For DH, use standard primes from RFCs

[exim.git] / src / util / gen_pkcs3.c

diff --git a/src/util/gen_pkcs3.c b/src/util/gen_pkcs3.c
new file mode 100644 (file)
index 0000000..ae7e761
--- /dev/null
+++ b/src/util/gen_pkcs3.c
@@ -0,0 +1,229 @@
+/* Copyright (C) 2012 Phil Pennock.
+ * This is distributed as part of Exim and licensed under the GPL.
+ * See the file "NOTICE" for more details.
+ */
+
+/* Build with:
+ * c99 $(pkg-config --cflags openssl) gen_pkcs3.c $(pkg-config --libs openssl)
+ */
+
+#include <ctype.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <openssl/bio.h>
+#include <openssl/bn.h>
+#include <openssl/dh.h>
+#include <openssl/err.h>
+#include <openssl/pem.h>
+
+extern const char *__progname;
+
+
+void __attribute__((__noreturn__)) __attribute__((__format__(printf, 1, 2)))
+die(const char *fmt, ...)
+{
+  va_list ap;
+
+  fflush(NULL);
+  fprintf(stderr, "%s: ", __progname);
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+  fprintf(stderr, "\n");
+  fflush(stderr);
+  exit(1);
+}
+
+
+void __attribute__((__noreturn__))
+die_openssl_err(const char *msg)
+{
+  char err_string[250];
+  unsigned long e;
+
+  ERR_error_string_n(ERR_get_error(), err_string, sizeof(err_string));
+  die("%s: %s", msg, err_string);
+}
+
+
+static BIGNUM *
+bn_from_text(const char *text)
+{
+  BIGNUM *b;
+  char *p, *spaceless;
+  const char *q, *end;
+  size_t len;
+  int rc;
+
+  len = strlen(text);
+  spaceless = malloc(len);
+  if (!spaceless)
+    die("malloc(%zu) failed: %s", len, strerror(errno));
+
+  for (p = spaceless, q = text, end = text + len;
+       q < end;
+       ++q) {
+    if (!isspace(*q))
+      *p++ = *q;
+  }
+
+  b = NULL;
+  rc = BN_hex2bn(&b, spaceless);
+
+  if (rc != p - spaceless)
+    die("BN_hex2bn did not convert entire input; took %d of %z bytes",
+        rc, p - spaceless);
+
+  return b;
+}
+
+
+static void
+our_dh_check(DH *dh)
+{
+  int rc, errflags = 0;
+
+  rc = DH_check(dh, &errflags);
+  if (!rc) die_openssl_err("DH_check() could not be performed");;
+
+  /* We ignore DH_UNABLE_TO_CHECK_GENERATOR because some of the invocations
+   * deliberately provide generators other than 2 or 5. */
+
+  if (errflags & DH_CHECK_P_NOT_SAFE_PRIME)
+    die("DH_check(): p not a safe prime");
+  if (errflags & DH_NOT_SUITABLE_GENERATOR)
+    die("DH_check(): g not suitable as generator");
+}
+
+
+static void
+emit_c_format_dh(FILE *stream, DH *dh)
+{
+  BIO *bio;
+  long length;
+  char *data, *end, *p, *nl;
+
+  bio = BIO_new(BIO_s_mem());
+  PEM_write_bio_DHparams(bio, dh);
+  length = BIO_get_mem_data(bio, &data);
+  if (!length)
+    die("no data in memory BIO to format for printing");
+  if (length < 0)
+    die("grr, negative length memory not supported");
+  end = data + length;
+
+  for (p = data; p < end; /**/) {
+    nl = strchr(p, '\n');
+    if (!nl) {
+      fprintf(stream, "\"%s\\n\"\n/* missing final newline */\n", p);
+      break;
+    }
+    *nl = '\0';
+    fprintf(stream, "\"%s\\n\"\n", p);
+    p = nl + 1;
+  }
+}
+
+
+void __attribute__((__noreturn__))
+usage(FILE *stream, int exitcode)
+{
+  fprintf(stream, "Usage: %s [-CPcst] <dh_p> <dh_g>\n"
+"Both dh_p and dh_g should be hex strings representing the numbers\n"
+"They may contain whitespace.\n"
+"\n"
+" -C      show C string form of PEM result\n"
+" -P      do not show PEM\n"
+" -c      run OpenSSL DH_check() on the DH object\n"
+" -s      show the parsed p and g\n"
+" -t      show text form of certificate\n"
+
+      , __progname);
+  exit(exitcode);
+}
+
+
+int
+main(int argc, char *argv[])
+{
+  BIGNUM *p, *g;
+  DH *dh;
+  int ch;
+  bool perform_dh_check = false;
+  bool show_c_form = false;
+  bool show_numbers = false;
+  bool show_pem = true;
+  bool show_text = false;
+
+  while ((ch = getopt(argc, argv, "CPcsth")) != -1) {
+    switch (ch) {
+      case 'C':
+        show_c_form = true;
+        break;
+      case 'P':
+        show_pem = false;
+        break;
+      case 'c':
+        perform_dh_check = true;
+        break;
+      case 's':
+        show_numbers = true;
+        break;
+      case 't':
+        show_text = true;
+        break;
+
+      case 'h':
+        usage(stdout, 0);
+      case '?':
+        die("Unknown option or missing argument -%c", optopt);
+      default:
+        die("Unhandled option -%c", ch);
+    }
+  }
+
+  optind -= 1;
+  argc -= optind;
+  argv += optind;
+
+  if (argc != 3) {
+    fprintf(stderr, "argc: %d\n", argc);
+    usage(stderr, 1);
+  }
+
+  p = bn_from_text(argv[1]);
+  g = bn_from_text(argv[2]);
+
+  if (show_numbers) {
+    printf("p = ");
+    BN_print_fp(stdout, p);
+    printf("\ng = ");
+    BN_print_fp(stdout, g);
+    printf("\n");
+  }
+
+  dh = DH_new();
+  dh->p = p;
+  dh->g = g;
+
+  if (perform_dh_check)
+    our_dh_check(dh);
+
+  if (show_text)
+    DHparams_print_fp(stdout, dh);
+
+  if (show_pem) {
+    if (show_c_form)
+      emit_c_format_dh(stdout, dh);
+    else
+      PEM_write_DHparams(stdout, dh);
+  }
+
+  DH_free(dh); /* should free p & g too */
+  return 0;
+}