Rewrite key management & signing

Extend compos_helper to support signing, use it from CompOS.

Expose the public key from the VM. Rename compos_verify_key to
compos_verify and get it to verify the signature against the current
instance's public key.

Also move DICE access to compos_key_main. There's no use having it in
the library - neither the tests nor compos_verify can use it - and it
complicates the build rules.

There's a lot more that can be deleted, but I'll do that in a
follow-up; this is big enough already.

Bug: 218494522
Test: atest CompOsSigningHostTest CompOsDenialHostTest
Change-Id: I2d71f68a595d5ddadb2e7b16937fa6855f5db0ab
diff --git a/compos/verify/native/Android.bp b/compos/verify/native/Android.bp
new file mode 100644
index 0000000..969c9f4
--- /dev/null
+++ b/compos/verify/native/Android.bp
@@ -0,0 +1,51 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+rust_library {
+    name: "libcompos_verify_native_rust",
+    crate_name: "compos_verify_native",
+    srcs: ["lib.rs"],
+    rustlibs: [
+        "libanyhow",
+        "libcxx",
+        "liblibc",
+    ],
+    static_libs: [
+        "libcompos_verify_native_cpp",
+        "libcompos_key",
+    ],
+    shared_libs: [
+        "libcrypto",
+    ],
+    apex_available: ["com.android.compos"],
+}
+
+cc_library_static {
+    name: "libcompos_verify_native_cpp",
+    srcs: ["verify_native.cpp"],
+    static_libs: ["libcompos_key"],
+    shared_libs: [
+        "libbase",
+        "libcrypto",
+    ],
+    generated_headers: ["compos_verify_native_header"],
+    generated_sources: ["compos_verify_native_code"],
+    apex_available: ["com.android.compos"],
+}
+
+genrule {
+    name: "compos_verify_native_code",
+    tools: ["cxxbridge"],
+    cmd: "$(location cxxbridge) $(in) >> $(out)",
+    srcs: ["lib.rs"],
+    out: ["verify_native_cxx_generated.cc"],
+}
+
+genrule {
+    name: "compos_verify_native_header",
+    tools: ["cxxbridge"],
+    cmd: "$(location cxxbridge) $(in) --header >> $(out)",
+    srcs: ["lib.rs"],
+    out: ["lib.rs.h"],
+}