diff --git a/Cargo.lock b/Cargo.lock
index 8831acc..f45dabf 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -41,18 +41,41 @@ dependencies = [
  "windows-targets",
 ]
 
+[[package]]
+name = "base64"
+version = "0.22.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
+
+[[package]]
+name = "base64ct"
+version = "1.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "55248b47b0caf0546f7988906588779981c43bb1bc9d0c44087278f80cdb44ba"
+
 [[package]]
 name = "bitflags"
 version = "2.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2261d10cca569e4643e526d8dc2e62e433cc8aba21ab764233731f8d369bf394"
 
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "captra"
 version = "0.1.0"
 dependencies = [
+ "base64",
  "claims",
  "color-eyre",
+ "ed25519-dalek",
  "glob",
  "rand",
  "serde",
@@ -101,6 +124,103 @@ dependencies = [
  "tracing-error",
 ]
 
+[[package]]
+name = "const-oid"
+version = "0.9.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2459377285ad874054d797f3ccebf984978aa39129f6eafde5cdc8315b612f8"
+
+[[package]]
+name = "cpufeatures"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59ed5838eebb26a2bb2e58f6d5b5316989ae9d08bab10e0e6d103e656d1b0280"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "crypto-common"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
+[[package]]
+name = "curve25519-dalek"
+version = "4.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97fb8b7c4503de7d6ae7b42ab72a5a59857b4c937ec27a3d4539dba95b5ab2be"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "curve25519-dalek-derive",
+ "digest",
+ "fiat-crypto",
+ "rustc_version",
+ "subtle",
+ "zeroize",
+]
+
+[[package]]
+name = "curve25519-dalek-derive"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f46882e17999c6cc590af592290432be3bce0428cb0d5f8b6715e4dc7b383eb3"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "der"
+version = "0.7.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7c1832837b905bbfb5101e07cc24c8deddf52f93225eee6ead5f4d63d53ddcb"
+dependencies = [
+ "const-oid",
+ "zeroize",
+]
+
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
+[[package]]
+name = "ed25519"
+version = "2.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "115531babc129696a58c64a4fef0a8bf9e9698629fb97e9e40767d235cfbcd53"
+dependencies = [
+ "pkcs8",
+ "signature",
+]
+
+[[package]]
+name = "ed25519-dalek"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70e796c081cee67dc755e1a36a0a172b897fab85fc3f6bc48307991f64e4eca9"
+dependencies = [
+ "curve25519-dalek",
+ "ed25519",
+ "rand_core",
+ "serde",
+ "sha2",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "errno"
 version = "0.3.14"
@@ -127,6 +247,33 @@ version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
 
+[[package]]
+name = "fiat-crypto"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "28dea519a9695b9977216879a3ebfddf92f1c08c05d984f8996aecd6ecdc811d"
+
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
+[[package]]
+name = "getrandom"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "335ff9f135e4384c8150d6f27c6daed433577f86b4750418338c01a1a2528592"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi 0.11.1+wasi-snapshot-preview1",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.3.3"
@@ -136,7 +283,7 @@ dependencies = [
  "cfg-if",
  "libc",
  "r-efi",
- "wasi",
+ "wasi 0.14.7+wasi-0.2.4",
 ]
 
 [[package]]
@@ -247,6 +394,16 @@ version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3b3cff922bd51709b605d9ead9aa71031d81447142d828eb4a6eba76fe619f9b"
 
+[[package]]
+name = "pkcs8"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f950b2377845cebe5cf8b5165cb3cc1a5e0fa5cfa3e1f7f55707d8fd82e0a7b7"
+dependencies = [
+ "der",
+ "spki",
+]
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.21"
@@ -282,19 +439,20 @@ checksum = "69cdb34c158ceb288df11e18b4bd39de994f6657d83847bdffdbd7f346754b0f"
 
 [[package]]
 name = "rand"
-version = "0.9.2"
+version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6db2770f06117d490610c7488547d543617b21bfa07796d7a12f6f1bd53850d1"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
 dependencies = [
+ "libc",
  "rand_chacha",
  "rand_core",
 ]
 
