SP int: modular exponentiation constant time

SparkiDev · SparkiDev · commit 70422bd38416 · 2025-06-19T09:56:28.000+10:00
Using a 1-bit window size for small exponentsisn't useful.
diff --git a/wolfcrypt/src/sp_int.c b/wolfcrypt/src/sp_int.c
@@ -14207,9 +14207,6 @@ static int _sp_exptmod_nct(const sp_int* b, const sp_int* e, const sp_int* m,
     if (bits > 450) {
         winBits = 6;
     }
-    else if (bits <= 21) {
-        winBits = 1;
-    }
     else if (bits <= 36) {
         winBits = 3;
     }

Original file line number	Diff line number	Diff line change
`@@ -14207,9 +14207,6 @@ static int _sp_exptmod_nct(const sp_int* b, const sp_int* e, const sp_int* m,`
`14207`	`14207`	`if (bits > 450) {`
`14208`	`14208`	`winBits = 6;`
`14209`	`14209`	`}`
`14210`		`- else if (bits <= 21) {`
`14211`		`- winBits = 1;`
`14212`		`- }`
`14213`	`14210`	`else if (bits <= 36) {`
`14214`	`14211`	`winBits = 3;`
`14215`	`14212`	`}`