better nonce generation and session credentials verification

based on the patch from Chris Davies

Signed-off-by: Michael Krelin <hacker@klever.net>

4 files changed, 36 insertions, 7 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 09f698e..b5b7d5c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -9,3 +9,3 @@ AM_CPPFLAGS = ${CPPFLAGS_DEBUG} \
 DEFAULT_INCLUDES = -I${top_builddir} -I${builddir} -I${srcdir}
-INCLUDES = ${MODULES_CFLAGS}
+INCLUDES = ${MODULES_CFLAGS} ${UUID_CFLAGS}
 
@@ -17,3 +17,3 @@ nodist_iiid_SOURCES = \
 	COPYING.cc
-iiid_LDADD = ${MODULES_LIBS}
+iiid_LDADD = ${MODULES_LIBS} ${UUID_LIBS}
 
diff --git a/src/eyefiservice.cc b/src/eyefiservice.cc
index d233a07..1a21c02 100644
--- a/src/eyefiservice.cc
+++ b/src/eyefiservice.cc
@@ -8,2 +8,3 @@
 #include <autosprintf.h>
+#include <openssl/rand.h>
 #include "eyekinfig.h"
@@ -12,2 +13,4 @@
 
+static binary_t session_nonce;
+
 static bool detached_child() {
@@ -48,5 +51,4 @@ int eyefiService::StartSession(
     r.credential = binary_t(macaddress+cnonce+eyekinfig_t(macaddress).get_upload_key()).md5().hex();
-    /* TODO: better nonce generator */
-    time_t t = time(0);
-    r.snonce = binary_t(&t,sizeof(t)).md5().hex();
+
+    r.snonce = session_nonce.make_nonce().hex();
     r.transfermode=transfermode;
@@ -76,5 +78,14 @@ int eyefiService::GetPhotoStatus(
     syslog(LOG_DEBUG,
-	    "GetPhotoStatus request from %s with credential=%s, filename=%s, filesize=%ld, filesignature=%s",
-	    macaddress.c_str(), credential.c_str(), filename.c_str(), filesize, filesignature.c_str() );
+	    "GetPhotoStatus request from %s with credential=%s, filename=%s, filesize=%ld, filesignature=%s; session nonce=%s",
+	    macaddress.c_str(), credential.c_str(), filename.c_str(), filesize, filesignature.c_str(), session_nonce.hex().c_str() );
+#endif
+
+    std::string computed_credential = binary_t(macaddress+eyekinfig_t(macaddress).get_upload_key()+session_nonce.hex()).md5().hex();
+
+#ifndef NDEBUG
+    syslog(LOG_DEBUG, " computed credential=%s", computed_credential.c_str());
 #endif
+
+    if (credential != computed_credential) throw std::runtime_error("card authentication failed");
+
     r.fileid = 1; r.offset = 0;
diff --git a/src/eyetil.cc b/src/eyetil.cc
index fe816a6..7669cb6 100644
--- a/src/eyetil.cc
+++ b/src/eyetil.cc
@@ -11,2 +11,7 @@
 
+#include "config.h"
+#ifdef HAVE_LIBUUID
+# include <uuid/uuid.h>
+#endif
+
 binary_t& binary_t::from_hex(const std::string& h) {
@@ -34,2 +39,14 @@ binary_t& binary_t::from_data(const void *d,size_t s) {
 
+binary_t& binary_t::make_nonce() {
+#ifdef HAVE_LIBUUID
+    uuid_t uuid;
+    uuid_generate(uuid);
+    from_data((unsigned char*)uuid,sizeof(uuid));
+#else
+    resize(16);
+    std::generate_n(begin(),16,rand);
+#endif /* HAVE_LIBUUID */
+    return *this;
+}
+
 std::string binary_t::hex() const {
diff --git a/src/eyetil.h b/src/eyetil.h
index 378f703..d946e71 100644
--- a/src/eyetil.h
+++ b/src/eyetil.h
@@ -17,2 +17,3 @@ class binary_t : public std::vector<unsigned char> {
 	binary_t& from_data(const void *d,size_t s);
+	binary_t& make_nonce();