 [[package]]
 name = "rand_chacha"
-version = "0.9.0"
+version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d3022b5f1df60f26e1ffddd6c66e8aa15de382ae63b3a0c1bfc0e4d3e3f325cb"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
 dependencies = [
  "ppv-lite86",
  "rand_core",
@@ -302,11 +460,11 @@ dependencies = [
 
 [[package]]
 name = "rand_core"
-version = "0.9.3"
+version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "99d9a13982dcf210057a8a78572b2217b667c3beacbf3a0d8b454f6f82837d38"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
 dependencies = [
- "getrandom",
+ "getrandom 0.2.16",
 ]
 
 [[package]]
@@ -332,6 +490,15 @@ version = "0.1.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56f7d92ca342cea22a06f2121d944b4fd82af56988c270852495420f961d4ace"
 
+[[package]]
+name = "rustc_version"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cfcb3a22ef46e85b45de6ee7e79d063319ebb6594faafcf1c225ea92ab6e9b92"
+dependencies = [
+ "semver",
+]
+
 [[package]]
 name = "rustix"
 version = "1.1.2"
@@ -351,6 +518,12 @@ version = "1.0.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "28d3b2b1366ec20994f1fd18c3c594f05c5dd4bc44d8bb0c1c632c8d6829481f"
 
+[[package]]
+name = "semver"
+version = "1.0.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d767eb0aabc880b29956c35734170f26ed551a859dbd361d140cdbeca61ab1e2"
+
 [[package]]
 name = "serde"
 version = "1.0.226"
@@ -394,6 +567,17 @@ dependencies = [
  "serde_core",
 ]
 
+[[package]]
+name = "sha2"
+version = "0.10.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7507d819769d01a365ab707794a4084392c824f54a7a6a7862f8c3d0892b283"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "sharded-slab"
 version = "0.1.7"
@@ -403,12 +587,37 @@ dependencies = [
  "lazy_static",
 ]
 
+[[package]]
+name = "signature"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77549399552de45a898a580c1b41d445bf730df867cc44e6c0233bbc4b8329de"
+dependencies = [
+ "rand_core",
+]
+
 [[package]]
 name = "smallvec"
 version = "1.15.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "67b1b7a3b5fe4f1376887184045fcf45c69e92af734b7aaddc05fb777b6fbd03"
 
+[[package]]
+name = "spki"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d91ed6c858b01f942cd56b37a94b3e0a1798290327d1236e4d9cf4eaca44d29d"
+dependencies = [
+ "base64ct",
+ "der",
+]
+
+[[package]]
+name = "subtle"
+version = "2.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"
+
 [[package]]
 name = "syn"
 version = "2.0.106"
@@ -427,7 +636,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2d31c77bdf42a745371d260a26ca7163f1e0924b64afa0b688e61b5a9fa02f16"
 dependencies = [
  "fastrand",
- "getrandom",
+ "getrandom 0.3.3",
  "once_cell",
  "rustix",
  "windows-sys",
@@ -526,6 +735,12 @@ dependencies = [
  "tracing-serde",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.18.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1dccffe3ce07af9386bfd29e80c0ab1a8205a2fc34e4bcd40364df902cfa8f3f"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.19"
@@ -538,6 +753,18 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ba73ea9cf16a25df0c8caa16c51acb937d5712a8429db78a3ee29d5dcacd3a65"
 
+[[package]]
+name = "version_check"
+version = "0.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
+
+[[package]]
+name = "wasi"
+version = "0.11.1+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ccf3ec651a847eb01de73ccad15eb7d99f80485de043efb2f370cd654f4ea44b"
+
 [[package]]
 name = "wasi"
 version = "0.14.7+wasi-0.2.4"
@@ -654,3 +881,9 @@ dependencies = [
  "quote",
  "syn",
 ]
+
+[[package]]
+name = "zeroize"
+version = "1.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ced3678a2879b30306d323f4542626697a464a97c0a07c9aebf7ebca65cd4dde"
diff --git a/Cargo.toml b/Cargo.toml
index 033ffa8..b8abf5e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,9 +10,11 @@ keywords = ["wasm", "sandbox", "capabilities", "plugins", "traces"]
 categories = ["cryptography::randomness", "encoding"]
 
