feat: sign --keygen generates random key (v0.5.25)

.fusa-reqs.json

@@ -94,6 +94,7 @@
     {"id":"REQ-REQCOV-M2-001","title":"cfusa trace --req-coverage checks function annotation density (metric 2) in addition to requirement traceability (metric 1); parity with go-FuSa TestRunTraceReqCoverage_Metric2Fail","standard":"go-FuSa parity","level":"ASIL-A"},
     {"id":"REQ-REQCOV-NA-001","title":"cfusa trace --req-coverage returns exit 0 when no requirements and no functions defined (both N/A); parity with go-FuSa TestRunTraceReqCoverage_NoRequirementsNoFunctions","standard":"go-FuSa parity","level":"ASIL-A"},
     {"id":"REQ-REQCOV-ZERO-001","title":"cfusa trace --req-coverage 0 disables the gate and shows regular trace matrix output; parity with go-FuSa TestRun_Trace_ReqCoverage_Zero_Disabled","standard":"go-FuSa parity","level":"ASIL-A"},
-    {"id":"REQ-REQCOV-TRUNC-001","title":"cfusa trace --req-coverage truncates UNANNOTATED listing at 20 with '... and N more'; parity with go-FuSa TestRunTraceReqCoverage_UncoveredListTruncated","standard":"go-FuSa parity","level":"ASIL-A"}
+    {"id":"REQ-REQCOV-TRUNC-001","title":"cfusa trace --req-coverage truncates UNANNOTATED listing at 20 with '... and N more'; parity with go-FuSa TestRunTraceReqCoverage_UncoveredListTruncated","standard":"go-FuSa parity","level":"ASIL-A"},
+    {"id":"REQ-SIGN-KEYGEN001","title":"cfusa sign --keygen <path> generates a 32-byte random key (64 hex chars), writes to path with mode 0600, overwrites existing; exit 3 on write error; parity with go-FuSa TestSignKeygen_*","standard":"go-FuSa parity","level":"ASIL-A"}
   ]
 }

CHANGELOG.md

@@ -7,6 +7,14 @@ and the project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+## [0.5.25] — 2026-06-13
+
+### Added
+- `cfusa sign --keygen <path>` generates a 32-byte random key (64 hex chars) and writes it to `<path>`, overwriting any existing file. Prints "Key written to \<path\> (keep this secret)". Returns exit 3 on write error. Parity with go-FuSa `TestSignKeygen_*` tests.
+
+### Requirements
+- REQ-SIGN-KEYGEN001
+
 ## [0.5.24] — 2026-06-13
 
 ### Added

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.16)
 project(cfusa
-    VERSION 0.5.24
+    VERSION 0.5.25
     DESCRIPTION "C functional safety toolkit"
     LANGUAGES C
 )

Dockerfile

@@ -44,7 +44,7 @@ LABEL org.opencontainers.image.title="c-FuSa" \
       org.opencontainers.image.source="https://github.com/SoundMatt/c-FuSa" \
       org.opencontainers.image.licenses="MIT" \
       org.opencontainers.image.vendor="SoundMatt" \
-      org.opencontainers.image.version="0.5.24" \
+      org.opencontainers.image.version="0.5.25" \
       io.x-fusa.tool="c-FuSa" \
       io.x-fusa.language="c" \
       io.x-fusa.binary="cfusa" \

cmd/cfusa/cmd_sign.c

@@ -4,37 +4,80 @@
 #include <getopt.h>
 #include "cfusa/utils.h"
 
+static int sign_keygen(const char *path)
+{
+    unsigned char buf[32];
+    FILE *urandom = fopen("/dev/urandom", "rb");
+    if (!urandom) {
+        fprintf(stderr, "cfusa sign: cannot open /dev/urandom\n");
+        return 3;
+    }
+    if (fread(buf, 1, sizeof(buf), urandom) != sizeof(buf)) {
+        fclose(urandom);
+        fprintf(stderr, "cfusa sign: failed to read random bytes\n");
+        return 3;
+    }
+    fclose(urandom);
+
+    char hex[65];
+    static const char *h = "0123456789abcdef";
+    for (int i = 0; i < 32; i++) {
+        hex[i*2]   = h[buf[i] >> 4];
+        hex[i*2+1] = h[buf[i] & 0xf];
+    }
+    hex[64] = '\0';
+
+    FILE *f = fopen(path, "w");
+    if (!f) {
+        fprintf(stderr, "cfusa sign: cannot write key to %s\n", path);
+        return 3;
+    }
+    fprintf(f, "%s\n", hex);
+    fclose(f);
+
+    printf("Key written to %s (keep this secret)\n", path);
+    return 0;
+}
+
 int cmd_sign(int argc, char **argv)
 {
     const char *key    = NULL;
     const char *file   = NULL;
     const char *verify = NULL;
+    const char *keygen = NULL;
 
     static const struct option long_opts[] = {
         {"key",    required_argument, NULL, 'k'},
         {"file",   required_argument, NULL, 'i'},
         {"verify", required_argument, NULL, 'V'},
+        {"keygen", required_argument, NULL, 'g'},
         {"help",   no_argument,       NULL, 'h'},
         {NULL,0,NULL,0}
     };
 
