CryptoKit migration (#628)

* WIP.

* WIP

* WIP Edit

* Key selection.

* WIP

* WIP

* Proxy through

* WIP

* Remove verify.

* Migration.

* Comment

* Add param

* Semi-offering key

* Ignore updates if test build.

* Fix rsa public key gen

* Messily fix RSA

* Remove 1024 bit rsa

* Cleanup

* Cleanup

* Clean out MLDSA refs for now

* Dump notifier changes

* Put back UI tweaks

* Fixes.

Sources/Packages/Sources/SecretKit/OpenSSH/LengthAndData.swift

@@ -0,0 +1,23 @@
+import Foundation
+
+extension Data {
+
+    /// Creates an OpenSSH protocol style data object, which has a length header, followed by the data payload.
+    /// - Returns: OpenSSH data.
+    package var lengthAndData: Data {
+        let rawLength = UInt32(count)
+        var endian = rawLength.bigEndian
+        return Data(bytes: &endian, count: UInt32.bitWidth/8) + self
+    }
+
+}
+
+extension String {
+
+    /// Creates an OpenSSH protocol style data object, which has a length header, followed by the data payload.
+    /// - Returns: OpenSSH data.
+    package var lengthAndData: Data {
+        Data(utf8).lengthAndData
+    }
+
+}