set3, challenge 22 completed

2 files changed, 36 insertions, 1 deletions

diff --git a/lib/lib3.c b/lib/lib3.c
index 43f3ec6..adea72e 100644
--- a/lib/lib3.c
+++ b/lib/lib3.c
@@ -129,3 +129,35 @@ int mt_19937()
 
 	return (y & 0xFFFFFFFF);
 }
+
+int mt_19937_timestamp_orcale()
+{
+	sleep(random_number_between(40,1000));
+
+	unsigned int seed = time(NULL);
+	printf("timestamp orcale seed: %u\n", seed);
+	mt_19937_seed(seed);
+
+	sleep(random_number_between(40,1000));
+
+	return  mt_19937();
+}
+/***
+  * is there a more clever way to do this than brute force?
+  *
+  **/
+void mt_19937_brute_force_timestamp()
+{
+	unsigned int start = time(NULL);
+	int rnd = mt_19937_timestamp_orcale();
+	unsigned int stop = time(NULL);
+	unsigned int i;
+	// try every seed between start and stop
+	for(i=start;start<=stop;i++) {
+		mt_19937_seed(i);
+		if (rnd == mt_19937()) {
+			printf("found seed: %u\n", i);
+			break;
+		}
+	}
+}
diff --git a/lib/lib3.h b/lib/lib3.h
index 8adbbb9..ee11a15 100644
--- a/lib/lib3.h
+++ b/lib/lib3.h
@@ -5,6 +5,8 @@
 #include <string.h>
 #include <stdlib.h>
 #include <openssl/aes.h>
+#include <unistd.h>
+#include <time.h>
 
 #define BLOCKSIZE 16
 
@@ -29,5 +31,6 @@ int aes_ctr(char *in, int length_in, char *out, char *string_key, char *nonce);
 
 void mt_19937_seed(unsigned int seed);
 int mt_19937();
-
+int mt_19937_timestamp_orcale();
+void mt_19937_brute_force_timestamp();
 #endif