+
+/*
+ * A Bignum is stored as a sequence of `unsigned short' words. The
+ * first tells how many remain; the remaining ones are digits, LS
+ * first.
+ */
+typedef unsigned short *Bignum;
+
+Bignum newbn(int length);
+void freebn(Bignum b);
+void modpow(Bignum base, Bignum exp, Bignum mod, Bignum result);
+
+Bignum dh_create_e(void);
+Bignum dh_find_K(Bignum f);