1 files changed, 149 insertions, 0 deletions
diff --git a/circuitpython/lib/nrfutil/nordicsemi/dfu/signing.py b/circuitpython/lib/nrfutil/nordicsemi/dfu/signing.py
new file mode 100644
index 0000000..ca98eb1
--- /dev/null
+++ b/circuitpython/lib/nrfutil/nordicsemi/dfu/signing.py
@@ -0,0 +1,149 @@
+# Copyright (c) 2015 Nordic Semiconductor. All Rights Reserved.
+#
+# The information contained herein is property of Nordic Semiconductor ASA.
+# Terms and conditions of usage are described in detail in NORDIC
+# SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
+#
+# Licensees are granted free, non-transferable use of the information. NO
+# WARRANTY of ANY KIND is provided. This heading must NOT be removed from
+# the file.
+
+import hashlib
+import binascii
+
+try:
+    from ecdsa import SigningKey
+    from ecdsa.curves import NIST256p
+    from ecdsa.keys import sigencode_string
+except Exception:
+    print "Failed to import ecdsa, cannot do signing"
+
+from nordicsemi.exceptions import InvalidArgumentException, IllegalStateException
+
+
+class Signing(object):
+    """
+    Class for singing of hex-files
+    """
+    def gen_key(self, filename):
+        """
+        Generate a new Signing key using NIST P-256 curve
+        """
+        self.sk = SigningKey.generate(curve=NIST256p)
+
+        with open(filename, "w") as sk_file:
+            sk_file.write(self.sk.to_pem())
+
+    def load_key(self, filename):
+        """
+        Load signing key (from pem file)
+        """
+        with open(filename, "r") as sk_file:
+            sk_pem = sk_file.read()
+
+        self.sk = SigningKey.from_pem(sk_pem)
+
+        sk_hex = "".join(c.encode('hex') for c in self.sk.to_string())
+
+    def sign(self, init_packet_data):
+        """
+        Create signature for init package using P-256 curve and SHA-256 as hashing algorithm
+        Returns R and S keys combined in a 64 byte array
+        """
+        # Add assertion of init_packet
+        if self.sk is None:
+            raise IllegalStateException("Can't save key. No key created/loaded")
+
+        # Sign the init-packet
+        signature = self.sk.sign(init_packet_data, hashfunc=hashlib.sha256, sigencode=sigencode_string)
+        return signature
+
+    def verify(self, init_packet, signature):
+        """
+        Verify init packet
+        """
+        # Add assertion of init_packet
+        if self.sk is None:
+            raise IllegalStateException("Can't save key. No key created/loaded")
+
+        vk = self.sk.get_verifying_key()
+
+        # Verify init packet
+        try:
+            vk.verify(signature, init_packet, hashfunc=hashlib.sha256)
+        except:
+            return False
+
+        return True
+
+    def get_vk(self, output_type):
+        """
+        Get verification key (as hex, code or pem)
+        """
+        if self.sk is None:
+            raise IllegalStateException("Can't get key. No key created/loaded")
+
+        if output_type is None:
+            raise InvalidArgumentException("Invalid output type for signature.")
+        elif output_type == 'hex':
+            return self.get_vk_hex()
+        elif output_type == 'code':
+            return self.get_vk_code()
+        elif output_type == 'pem':
+            return self.get_vk_pem()
+        else:
+            raise InvalidArgumentException("Invalid argument. Can't get key")
+
+    def get_vk_hex(self):
+        """
+        Get the verification key as hex
+        """
+        if self.sk is None:
+            raise IllegalStateException("Can't get key. No key created/loaded")
+
+        vk = self.sk.get_verifying_key()
+        vk_hexlify = binascii.hexlify(vk.to_string())
+
+        vk_hex = "Verification key Qx: {0}\n".format(vk_hexlify[0:64])
+        vk_hex += "Verification key Qy: {0}".format(vk_hexlify[64:128])
+
+        return vk_hex
+
+    def get_vk_code(self):
+        """
+        Get the verification key as code
+        """
+        if self.sk is None:
+            raise IllegalStateException("Can't get key. No key created/loaded")
+
+        vk = self.sk.get_verifying_key()
+        vk_hex = binascii.hexlify(vk.to_string())
+
+        vk_x_separated = ""
+        vk_x_str = vk_hex[0:64]
+        for i in xrange(0, len(vk_x_str), 2):
+            vk_x_separated += "0x" + vk_x_str[i:i+2] + ", "
+        vk_x_separated = vk_x_separated[:-2]
+
+        vk_y_separated = ""
+        vk_y_str = vk_hex[64:128]
+        for i in xrange(0, len(vk_y_str), 2):
+            vk_y_separated += "0x" + vk_y_str[i:i+2] + ", "
+        vk_y_separated = vk_y_separated[:-2]
+
+        vk_code = "static uint8_t Qx[] = {{ {0} }};\n".format(vk_x_separated)
+        vk_code += "static uint8_t Qy[] = {{ {0} }};".format(vk_y_separated)
+
+        return vk_code
+
+    def get_vk_pem(self):
+        """
+        Get the verification key as PEM
+        """
+        if self.sk is None:
+            raise IllegalStateException("Can't get key. No key created/loaded")
+
+        vk = self.sk.get_verifying_key()
+        vk_pem = vk.to_pem()
+
+        return vk_pem