Contextualize comment about mbedtls_mpi_random retries
This comment is no longer in the specific context of generating a
random point on an elliptic curve.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/bignum.c b/library/bignum.c
index 6c3f127..a995bbe 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -2498,9 +2498,11 @@
* a probability 1/2 of being 0, and then the result will be < N),
* so after 30 tries failure probability is a most 2**(-30).
*
- * For most curves, 1 try is enough with overwhelming probability,
- * since N starts with a lot of 1s in binary, but some curves
- * such as secp224k1 are actually very close to the worst case.
+ * When N is just below a power of 2, as is the case when generating
+ * a random point on most elliptic curves, 1 try is enough with
+ * overwhelming probability. When N is just above a power of 2,
+ * as when generating a random point on secp224k1, each try has
+ * a probability of failing that is almost 1/2.
*/
if( ++count > 30 )
{