Added strkey

1 files changed, 130 insertions, 0 deletions

diff --git a/other/fun/strkey.c b/other/fun/strkey.c
new file mode 100644
index 00000000..fd1caa87
--- /dev/null
+++ b/other/fun/strkey.c
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+/* strkey -- String in Public Key
+ *
+ * Generates Tox's key pairs, checking if a certain string is in the public key.
+ *
+ * Requires sodium or nacl library.
+ *
+ * There seem to be some problems with the code working on Windows -- it works
+ * when built in debug mode with MinGW 4.8, but it doesn't work correctly when
+ * built in release.
+ *
+ * Usage: strkey <offset> <string>
+ *
+ * Offset - an integer specifying exact byte offset position of the string you
+ * are looking for within a public key. When offset is negative, the program
+ * just looks for the desired string being somewhere, doesn't matter where, in
+ * the public key.
+ *
+ * String - a hex string that you want to have in your public key. It must have
+ * an even number of letters, since every two hexes map to a single byte of
+ * the public key.
+ *
+ * Examples:
+ *   strkey 0 0123
+ *   Looks for a public key that begins with "0123".
+ *
+ *   strkey 1 0123
+ *   Looks for a public key that has "0123" starting at its second byte, i.e. "XX0123...".
+ *
+ *   strkey 2 0123
+ *   Looks for a public key that has "0123" starting at its third byte, i.e. "XXXX0123...".
+ *   (each two hexes represent a single byte of a public key)
+ *
+ *   strkey -1 AF57CC
+ *   Looks for a public key that contains "AF57CC", regardless of its position.
+ *
+ * To compile with gcc and sodium: gcc strkey.c -o strkey -lsodium
+*/
+
+#include <stdio.h>
+#include <string.h>
+
+#include <sodium.h>
+
+#define PRINT_TRIES_COUNT
+
+void print_key(unsigned char *key)
+{
+    size_t i;
+    for (i = 0; i < crypto_box_PUBLICKEYBYTES; i++) {
+        if (key[i] < 16) {
+            fprintf(stdout, "0");
+        }
+
+        fprintf(stdout, "%hhX", key[i]);
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    unsigned char public_key[crypto_box_PUBLICKEYBYTES + 1]; // null terminator
+    unsigned char secret_key[crypto_box_SECRETKEYBYTES];
+    int offset = 0;
+    size_t len;
+    unsigned char desired_bin[crypto_box_PUBLICKEYBYTES + 1]; // null terminator
+
+    if (argc == 3) {
+        offset = atoi(argv[1]);
+        char *desired_hex = argv[2];
+        len = strlen(desired_hex);
+        if (len % 2 != 0) {
+            fprintf(stderr, "Desired key should have an even number of letters\n");
+            exit(1);
+        }
+        size_t block_length = (offset < 0 ? 0 : offset) + len/2;
+        if (block_length > crypto_box_PUBLICKEYBYTES) {
+            fprintf(stderr, "The given key with the given offset exceed public key's length\n");
+            exit(1);
+        }
+
+        // convert hex to bin
+        char *pos = desired_hex;
+        size_t i;
+        for (i = 0; i < len; pos += 2) {
+            sscanf(pos, "%2hhx", &desired_bin[i]);
+            ++i;
+        }
+    } else {
+        fprintf(stdout, "Usage: executable <byte offset> <desired hex string with even number of letters>\n");
+        exit(1);
+    }
+
+    desired_bin[len/2] = '\0';
+    public_key[crypto_box_PUBLICKEYBYTES + 1] = '\0';
+
+#ifdef PRINT_TRIES_COUNT
+    long long unsigned int tries = 0;
+#endif
+
+    if (offset < 0) {
+        do {
+#ifdef PRINT_TRIES_COUNT
+            tries ++;
+#endif
+            crypto_box_keypair(public_key, secret_key);
+        } while (strstr(public_key, desired_bin) == 0);
+    } else {
+        unsigned char *p = public_key  + offset;
+        len /= 2;
+        do {
+#ifdef PRINT_TRIES_COUNT
+            tries ++;
+#endif
+            crypto_box_keypair(public_key, secret_key);
+        } while (memcmp(p, desired_bin, len) != 0);
+    }
+
+    fprintf(stdout, "Public key:  ");
+    print_key(public_key);
+    fprintf(stdout, "\n");
+
+    fprintf(stdout, "Private key: ");
+    print_key(secret_key);
+    fprintf(stdout, "\n");
+
+#ifdef PRINT_TRIES_COUNT
+        fprintf(stdout, "Found the key pair on %llu try.\n", tries);
+#endif
+
+    return 0;
+}
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