3GPP test certificates from SGP.26
* an unsigned profile package (UPP) of a SAIP v2.3 TS48 test profile

As I couldn't get the 'Klein' tls support to work, the SM-DP+ code
currently does not support HTTPS/TLS but plan HTTP, so you either have
to modify your LPA to use HTTP instead of HTTPS, or put a TLS proxy in
front.

I have successfully installed an eSIM profile on a test eUICC that
contains certificate/key data within the test CI defined in GSMA SGP.26

Change-Id: I6232847432dc6920cd2bd08c84d7099c29ca1c11

docs/osmo-smdpp.rst

@@ -0,0 +1,93 @@
+osmo-smdpp
+==========
+
+`osmo-smdpp` is a proof-of-concept implementation of a minimal **SM-DP+** as specified for the *GSMA
+Consumer eSIM Remote SIM provisioning*.
+
+At least at this point, it is intended to be used for research and development, and not as a
+production SM-DP+.
+
+Unless you are a GSMA SAS-SM accredited SM-DP+ operator and have related DPtls, DPauth and DPpb
+certificates signed by the GSMA CI, you **can not use osmo-smdpp with regular production eUICC**.
+This is due to how the GSMA eSIM security architecture works.  You can, however, use osmo-smdpp with
+so-called *test-eUICC*, which contain certificates/keys signed by GSMA test certificates as laid out
+in GSMA SGP.26.
+
+At this point, osmo-smdpp does not support anything beyond the bare minimum required to download
+eSIM profiles to an eUICC.  Specifically, there is no ES2+ interface, and there is no built-in
+support for profile personalization yet.
+
+osmo-smdpp currently
+
+* always provides the exact same profile to every request.  The profile always has the same IMSI and
+  ICCID.
+* **is absolutely insecure**, as it
+
+ * does not perform any certificate verification
+ * does not evaluate/consider any *Matching ID* or *Confirmation Code*
+ * stores the sessions in an unencrypted _python shelve_ and is hence leaking one-time key materials
+   used for profile encryption and signing.
+
+
+Running osmo-smdpp
+------------------
+
+osmo-smdpp does not have built-in TLS support as the used *twisted* framework appears to have
+problems when using the example elliptic curve certificates (both NIST and Brainpool) from GSMA.
+
+So in order to use it, you have to put it behind a TLS reverse proxy, which terminates the ES9+
+HTTPS from the LPA, and then forwards it as plain HTTP to osmo-smdpp.
+
+nginx as TLS proxy
+~~~~~~~~~~~~~~~~~~
+
+If you use `nginx` as web server, you can use the following configuration snippet::
+
+  upstream smdpp {
+          server localhost:8000;
+  }
+
+  server {
+          listen 443 ssl;
+          server_name testsmdpplus1.example.com;
+
+          ssl_certificate /my/path/to/pysim/smdpp-data/certs/DPtls/CERT_S_SM_DP_TLS_NIST.pem;
+          ssl_certificate_key /my/path/to/pysim/smdpp-data/certs/DPtls/SK_S_SM_DP_TLS_NIST.pem;
+
+          location / {
+                  proxy_read_timeout 600s;
+
+                  proxy_hide_header X-Powered-By;
+                  proxy_set_header X-Real-IP $remote_addr;
+                  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+                  proxy_set_header X-Forwarded-Proto https;
+                  proxy_set_header X-Forwarded-Port $proxy_port;
+                  proxy_set_header Host $host;
+
+                  proxy_pass http://smdpp/;
+          }
+  }
+
+You can of course achieve a similar functionality with apache, lighttpd or many other web server
+software.
+
+
+osmo-smdpp
+~~~~~~~~~~
+
+osmo-smdpp currently doesn't have any configuration file or command line options.  You just run it,
+and it will bind its plain-HTTP ES9+ interface to local TCP port 8000.
+
+The `smdpp-data/certs`` directory contains the DPtls, DPauth and DPpb as well as CI certificates
+used; they are copied from GSMA SGP.26 v2.
+
+The `smdpp-data/upp` directory contains the UPP (Unprotected Profile Package) used.
+
+
+DNS setup for your LPA
+~~~~~~~~~~~~~~~~~~~~~~
+
+The LPA must resolve `testsmdpplus1.example.com` to the IP address of your TLS proxy.
+
+It must also accept the TLS certificates used by your TLS proxy.
+