Upgrade signing key generation (#379)

* adds the upgrade signing key generation and the partition offset

* use openssl in build.rs instead

src/embedded_flash/buffer_upgrade.rs

@@ -57,6 +57,10 @@ impl UpgradeStorage for BufferUpgradeStorage {
         }
     }
 
+    fn partition_address(&self) -> usize {
+        0x60000
+    }
+
     fn partition_length(&self) -> usize {
         PARTITION_LENGTH
     }

src/embedded_flash/syscall.rs

@@ -317,6 +317,10 @@ impl UpgradeStorage for SyscallUpgradeStorage {
         }
     }
 
+    fn partition_address(&self) -> usize {
+        self.partition.start()
+    }
+
     fn partition_length(&self) -> usize {
         self.partition.length()
     }

src/embedded_flash/upgrade_storage.rs

@@ -34,6 +34,9 @@ pub trait UpgradeStorage {
     /// Returns [`StorageError::OutOfBounds`] if the data does not fit the partition.
     fn write_partition(&mut self, offset: usize, data: &[u8]) -> StorageResult<()>;
 
+    /// Returns the address of the partition.
+    fn partition_address(&self) -> usize;
+
     /// Returns the length of the partition.
     fn partition_length(&self) -> usize;