RFC 8032: Avoid unnecessary doublings in precomputation

2 files changed, 10 insertions, 4 deletions

diff --git a/crypto/src/math/ec/rfc8032/Ed25519.cs b/crypto/src/math/ec/rfc8032/Ed25519.cs

index 2dd9e2f6f..f9ba1ff97 100644
--- a/crypto/src/math/ec/rfc8032/Ed25519.cs
+++ b/crypto/src/math/ec/rfc8032/Ed25519.cs
@@ -670,9 +670,12 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032
 
                     ds[t] = PointCopy(p);
 
-                    for (int s = 1; s < PrecompSpacing; ++s)
+                    if (b + t != PrecompBlocks + PrecompTeeth - 2)
                     {
-                        PointDouble(p);
+                        for (int s = 1; s < PrecompSpacing; ++s)
+                        {
+                            PointDouble(p);
+                        }
                     }
                 }
 
diff --git a/crypto/src/math/ec/rfc8032/Ed448.cs b/crypto/src/math/ec/rfc8032/Ed448.cs

index f12aa0807..a1f0e93b0 100644
--- a/crypto/src/math/ec/rfc8032/Ed448.cs
+++ b/crypto/src/math/ec/rfc8032/Ed448.cs
@@ -622,9 +622,12 @@ namespace Org.BouncyCastle.Math.EC.Rfc8032
 
                     ds[t] = PointCopy(p);
 
-                    for (int s = 1; s < PrecompSpacing; ++s)
+                    if (b + t != PrecompBlocks + PrecompTeeth - 2)
                     {
-                        PointDouble(p);
+                        for (int s = 1; s < PrecompSpacing; ++s)
+                        {
+                            PointDouble(p);
+                        }
                     }
                 }