Add commands for generating secret/public keys

src/nix/hash.cc

@@ -132,11 +132,6 @@ struct CmdHash : NixMultiCommand
         command->second->prepare();
         command->second->run();
     }
-
-    void printHelp(const string & programName, std::ostream & out) override
-    {
-        MultiCommand::printHelp(programName, out);
-    }
 };
 
 static auto rCmdHash = registerCommand<CmdHash>("hash");

src/nix/key-convert-secret-to-public.md

@@ -0,0 +1,19 @@
+R""(
+
+# Examples
+
+* Convert a secret key to a public key:
+
+  ```console
+  # echo cache.example.org-0:E7lAO+MsPwTFfPXsdPtW8GKui/5ho4KQHVcAGnX+Tti1V4dUxoVoqLyWJ4YESuZJwQ67GVIksDt47og+tPVUZw== \
+    | nix key convert-secret-to-public
+  cache.example.org-0:tVeHVMaFaKi8lieGBErmScEOuxlSJLA7eO6IPrT1VGc=
+  ```
+
+# Description
+
+This command reads a Ed25519 secret key from standard input, and
+writes the corresponding public key to standard output. For more
+details, see [nix key generate-secret](./nix3-key-generate-secret.md).
+
+)""

src/nix/key-generate-secret.md

@@ -0,0 +1,48 @@
+R""(
+
+# Examples
+
+* Generate a new secret key:
+
+  ```console
+  # nix key generate-secret --key-name cache.example.org-1 > ./secret-key
+  ```
+
+  We can then use this key to sign the closure of the Hello package:
+
+  ```console
+  # nix build nixpkgs#hello
+  # nix store sign-paths --key-file ./secret-key --recursive ./result
+  ```
+
+  Finally, we can verify the store paths using the corresponding
+  public key:
+
+  ```
+  # nix store verify --trusted-public-keys $(nix key convert-secret-to-public < ./secret-key) ./result
+  ```
+
+# Description
+
+This command generates a new Ed25519 secret key for signing store
+paths and prints it on standard output. Use `nix key
+convert-secret-to-public` to get the corresponding public key for
+verifying signed store paths.
+
+The mandatory argument `--key-name` specifies a key name (such as
+`cache.example.org-1). It is used to look up keys on the client when
+it verifies signatures. It can be anything, but it’s suggested to use
+the host name of your cache (e.g.  `cache.example.org`) with a suffix
+denoting the number of the key (to be incremented every time you need
+to revoke a key).
+
+# Format
+
+Both secret and public keys are represented as the key name followed
+by a base-64 encoding of the Ed25519 key data, e.g.
+
+```
+cache.example.org-0:E7lAO+MsPwTFfPXsdPtW8GKui/5ho4KQHVcAGnX+Tti1V4dUxoVoqLyWJ4YESuZJwQ67GVIksDt47og+tPVUZw==
+```
+
+)""

src/nix/sigs.cc

@@ -141,3 +141,90 @@ struct CmdSignPaths : StorePathsCommand
 };
 
 static auto rCmdSignPaths = registerCommand2<CmdSignPaths>({"store", "sign-paths"});
+
+#if HAVE_SODIUM
+struct CmdKeyGenerateSecret : Command
+{
+    std::optional<std::string> keyName;
+
+    CmdKeyGenerateSecret()
+    {
+        addFlag({
+            .longName = "key-name",
+            .description = "identifier of the key (e.g. `cache.example.org-1`)",
+            .labels = {"name"},
+            .handler = {&keyName},
+        });
+    }
+
+    std::string description() override
+    {
+        return "generate a secret key for signing store paths";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "key-generate-secret.md"
+          ;
+    }
+
+    void run() override
+    {
+        if (!keyName)
+            throw UsageError("required argument '--key-name' is missing");
+
+        std::cout << SecretKey::generate(*keyName).to_string();
+    }
+};
+
+struct CmdKeyConvertSecretToPublic : Command
+{
+    std::string description() override
+    {
+        return "generate a public key for verifying store paths from a secret key read from standard input";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "key-convert-secret-to-public.md"
+          ;
+    }
+
+    void run() override
+    {
+        SecretKey secretKey(drainFD(STDIN_FILENO));
+        std::cout << secretKey.toPublicKey().to_string();
+    }
+};
+
+struct CmdKey : NixMultiCommand
+{
+    CmdKey()
+        : MultiCommand({
+                {"generate-secret", []() { return make_ref<CmdKeyGenerateSecret>(); }},
+                {"convert-secret-to-public", []() { return make_ref<CmdKeyConvertSecretToPublic>(); }},
+            })
+    {
+    }
+
+    std::string description() override
+    {
+        return "generate and convert Nix signing keys";
+    }
+
+    Category category() override { return catUtility; }
+
+    void run() override
+    {
+        if (!command)
+            throw UsageError("'nix flake' requires a sub-command.");
+        settings.requireExperimentalFeature("flakes");
+        command->second->prepare();
+        command->second->run();
+    }
+};
+
+static auto rCmdKey = registerCommand<CmdKey>("key");
+#endif

tests/binary-cache.sh

@@ -131,14 +131,14 @@ if [ -n "$HAVE_SODIUM" ]; then
 clearCache
 clearCacheCache
 
-declare -a res=($(nix-store --generate-binary-cache-key test.nixos.org-1 $TEST_ROOT/sk1 $TEST_ROOT/pk1 ))
-publicKey="$(cat $TEST_ROOT/pk1)"
+nix key generate-secret --key-name test.nixos.org-1 > $TEST_ROOT/sk1
+publicKey=$(nix key convert-secret-to-public < $TEST_ROOT/sk1)
 
-res=($(nix-store --generate-binary-cache-key test.nixos.org-1 $TEST_ROOT/sk2 $TEST_ROOT/pk2))
-badKey="$(cat $TEST_ROOT/pk2)"
+nix key generate-secret --key-name test.nixos.org-1 > $TEST_ROOT/sk2
+badKey=$(nix key convert-secret-to-public < $TEST_ROOT/sk2)
 
-res=($(nix-store --generate-binary-cache-key foo.nixos.org-1 $TEST_ROOT/sk3 $TEST_ROOT/pk3))
-otherKey="$(cat $TEST_ROOT/pk3)"
+nix key generate-secret --key-name foo.nixos.org-1 > $TEST_ROOT/sk3
+otherKey=$(nix key convert-secret-to-public < $TEST_ROOT/sk3)
 
 _NIX_FORCE_HTTP= nix copy --to file://$cacheDir?secret-key=$TEST_ROOT/sk1 $outPath