add nix flake

* obvious password promt

* prompt interaction with FIDO device

.gitignore

@@ -6,3 +6,5 @@ fido2luks.bash
 fido2luks.elv
 fido2luks.fish
 fido2luks.zsh
+result
+result-*

flake.lock

@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "naersk": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1612192764,
+        "narHash": "sha256-7EnLtZQWP6511G1ZPA7FmJlqAr3hWsAYb24tvTvJ/ec=",
+        "owner": "nmattia",
+        "repo": "naersk",
+        "rev": "6e149bfd726a8ebefa415f2d713ba6d942435abd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nmattia",
+        "repo": "naersk",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1611910458,
+        "narHash": "sha256-//j54S14v9lp3YKizS1WZW3WKwLjGTzvwhHfUAaRBPQ=",
+        "path": "/nix/store/z5g10k571cc5q9yvr0bafzswp0ggawjw-source",
+        "rev": "6e7f25001fe6874f7ae271891f709bbf50a22c45",
+        "type": "path"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "naersk": "naersk",
+        "nixpkgs": "nixpkgs",
+        "utils": "utils"
+      }
+    },
+    "utils": {
+      "locked": {
+        "lastModified": 1610051610,
+        "narHash": "sha256-U9rPz/usA1/Aohhk7Cmc2gBrEEKRzcW4nwPWMPwja4Y=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "3982c9903e93927c2164caa727cd3f6a0e6d14cc",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,61 @@
+{
+  description = "Decrypt your LUKS partition using a FIDO2 compatible authenticator";
+
+  inputs = {
+    utils.url = "github:numtide/flake-utils";
+    naersk = {
+      url = "github:nmattia/naersk";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+  };
+
+  outputs = { self, nixpkgs, utils, naersk }:
+    let
+      root = ./.;
+      pname = (builtins.fromTOML (builtins.readFile ./Cargo.toml)).package.name;
+      forPkgs = pkgs:
+        let
+          naersk-lib = naersk.lib."${pkgs.system}";
+          buildInputs = with pkgs; [ cryptsetup ];
+          LIBCLANG_PATH = "${pkgs.clang.cc.lib}/lib";
+          nativeBuildInputs = with pkgs; [
+            pkgconfig
+            clang
+          ];
+        in
+        rec {
+          # `nix build`
+          packages.${pname} = naersk-lib.buildPackage {
+            inherit pname root buildInputs nativeBuildInputs LIBCLANG_PATH;
+          };
+          defaultPackage = packages.${pname};
+
+          # `nix run`
+          apps.${pname} = utils.lib.mkApp {
+            drv = packages.${pname};
+          };
+          defaultApp = apps.${pname};
+
+          # `nix flake check`
+          checks = {
+            fmt = with pkgs; runCommandLocal "${pname}-fmt" { buildInputs = [ cargo rustfmt nixpkgs-fmt ]; } ''
+              cd ${root}
+              cargo fmt -- --check
+              nixpkgs-fmt --check *.nix
+              touch $out
+            '';
+          };
+
+          # `nix develop`
+          devShell = pkgs.mkShell {
+            nativeBuildInputs = with pkgs; [ rustc cargo rustfmt nixpkgs-fmt ] ++ nativeBuildInputs;
+            inherit buildInputs LIBCLANG_PATH;
+          };
+        };
+      forSystem = system: forPkgs nixpkgs.legacyPackages."${system}";
+    in
+    (utils.lib.eachSystem [ "aarch64-linux" "i686-linux" "x86_64-linux" ] forSystem) // {
+      overlay = final: prev: (forPkgs final).packages;
+    };
+
+}

src/cli.rs

@@ -71,6 +71,12 @@ pub fn parse_cmdline() -> Args {
     Args::from_args()
 }
 
+pub fn prompt_interaction(interactive: bool) {
+    if interactive {
+        println!("Authorize using your FIDO device");
+    }
+}
+
 pub fn run_cli() -> Fido2LuksResult<()> {
     let mut stdout = io::stdout();
     let args = parse_cmdline();
@@ -109,6 +115,7 @@ pub fn run_cli() -> Fido2LuksResult<()> {
             } else {
                 secret.salt.obtain_sha256(&secret.password_helper)
             }?;
+            prompt_interaction(interactive);
             let (secret, _cred) = derive_secret(
                 credentials.ids.0.as_slice(),
                 &salt,
@@ -164,13 +171,16 @@ pub fn run_cli() -> Fido2LuksResult<()> {
                     } => Ok((util::read_keyfile(file)?, None)),
                     OtherSecret {
                         fido_device: true, ..
-                    } => Ok(derive_secret(
-                        &credentials.ids.0,
-                        &salt(salt_q, verify)?,
-                        authenticator.await_time,
-                        pin.as_deref(),
-                    )
-                    .map(|(secret, cred)| (secret[..].to_vec(), Some(cred)))?),
+                    } => {
+                        prompt_interaction(interactive);
+                        Ok(derive_secret(
+                            &credentials.ids.0,
+                            &salt(salt_q, verify)?,
+                            authenticator.await_time,
+                            pin.as_deref(),
+                        )
+                        .map(|(secret, cred)| (secret[..].to_vec(), Some(cred)))?)
+                    }
                     _ => Ok((
                         util::read_password(salt_q, verify)?.as_bytes().to_vec(),
                         None,
@@ -178,6 +188,7 @@ pub fn run_cli() -> Fido2LuksResult<()> {
                 }
             };
             let secret = |q: &str, verify: bool| -> Fido2LuksResult<([u8; 32], FidoCredential)> {
+                prompt_interaction(interactive);
                 derive_secret(
                     &credentials.ids.0,
                     &salt(q, verify)?,
@@ -274,6 +285,7 @@ pub fn run_cli() -> Fido2LuksResult<()> {
 
             // Cow shouldn't be necessary
             let secret = |credentials: Cow<'_, Vec<HexEncoded>>| {
+                prompt_interaction(interactive);
                 derive_secret(
                     credentials.as_ref(),
                     &salt("Password", false)?,