/*
* Verify that d*e is congruent to 1 mod (p-1), and mod
* (q-1). This is equivalent to it being congruent to 1 mod
- * lcm(p-1,q-1), i.e. congruent to 1 mod phi(n). Note that
- * phi(n) is _not_ simply (p-1)*(q-1).
+ * lambda(n) = lcm(p-1,q-1). The usual `textbook' condition,
+ * that d e == 1 (mod (p-1)(q-1)) is sufficient, but not
+ * actually necessary.
*/
mpz_mul(&tmp, &d, &e);
mpz_sub_ui(&tmp2, &st->p, 1);