@@ -1,7 +1,60 @@
 {
   "nodes": {
+    "esp32-overlay": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      },
+      "locked": {
+        "lastModified": 1767146219,
+        "narHash": "sha256-dviXadLLdKhoW9apdBoF+UpGxgcukSin6h6oaxKY/w4=",
+        "owner": "mirrexagon",
+        "repo": "nixpkgs-esp-dev",
+        "rev": "a202c3c73bed7e2cb8c6870f80781993dab41fcd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "mirrexagon",
+        "repo": "nixpkgs-esp-dev",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
+        "lastModified": 1758070117,
+        "narHash": "sha256-uLwwHFCZnT1c3N3biVe/0hCkag2GSrf9+M56+Okf+WY=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "e9b7f2ff62b35f711568b1f0866243c7c302028d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-25.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
+      "locked": {
         "lastModified": 1767047869,
         "narHash": "sha256-tzYsEzXEVa7op1LTnrLSiPGrcCY6948iD0EcNLWcmzo=",
         "owner": "nixos",
@@ -18,7 +71,23 @@ }
     },
     "root": {
       "inputs": {
-        "nixpkgs": "nixpkgs"
+        "esp32-overlay": "esp32-overlay",
+        "nixpkgs": "nixpkgs_2"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
       }
     }
   },

@@ -3,17 +3,24 @@ description = "TinyCrypT Build Environment";
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-25.11";
+    esp32-overlay.url = "github:mirrexagon/nixpkgs-esp-dev";
   };
 
   outputs =
     {
       self,
       nixpkgs,
+      esp32-overlay,
       ...
     }@inputs:
     let
       system = "x86_64-linux";
       pkgs = nixpkgs.legacyPackages.${system};
+      pkgs-persephone = import nixpkgs {
+        overlays = [ esp32-overlay.overlays.default ];
+        inherit system;
+        config.permittedInsecurePackages = [ "python3.13-ecdsa-0.19.1" ];
+      };
       aphrodite_shl = pkgs.mkShell {
         name = "tct-tooling-env-aphrodite";
         packages = with pkgs; [
@@ -50,12 +57,25 @@ bear
           tokei
         ];
       };
+      persephone_shl = pkgs.mkShell {
+        name = "tct-tooling-env-persephone";
+        packages = with pkgs-persephone; [
+          ninja
+          meson
+          esp-idf-xtensa
+          clang-tools
+          valgrind
+          bear
+          tokei
+        ];
+      };
     in
     {
       devShells.${system} = {
         default = aphrodite_shl;
         teiresia = teiresia_shl;
         demeter = demeter_shl;
+        persephone = persephone_shl;
       };
     };
 }

@@ -0,0 +1,12 @@
+[binaries]
+c = 'xtensa-esp-elf-gcc'
+cpp = 'xtensa-esp-elf-g++'
+ar = 'xtensa-esp-elf-ar'
+windres = 'xtensa-esp-elf-windres'
+strip = 'xtensa-esp-elf-strip'
+
+[host_machine]
+system = 'linux'
+cpu_family = 'xtensa'
+cpu = 'lx7'
+endian = 'little'

@@ -697,7 +697,7 @@ }
 
 #ifndef TCT_LOWMEM
 
-#include "tinycrypt/ed25519_precompute.h"
+#include "tinycrypt/portable/ed25519_precompute.h"
 
 static void
 xB (const uint32_t *k, uint32_t *x, uint32_t *y, uint32_t *z, uint32_t *t)