fix(license): harden release key validation and fingerprint logging

(cherry picked from commit f253ed2778)

internal/license/pubkey.go

@@ -2,6 +2,7 @@ package license
 
 import (
 	"crypto/ed25519"
+	"crypto/sha256"
 	"encoding/base64"
 	"os"
 	"strings"
@@ -14,6 +15,14 @@ import (
 // Example: go build -ldflags "-X github.com/rcourtman/pulse-go-rewrite/internal/license.EmbeddedPublicKey=BASE64_KEY"
 var EmbeddedPublicKey string = ""
 
+func publicKeyFingerprint(key ed25519.PublicKey) string {
+	if len(key) == 0 {
+		return ""
+	}
+	sum := sha256.Sum256(key)
+	return "SHA256:" + base64.StdEncoding.EncodeToString(sum[:])
+}
+
 // InitPublicKey initializes the public key for license validation.
 // Priority:
 //  1. PULSE_LICENSE_PUBLIC_KEY environment variable (base64 encoded)
@@ -30,7 +39,10 @@ func InitPublicKey() {
 			// Fall through to try embedded key instead of returning
 		} else {
 			SetPublicKey(key)
-			log.Info().Msg("License public key loaded from environment")
+			log.Info().
+				Str("source", "environment").
+				Str("fingerprint", publicKeyFingerprint(key)).
+				Msg("License public key loaded")
 			return
 		}
 	}
@@ -42,7 +54,10 @@ func InitPublicKey() {
 			log.Error().Err(err).Msg("Failed to decode embedded public key")
 		} else {
 			SetPublicKey(key)
-			log.Info().Msg("License public key loaded from embedded key")
+			log.Info().
+				Str("source", "embedded").
+				Str("fingerprint", publicKeyFingerprint(key)).
+				Msg("License public key loaded")
 			return
 		}
 	}

internal/license/pubkey_test.go

@@ -2,8 +2,10 @@ package license
 
 import (
 	"crypto/ed25519"
+	"crypto/sha256"
 	"encoding/base64"
 	"os"
+	"strings"
 	"testing"
 )
 
@@ -115,3 +117,22 @@ func TestDecodePublicKey(t *testing.T) {
 		})
 	}
 }
+
+func TestPublicKeyFingerprint(t *testing.T) {
+	pub, _, _ := ed25519.GenerateKey(nil)
+
+	got := publicKeyFingerprint(pub)
+	if !strings.HasPrefix(got, "SHA256:") {
+		t.Fatalf("expected SHA256 prefix, got %q", got)
+	}
+
+	sum := sha256.Sum256(pub)
+	want := "SHA256:" + base64.StdEncoding.EncodeToString(sum[:])
+	if got != want {
+		t.Fatalf("fingerprint mismatch: got %q want %q", got, want)
+	}
+
+	if empty := publicKeyFingerprint(nil); empty != "" {
+		t.Fatalf("expected empty fingerprint for nil key, got %q", empty)
+	}
+}

scripts/build-release.sh

@@ -19,12 +19,41 @@ RELEASE_DIR="release"
 
 echo "Building Pulse v${VERSION}..."
 
-# Optional public key embedding for license validation
+# Require public key embedding for release-grade license validation.
+# Explicitly opt out with PULSE_ALLOW_MISSING_LICENSE_KEY=true (not recommended).
 LICENSE_LDFLAGS=""
-if [[ -n "${PULSE_LICENSE_PUBLIC_KEY:-}" ]]; then
-    LICENSE_LDFLAGS="-X github.com/rcourtman/pulse-go-rewrite/internal/license.EmbeddedPublicKey=${PULSE_LICENSE_PUBLIC_KEY}"
+if [[ -z "${PULSE_LICENSE_PUBLIC_KEY:-}" ]]; then
+    if [[ "${PULSE_ALLOW_MISSING_LICENSE_KEY:-false}" == "true" ]]; then
+        echo "Warning: PULSE_LICENSE_PUBLIC_KEY not set; continuing because PULSE_ALLOW_MISSING_LICENSE_KEY=true."
+    else
+        echo "Error: PULSE_LICENSE_PUBLIC_KEY is required for release builds." >&2
+        echo "Set PULSE_ALLOW_MISSING_LICENSE_KEY=true only for local non-release debugging." >&2
+        exit 1
+    fi
 else
-    echo "Warning: PULSE_LICENSE_PUBLIC_KEY not set; Pulse Pro license activation will fail for release binaries."
+    decoded_key_len=$(printf '%s' "${PULSE_LICENSE_PUBLIC_KEY}" | openssl base64 -d -A 2>/dev/null | wc -c | tr -d ' ')
+    if [[ "${decoded_key_len}" != "32" ]]; then
+        echo "Error: PULSE_LICENSE_PUBLIC_KEY must decode to 32 bytes (Ed25519 public key)." >&2
+        exit 1
+    fi
+
+    if [[ -n "${PULSE_LICENSE_PUBLIC_KEY_FINGERPRINT:-}" ]]; then
+        expected_fingerprint="${PULSE_LICENSE_PUBLIC_KEY_FINGERPRINT#SHA256:}"
+        actual_fingerprint=$(printf '%s' "${PULSE_LICENSE_PUBLIC_KEY}" | openssl base64 -d -A 2>/dev/null | openssl dgst -sha256 -binary | openssl base64 -A)
+        if [[ -z "${actual_fingerprint}" ]]; then
+            echo "Error: Failed to compute fingerprint for PULSE_LICENSE_PUBLIC_KEY." >&2
+            exit 1
+        fi
+        if [[ "${actual_fingerprint}" != "${expected_fingerprint}" ]]; then
+            echo "Error: PULSE_LICENSE_PUBLIC_KEY fingerprint mismatch." >&2
+            echo "Expected: SHA256:${expected_fingerprint}" >&2
+            echo "Actual:   SHA256:${actual_fingerprint}" >&2
+            exit 1
+        fi
+        echo "Verified license public key fingerprint: SHA256:${actual_fingerprint}"
+    fi
+
+    LICENSE_LDFLAGS="-X github.com/rcourtman/pulse-go-rewrite/internal/license.EmbeddedPublicKey=${PULSE_LICENSE_PUBLIC_KEY}"
 fi
 
 # Clean previous builds