Reject splitting negative amounts

Author: NicolasDorier

NBitcoin.Tests/Secp256k1Tests.cs

@@ -4557,18 +4557,6 @@ public void schnorr_adaptor_tests()
 			}
 		}
 
-		[Fact]
-		[Trait("UnitTest", "UnitTest")]
-		public void bip340_rejects_non_32_byte_messages()
-		{
-			var key = ECPrivKey.Create(new byte[32] { 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 });
-			var message = new byte[32];
-			var signature = key.SignBIP340(message, new byte[32]);
-
-			Assert.True(key.CreateXOnlyPubKey().SigVerifyBIP340(signature, message));
-			Assert.False(key.CreateXOnlyPubKey().SigVerifyBIP340(signature, new byte[33]));
-		}
-
 		[Fact]
 		[Trait("UnitTest", "UnitTest")]
 		public void musig_key_sort_vectors()

NBitcoin.Tests/util_tests.cs

@@ -547,18 +547,14 @@ public void CanSplitMoney()
 			CanSplitMoneyCore(Money.Satoshis(1234), 2);
 			CanSplitMoneyCore(Money.Satoshis(1234), 10);
 			CanSplitMoneyCore(Money.Satoshis(1), 3);
-			CanSplitMoneyCore(Money.Satoshis(-1234), 3);
-			CanSplitMoneyCore(Money.Satoshis(-1), 3);
+			Assert.Throws<InvalidOperationException>(() => Money.Satoshis(-1).Split(3).ToArray());
 			Assert.Throws<ArgumentOutOfRangeException>(() => CanSplitMoneyCore(Money.Satoshis(1000), 0));
 			CanSplitMoneyCore(Money.Satoshis(0), 10);
 
 			var result = Money.Satoshis(20).Split(3).ToArray();
 			Assert.True(result[0].Satoshi == 7);
 			Assert.True(result[1].Satoshi == 7);
 			Assert.True(result[2].Satoshi == 6);
-
-			result = Money.Satoshis(-20).Split(3).ToArray();
-			Assert.Equal(new long[] { -7, -7, -6 }, result.Select(m => m.Satoshi));
 		}
 
 		private void CanSplitMoneyCore(Money money, int parts)
@@ -594,8 +590,7 @@ public void CanSplitAssetMoney()
 			CanSplitAssetMoneyCore(gold, 1234, 2);
 			CanSplitAssetMoneyCore(gold, 1234, 10);
 			CanSplitAssetMoneyCore(gold, 1, 3);
-			CanSplitAssetMoneyCore(gold, -1234, 3);
-			CanSplitAssetMoneyCore(gold, -1, 3);
+			Assert.Throws<InvalidOperationException>(() => new AssetMoney(gold, -1).Split(3).ToArray());
 			Assert.Throws<ArgumentOutOfRangeException>(() => CanSplitAssetMoneyCore(gold, 1000, 0));
 			CanSplitAssetMoneyCore(gold, 0, 10);
 
@@ -604,9 +599,6 @@ public void CanSplitAssetMoney()
 			Assert.True(result[1].Quantity == 7);
 			Assert.True(result[2].Quantity == 6);
 			Assert.True(result[0].Id == gold);
-
-			result = new AssetMoney(gold, -20).Split(3).ToArray();
-			Assert.Equal(new long[] { -7, -7, -6 }, result.Select(m => m.Quantity));
 		}
 
 		private void CanSplitAssetMoneyCore(AssetId asset, long amount, int parts)

NBitcoin/Money.cs

@@ -417,14 +417,15 @@ public IEnumerable<Money> Split(int parts)
 		{
 			if (parts <= 0)
 				throw new ArgumentOutOfRangeException(nameof(parts), "Parts should be more than 0");
+			if (_Satoshis < 0)
+				throw new InvalidOperationException("Cannot split a negative amount");
 			long remain;
 			long result = DivRem(_Satoshis, parts, out remain);
 
 			for (int i = 0; i < parts; i++)
 			{
-				var remainder = Math.Sign(remain);
-				yield return Money.Satoshis(result + remainder);
-				remain -= remainder;
+				yield return Money.Satoshis(result + (remain > 0 ? 1 : 0));
+				remain--;
 			}
 		}
 

NBitcoin/OpenAsset/AssetMoney.cs

@@ -141,14 +141,15 @@ public IEnumerable<AssetMoney> Split(int parts)
 		{
 			if (parts <= 0)
 				throw new ArgumentOutOfRangeException("Parts should be more than 0", "parts");
+			if (_Quantity < 0)
+				throw new InvalidOperationException("Cannot split a negative amount");
 			long remain;
 			long result = DivRem(_Quantity, parts, out remain);
 
 			for (int i = 0; i < parts; i++)
 			{
-				var remainder = Math.Sign(remain);
-				yield return new AssetMoney(_Id, result + remainder);
-				remain -= remainder;
+				yield return new AssetMoney(_Id, result + (remain > 0 ? 1 : 0));
+				remain--;
 			}
 		}
 

NBitcoin/Secp256k1/ECXOnlyPubKey.cs

@@ -85,7 +85,7 @@ public bool SigVerifyBIP340(SecpSchnorrSignature signature, ReadOnlySpan<byte> m
 		{
 			if (signature is null)
 				return false;
-			if (msg32.Length != 32)
+			if (msg32.Length < 32)
 				return false;
 			Span<byte> buf = stackalloc byte[32];
 			SHA256 sha = new SHA256();
@@ -95,7 +95,7 @@ public bool SigVerifyBIP340(SecpSchnorrSignature signature, ReadOnlySpan<byte> m
 			sha.Write(buf);
 			Q.x.WriteToSpan(buf);
 			sha.Write(buf);
-			sha.Write(msg32);
+			sha.Write(msg32.Slice(0, 32));
 			sha.GetHash(buf);
 			var e = new Scalar(buf, out _);