+#define B64_SIZE(len) ((len) * 4 / 3 + 5)
+#define HEX_SIZE(len) ((len) * 2 + 1)
+
+extern size_t hex2bin(const char *src, void *dst, size_t length);
+extern size_t bin2hex(const void *src, char *dst, size_t length);
+
+// Returns true if string represents a base-10 integer.
+extern bool is_decimal(const char *str);
+
+// The reverse of atoi().
+extern char *int_to_str(int num);
+
+extern size_t b64encode_tinc(const void *src, char *dst, size_t length);
+extern size_t b64encode_tinc_urlsafe(const void *src, char *dst, size_t length);
+extern size_t b64decode_tinc(const char *src, void *dst, size_t length);
+
+#ifdef HAVE_WINDOWS