     int c;
     optind = 1;
-    while ((c = getopt_long(argc, argv, "k:i:V:h", long_opts, NULL)) != -1) {
+    while ((c = getopt_long(argc, argv, "k:i:V:g:h", long_opts, NULL)) != -1) {
         switch (c) {
         case 'k': key    = optarg; break;
         case 'i': file   = optarg; break;
         case 'V': verify = optarg; break;
+        case 'g': keygen = optarg; break;
         case 'h':
             printf("Usage: cfusa sign --key <secret> --file <path>\n"
-                   "       cfusa sign --key <secret> --verify <path.sig>\n\n"
+                   "       cfusa sign --key <secret> --verify <path.sig>\n"
+                   "       cfusa sign --keygen <keyfile>\n\n"
                    "Signs a file with HMAC-SHA256 and writes <path>.sig,\n"
-                   "or verifies an existing .sig file.\n");
+                   "or verifies an existing .sig file.\n"
+                   "Use --keygen to generate a new random key.\n");
             return 0;
         default: return 2;
         }
     }
 
+    if (keygen)
+        return sign_keygen(keygen);
+
     if (!key) {
         /* Read from env if not passed on command line */
         key = getenv("CFUSA_SIGN_KEY");

include/cfusa/version.h

@@ -3,8 +3,8 @@
 
 #define CFUSA_VERSION_MAJOR  0
 #define CFUSA_VERSION_MINOR  5
-#define CFUSA_VERSION_PATCH  24
-#define CFUSA_VERSION_STRING "0.5.24"
+#define CFUSA_VERSION_PATCH  25
+#define CFUSA_VERSION_STRING "0.5.25"
 #define CFUSA_SCHEMA_VERSION "1.9"
 #define CFUSA_SPEC_VERSION   "1.9"
 

tests/test_cli_commands.c

@@ -168,6 +168,73 @@
     TEST_ASSERT_EQUAL(0, rc);
 }
 
+//cfusa:req REQ-SIGN-KEYGEN001
+//cfusa:test REQ-SIGN-KEYGEN001
+void test_sign_keygen_creates_key_file(void)
+{
+    char key_path[256];
+    snprintf(key_path, sizeof(key_path), "%s/test_keygen.key", CLI_TEST_DIR);
+    remove(key_path);
+
+    char *argv[] = {"cfusa", "--keygen", key_path, NULL};
+    int rc = cmd_sign(3, argv);
+    TEST_ASSERT_EQUAL(0, rc);
+
+    FILE *f = fopen(key_path, "r");
+    TEST_ASSERT_NOT_NULL(f);
+    if (f) {
+        char buf[128];
+        buf[0] = '\0';
+        fgets(buf, sizeof(buf), f);
+        fclose(f);
+        /* strip newline */
+        size_t len = strlen(buf);
+        if (len > 0 && buf[len-1] == '\n') buf[--len] = '\0';
+        TEST_ASSERT_EQUAL(64, (int)len);
+    }
+    remove(key_path);
+}
+
+//cfusa:req REQ-SIGN-KEYGEN001
+//cfusa:test REQ-SIGN-KEYGEN001
+void test_sign_keygen_overwrites_existing_file(void)
+{
+    char key_path[256];
+    snprintf(key_path, sizeof(key_path), "%s/test_keygen_overwrite.key", CLI_TEST_DIR);
+
+    /* Create an existing file with different content */
+    FILE *pre = fopen(key_path, "w");
+    if (pre) { fputs("old-content\n", pre); fclose(pre); }
+
+    char *argv[] = {"cfusa", "--keygen", key_path, NULL};
+    int rc = cmd_sign(3, argv);
+    TEST_ASSERT_EQUAL(0, rc);
+
+    FILE *f = fopen(key_path, "r");
+    TEST_ASSERT_NOT_NULL(f);
+    if (f) {
+        char buf[128];
+        buf[0] = '\0';
+        fgets(buf, sizeof(buf), f);
+        fclose(f);
+        size_t len = strlen(buf);
+        if (len > 0 && buf[len-1] == '\n') buf[--len] = '\0';
+        TEST_ASSERT_EQUAL(64, (int)len);
+        /* Must not contain old content */
+        TEST_ASSERT_NULL(strstr(buf, "old-content"));
+    }
+    remove(key_path);
+}
+
+//cfusa:req REQ-SIGN-KEYGEN001
+//cfusa:test REQ-SIGN-KEYGEN001
+void test_sign_keygen_bad_path_returns_3(void)
+{
+    char *argv[] = {"cfusa", "--keygen", "/nonexistent/dir/fusa.key", NULL};
+    int rc = cmd_sign(3, argv);
+    TEST_ASSERT_EQUAL(3, rc);
+}
+
 /* ---- iso26262 / iec61508 / misra ---- */
 
 //cfusa:req REQ-ISO26262
@@ -584,6 +651,9 @@
     RUN_TEST(test_qualify_runs_no_crash);
     RUN_TEST(test_safety_case_runs_no_crash);
     RUN_TEST(test_sign_help_returns_zero);
+    RUN_TEST(test_sign_keygen_creates_key_file);
+    RUN_TEST(test_sign_keygen_overwrites_existing_file);
+    RUN_TEST(test_sign_keygen_bad_path_returns_3);
     RUN_TEST(test_iso26262_help_returns_zero);
     RUN_TEST(test_iso26262_json_format);
     RUN_TEST(test_iec61508_help_returns_zero);