Export/import "raw" keys for external storage.

Exported keys are wrapped with the MKM KEK, not a transit KEK, and can
only be imported back to the same HSM.

The idea is to support operators who have more keys than will fit on the
HSM, so they will cycle keys into and out of the HSM as needed.

NOTE that hashsig is, as always, special. The hashsig key has an internal
index that is updated on every signature. To prevent a hashsig key from
being re-imported with an old index (which would compromise the security
of the key), the hashsig key is disabled on export, and must be deleted
from the HSM before being re-imported.

1 files changed, 20 insertions, 0 deletions

diff --git a/cryptech/libhal.py b/cryptech/libhal.py
index 647dbd6..1899102 100644
--- a/cryptech/libhal.py
+++ b/cryptech/libhal.py
@@ -191,6 +191,8 @@ RPCFunc.define('''
     RPC_FUNC_PKEY_EXPORT,
     RPC_FUNC_PKEY_IMPORT,
     RPC_FUNC_PKEY_GENERATE_HASHSIG,
+    RPC_FUNC_PKEY_EXPORT_RAW,
+    RPC_FUNC_PKEY_IMPORT_RAW,
 ''')
 
 class HALDigestAlgorithm(Enum): pass
@@ -434,6 +436,12 @@ class PKey(Handle):
     def import_pkey(self, pkcs8, kek, flags = 0):
         return self.hsm.pkey_import(kekek = self, pkcs8 = pkcs8, kek = kek, flags = flags)
 
+    def export_raw_pkey(self, pkey):
+        return self.hsm.pkey_export_raw(pkey = pkey, der_max = 5480)
+
+    def import_raw_pkey(self, der, flags = 0):
+        return self.hsm.pkey_import_raw(der = der, flags = flags)
+
 class ContextManagedUnpacker(xdrlib.Unpacker):
 
     def __enter__(self):
@@ -710,3 +718,15 @@ class HSM(object):
             pkey = PKey(self, r.unpack_uint(), UUID(bytes = r.unpack_bytes()))
             logger.debug("Imported pkey %s", pkey.uuid)
             return pkey
+
+    def pkey_export_raw(self, pkey, der_max = 2560):
+        with self.rpc(RPC_FUNC_PKEY_EXPORT_RAW, pkey, der_max) as r:
+            der = r.unpack_bytes(), r.unpack_bytes()
+            logger.debug("Exported raw pkey %s", pkey.uuid)
+            return der
+
+    def pkey_import_raw(self, der, flags = 0, client = 0, session = 0):
+        with self.rpc(RPC_FUNC_PKEY_IMPORT_RAW, session, der, flags, client = client) as r:
+            pkey = PKey(self, r.unpack_uint(), UUID(bytes = r.unpack_bytes()))
+            logger.debug("Imported raw pkey %s", pkey.uuid)
+            return pkey