[fsbl] add fsbl for cv181x/cv180x

Change-Id: I6809bc5016d4bc148f62be2ed3f8e928ec111f19

fsbl/make_helpers/get_rsa_n.py

@@ -0,0 +1,29 @@
+#!/usr/bin/env python3
+# PYTHON_ARGCOMPLETE_OK
+
+import sys
+import hashlib
+import rsa
+
+
+def main():
+    with open(sys.argv[1], "rb") as ifp:
+        din = ifp.read()
+
+    try:
+        priv = rsa.PrivateKey.load_pkcs1(din)
+    except ValueError:
+        priv = rsa.PrivateKey.load_pkcs1(din, format="DER")
+    x = rsa.common.byte_size(priv.n)
+    n = priv.n.to_bytes(x, byteorder="big")
+    digest = hashlib.sha256(n).digest()
+
+    if sys.argv[2] == "-":
+        sys.stdout.buffer.write(digest)
+    else:
+        with open(sys.argv[2], "wb") as ofp:
+            ofp.write(digest)
+
+
+if __name__ == "__main__":
+    main()