2 files changed, 55 insertions, 0 deletions
diff --git a/src/tools/Makefile.am b/src/tools/Makefile.am
index 7d7f2c7b8f..79393d6854 100644
--- a/src/tools/Makefile.am
+++ b/src/tools/Makefile.am
@@ -1,4 +1,5 @@
 bin_PROGRAMS = tor-resolve tor-gencert
+noinst_PROGRAMS =  tor-checkkey
 
 tor_resolve_SOURCES = tor-resolve.c
 tor_resolve_LDFLAGS = @TOR_LDFLAGS_libevent@
@@ -10,3 +11,8 @@ tor_gencert_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \
 tor_gencert_LDADD = ../common/libor.a ../common/libor-crypto.a \
         -lz -lcrypto -levent @TOR_LIB_WS32@ @TOR_LIB_GDI@
 
+tor_checkkey_SOURCES = tor-checkkey.c
+tor_checkkey_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \
+        @TOR_LDFLAGS_libevent@
+tor_checkkey_LDADD = ../common/libor.a ../common/libor-crypto.a \
+        -lz -lcrypto -levent @TOR_LIB_WS32@ @TOR_LIB_GDI@
diff --git a/src/tools/tor-checkkey.c b/src/tools/tor-checkkey.c
new file mode 100644
index 0000000000..e0be6d7287
--- /dev/null
+++ b/src/tools/tor-checkkey.c
@@ -0,0 +1,49 @@
+
+#define CRYPTO_PRIVATE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "crypto.h"
+#include "log.h"
+#include "util.h"
+#include "compat.h"
+#include <openssl/bn.h>
+#include <openssl/rsa.h>
+
+int main(int c, char **v)
+{
+  crypto_pk_env_t *env;
+  char *str;
+  RSA *rsa;
+  init_logging();
+
+  if (c < 2) {
+    fprintf(stderr, "Hi. I'm tor-checkkey.  Tell me a filename that has a PEM-encoded RSA public key (like in a cert) and I'll dump the modulus.\n");
+    return 1;
+  }
+
+  if (crypto_global_init(0)) {
+    fprintf(stderr, "Couldn't initialize crypto library.\n");
+    return 1;
+  }
+
+  str = read_file_to_str(v[1], 0, NULL);
+  if (!str) {
+    fprintf(stderr, "Couldn't read %s\n", v[1]);
+    return 1;
+  }
+
+  env = crypto_new_pk_env();
+  if (crypto_pk_read_public_key_from_string(env, str, strlen(str))<0) {
+    fprintf(stderr, "Couldn't parse key.\n");
+    return 1;
+  }
+  tor_free(str);
+
+  rsa = _crypto_pk_env_get_rsa(env);
+  str = BN_bn2hex(rsa->n);
+
+  printf("%s\n", str);
+
+  return 0;
+}