--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Meerwald-dir/cmp_zhu_sig.c	Fri Dec 20 13:08:59 2024 +0100
@@ -0,0 +1,211 @@
+#include "wm.h"
+
+char *progname;
+
+void usage(void) {
+  fprintf(stderr, "usage: %s [-h] [-C] [-o file] [-v n] -s file file\n\n", progname);
+  fprintf(stderr, "\t-C\t\toutput correlation only\n");
+  fprintf(stderr, "\t-h\t\tprint usage\n");
+  fprintf(stderr, "\t-o file\t\toutput file\n");
+  fprintf(stderr, "\t-v n\t\tverbosity level\n");
+  fprintf(stderr, "\t-s file\t\toriginal signature file\n");
+  exit(0);
+}
+
+int main(int argc, char *argv[]) {
+
+  FILE *in = stdin;
+  FILE *out = stdout;
+  FILE *sig = NULL;
+
+  char signature_name[MAXPATHLEN];
+  char output_name[MAXPATHLEN] = "(stdout)";
+  char input_name[MAXPATHLEN] = "(stdin)";
+
+  int c, i, j, n;
+  int in_level;
+  double *cumul_watermark, *orig_watermark;
+  int *cumul_watermark_count;
+  int sig_n, in_n;
+  double sig_a;
+  int sig_l;
+  int sig_e, sig_f;
+  char line[32];
+  double correlation, maxcorrelation;
+  double s1, s2, s3;
+
+  int verbose = 0;
+  int correlation_only = 0;
+
+  progname = argv[0];
+
+  while ((c = getopt(argc, argv, "h?Co:s:v:")) != EOF) {
+    switch (c) {
+      case 'h':
+      case '?':
+        usage();
+        break;
+      case 'C':
+        correlation_only = 1;
+        break;
+      case 'o':
+        if ((out = fopen(optarg, "w")) == NULL) {
+          fprintf(stderr, "%s: unable to open output file %s\n", progname, optarg);
+          exit(1);
+        }
+        strcpy(output_name, optarg);
+        break;
+      case 's':
+        if ((sig = fopen(optarg, "r")) == NULL) {
+          fprintf(stderr, "%s: unable to open signature file %s\n", progname, optarg);
+          exit(1);
+        }
+        strcpy(signature_name, optarg);
+        break;
+     case 'v':
+        verbose = atoi(optarg);
+        if (verbose < 0) {
+          fprintf(stderr, "%s: verbosity level %d out of range\n", progname, verbose);
+          exit(1);
+        }
+        break;
+    }
+  }
+
+  argc -= optind;
+  argv += optind;
+
+  if (argc > 1) {
+    usage();
+    exit(1);
+  }
+
+  if (argc == 1 && *argv[0] != '-') {
+    if ((in = fopen(argv[0], "r")) == NULL) {
+      fprintf(stderr, "%s: unable to open input file %s\n", progname, argv[0]);
+      exit(1);
+    }
+    else
+      strcpy(input_name, argv[0]);
+  }
+  
+  if (!sig) {
+    fprintf(stderr, "%s: original signature file not specified, use -s file option\n", progname);
+    exit(1);
+  }
+
+  fgets(line, sizeof(line), sig);
+  if (strspn(line, "ZHSG") < 4) {
+    fprintf(stderr, "%s: original signature file %s invalid\n", progname, signature_name);
+    exit(1);
+  }
+
+  fgets(line, sizeof(line), in);
+  if (strspn(line, "ZHWM") < 4) {
+    fprintf(stderr, "%s: watermark file %s invalid\n", progname, input_name);
+    exit(1);
+  }
+
+  fscanf(sig, "%d\n", &sig_n);
+  fscanf(in, "%d\n", &in_n);
+  if (sig_n != in_n) {
+    fprintf(stderr, "%s: watermark length mismatch (original %d, input %d)\n", progname, sig_n, in_n);
+    exit(1);
+  }
+  if (sig_n <= 0 || sig_n > 32000) {
+    fprintf(stderr, "%s: invalid original watermark length %d\n", progname, sig_n);
+    exit(1);
+  }
+  if (in_n != sig_n) {
+    fprintf(stderr, "%s: invalid watermark length %d, does not match signature length\n", progname, in_n);
+    exit(1);
+  }
+
+  fscanf(sig, "%lf\n", &sig_a);
+  fscanf(sig, "%d\n", &sig_l);
+  fscanf(sig, "%d\n", &sig_e);
+  fscanf(sig, "%d\n", &sig_f);
+  fscanf(sig, "%*[^\n\r]\n");
+
+  orig_watermark = malloc(sig_n * sizeof(double));
+  for (i = 0; i < sig_n; i++) 
+    fscanf(sig, "%lf\n", &orig_watermark[i]);
+  fclose(sig);
+
+  fscanf(in, "%d\n", &in_level);
+
+  cumul_watermark = malloc(in_n * sizeof(double));
+  cumul_watermark_count = malloc(in_n * sizeof(int));
+
+  for (i = 0; i < in_n; i++) {
+    cumul_watermark_count[i] = 0;
+    cumul_watermark[i] = 0.0;
+  }
+
+  /*
+   * normalized correlation
+   * Craver, S., "Can Invisible Watermarks Resolve Rightful Ownership?", IBM Research Report, 1996, p. 5
+   */
+  maxcorrelation = -10000.0;
+  for (i = 0; i < in_level; i++) {
+    fscanf(in, "%d\n", &n);
+
+    s1 = s2 = s3 = 0.0;
+    for (j = 0; j < n; j++) {
+      double in_x, sig_x;
+
+      sig_x = orig_watermark[j];
+      fscanf(in, "%lf\n", &in_x);
+
+      s1 += sig_x * in_x;
+      s2 += in_x * in_x;
+      s3 += sig_x * sig_x;
+
+      if (verbose > 2) 
+        fprintf(stderr, "%s: level %d; orig %f input %f\n", progname, i, sig_x, in_x);
+
+      cumul_watermark[j % in_n] += in_x;
+      cumul_watermark_count[j % in_n]++;      
+    }
+
+    correlation = s1 / sqrt(s2 * s3);
+    if (correlation > maxcorrelation)
+      maxcorrelation = correlation; 
+
+    if (!correlation_only)
+      fprintf(out, "%s: correlation level %d: %f\n", progname, i, correlation);
+  }
+
+  s1 = s2 = s3 = 0.0;
+  for (i = 0; i < in_n; i++) {
+    double in_x, sig_x;
+
+    in_x = cumul_watermark[i] / (double) cumul_watermark_count[i];
+    sig_x = orig_watermark[i];
+
+    s1 += sig_x * in_x;
+    s2 += in_x * in_x;
+    s3 += sig_x * sig_x;
+  }
+
+  correlation = s1 / sqrt(s2 * s3);
+  if (!correlation_only)
+    fprintf(out, "%s: cumultative correlation: %f\n", progname, correlation);
+
+  if (correlation > maxcorrelation)
+    maxcorrelation = correlation; 
+    
+  if (!correlation_only)
+    fprintf(out, "%s: max. correlation: %f\n", progname, maxcorrelation);
+  else
+    fprintf(out, "%f\n", maxcorrelation);
+
+  fclose(out);
+  fclose(in);
+
+  free(orig_watermark);
+  free(cumul_watermark);
+  free(cumul_watermark_count);
+
+  exit(0);
+}