Merge pull request #2063 from botovq/bn_mod_sqrt

Enable BN_mod_sqrt() for upcoming LibreSSL 3.8.2
sfackler · Oct 20, 2023 · f58467b · f58467b
2 parents 0917bed + c84e3fc
commit f58467b
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Showing 2 changed files with 11 additions and 7 deletions.
diff --git a/openssl-sys/src/handwritten/bn.rs b/openssl-sys/src/handwritten/bn.rs
@@ -75,7 +75,6 @@ extern "C" {
         m: *const BIGNUM,
         ctx: *mut BN_CTX,
     ) -> c_int;
-    #[cfg(ossl110)]
     pub fn BN_mod_sqrt(
         ret: *mut BIGNUM,
         a: *const BIGNUM,

diff --git a/openssl/src/bn.rs b/openssl/src/bn.rs
@@ -655,7 +655,6 @@ impl BigNumRef {
 
     /// Places into `self` the modular square root of `a` such that `self^2 = a (mod p)`
     #[corresponds(BN_mod_sqrt)]
-    #[cfg(ossl110)]
     pub fn mod_sqrt(
         &mut self,
         a: &BigNumRef,
@@ -1490,17 +1489,23 @@ mod tests {
         assert!(b.is_const_time())
     }
 
-    #[cfg(ossl110)]
     #[test]
     fn test_mod_sqrt() {
         let mut ctx = BigNumContext::new().unwrap();
 
-        let s = BigNum::from_hex_str("47A8DD7626B9908C80ACD7E0D3344D69").unwrap();
-        let p = BigNum::from_hex_str("81EF47265B58BCE5").unwrap();
+        let s = BigNum::from_hex_str("2").unwrap();
+        let p = BigNum::from_hex_str("7DEB1").unwrap();
+        let mut sqrt = BigNum::new().unwrap();
         let mut out = BigNum::new().unwrap();
 
-        out.mod_sqrt(&s, &p, &mut ctx).unwrap();
-        assert_eq!(out, BigNum::from_hex_str("7C6D179E19B97BDD").unwrap());
+        // Square the root because OpenSSL randomly returns one of 2E42C or 4FA85
+        sqrt.mod_sqrt(&s, &p, &mut ctx).unwrap();
+        out.mod_sqr(&sqrt, &p, &mut ctx).unwrap();
+        assert!(out == s);
+
+        let s = BigNum::from_hex_str("3").unwrap();
+        let p = BigNum::from_hex_str("5").unwrap();
+        assert!(out.mod_sqrt(&s, &p, &mut ctx).is_err());
     }
 
     #[test]