 [dependencies]
+base64 = "0.22"
 color-eyre = "0.6"
+ed25519-dalek = { version = "2.2", features = ["rand_core"] }
 glob = "0.3"
-rand = "0.9"
+rand = "0.8"                                                                # ed25519-dalek depends on rand_core v0.6
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 tracing = "0.1"
diff --git a/src/lib.rs b/src/lib.rs
index 13a723b..7501cfb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,5 @@
 use color_eyre::eyre::Result;
+use ed25519_dalek::{PUBLIC_KEY_LENGTH, SigningKey};
 use glob::Pattern;
 use rand::{Rng, SeedableRng, rngs::StdRng};
 use serde::{Deserialize, Serialize};
@@ -46,21 +47,34 @@ pub struct TraceEvent {
     pub ts_seed: u64,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SignedTrace {
+    pub run_id: String,
+    pub manifest_hash: String,
+    pub trace_json: String,
+    pub signature: String,
+}
+
 #[derive(Debug)]
 pub struct HostState {
     pub manifest: CapabilityManifest,
     pub trace: Vec<TraceEvent>,
     pub seed: u64,
+    pub keypair: SigningKey,
+    pub pubkey: [u8; PUBLIC_KEY_LENGTH],
 }
 
 impl HostState {
     #[inline]
     #[must_use]
-    pub const fn new(manifest: CapabilityManifest, seed: u64) -> Self {
+    pub fn new(manifest: CapabilityManifest, seed: u64, keypair: SigningKey) -> Self {
+        let pubkey = keypair.verifying_key().to_bytes();
         Self {
             manifest,
             trace: Vec::new(),
             seed,
+            keypair,
+            pubkey,
         }
     }
 
@@ -80,7 +94,7 @@ impl HostState {
         let path_str = path.as_ref().to_string_lossy();
 
         let mut rng = StdRng::seed_from_u64(self.seed.wrapping_mul(PRIME_MULTIPLIER + seq));
-        let ts_seed = rng.random();
+        let ts_seed = rng.r#gen();
 
         let is_allowed = read_patterns.iter().any(|pattern| {
             Pattern::new(pattern)
@@ -154,6 +168,7 @@ pub fn init_tracing() {
 mod tests {
     use super::*;
     use claims::{assert_ok, assert_some};
+    use rand::rngs::OsRng;
     use tempfile::tempdir;
 
     #[test]
@@ -182,7 +197,9 @@ mod tests {
 
         let manifest = assert_ok!(load_manifest("examples/manifest.json"), "Load failed");
         let fixed_seed = 12345;
-        let mut host = HostState::new(manifest, fixed_seed);
+        let mut csprng = OsRng;
+        let keypair = SigningKey::generate(&mut csprng);
+        let mut host = HostState::new(manifest, fixed_seed, keypair);
 
         // allowed - expect a tracing event
         let out1 = host.execute_plugin("./workspace/config.toml");
@@ -230,12 +247,16 @@ mod tests {
         let manifest = assert_ok!(load_manifest("examples/manifest.json"), "Load failed");
 
         let fixed_seed = 12345;
+        let mut csprng1 = OsRng;
+        let keypair1 = SigningKey::generate(&mut csprng1);
 
-        let mut host1 = HostState::new(manifest.clone(), fixed_seed);
+        let mut host1 = HostState::new(manifest.clone(), fixed_seed, keypair1);
         assert!(!host1.execute_plugin("./allowed.txt"));
         let trace1 = host1.finalize_trace();
 
-        let mut host2 = HostState::new(manifest, fixed_seed);
+        let mut csprng2 = OsRng;
+        let keypair2 = SigningKey::generate(&mut csprng2);
+        let mut host2 = HostState::new(manifest, fixed_seed, keypair2);
         assert!(!host2.execute_plugin("./allowed.txt"));
         let trace2 = host2.finalize_trace();