Add VRF random number to neo

src/neo/NeoSystem.cs

@@ -134,6 +134,7 @@ public NeoSystem(ProtocolSettings settings, string storageEngine = null, string
                 MerkleRoot = UInt256.Zero,
                 Timestamp = (new DateTime(2016, 7, 15, 15, 8, 21, DateTimeKind.Utc)).ToTimestampMS(),
                 Index = 0,
+                Nonce = 2083236893, // nonce from  the Bitcoin genesis block.
                 PrimaryIndex = 0,
                 NextConsensus = Contract.GetBFTAddress(settings.StandbyValidators),
                 Witness = new Witness

src/neo/Network/P2P/Payloads/Block.cs

@@ -51,6 +51,11 @@ public sealed class Block : IEquatable<Block>, IInventory
         /// </summary>
         public uint Index => Header.Index;
 
+        /// <summary>
+        /// The random number of the block from VRF.
+        /// </summary>
+        public uint Nonce => Header.Nonce;
+
         /// <summary>
         /// The primary index of the consensus node that generated this block.
         /// </summary>

src/neo/Network/P2P/Payloads/Header.cs

@@ -20,9 +20,11 @@ public sealed class Header : IEquatable<Header>, IVerifiable
         private UInt256 merkleRoot;
         private ulong timestamp;
         private uint index;
+        private uint nonce;
         private byte primaryIndex;
         private UInt160 nextConsensus;
 
+
         /// <summary>
         /// The witness of the block.
         /// </summary>
@@ -73,6 +75,15 @@ public uint Index
             set { index = value; _hash = null; }
         }
 
+        /// <summary>
+        /// The last four bytes of random number generated from VRF
+        /// </summary>
+        public uint Nonce
+        {
+            get => nonce;
+            set { nonce = value; _hash = null; }
+        }
+
         /// <summary>
         /// The primary index of the consensus node that generated this block.
         /// </summary>
@@ -110,6 +121,7 @@ public UInt256 Hash
             UInt256.Length +    // MerkleRoot
             sizeof(ulong) +     // Timestamp
             sizeof(uint) +      // Index
+            sizeof(uint) +      // Nonce
             sizeof(byte) +      // PrimaryIndex
             UInt160.Length +    // NextConsensus
             1 + Witness.Size;   // Witness   
@@ -144,6 +156,7 @@ void IVerifiable.DeserializeUnsigned(BinaryReader reader)
             merkleRoot = reader.ReadSerializable<UInt256>();
             timestamp = reader.ReadUInt64();
             index = reader.ReadUInt32();
+            nonce = reader.ReadUInt32();
             primaryIndex = reader.ReadByte();
             nextConsensus = reader.ReadSerializable<UInt160>();
         }
@@ -186,6 +199,7 @@ void IVerifiable.SerializeUnsigned(BinaryWriter writer)
             writer.Write(merkleRoot);
             writer.Write(timestamp);
             writer.Write(index);
+            writer.Write(nonce);
             writer.Write(primaryIndex);
             writer.Write(nextConsensus);
         }
@@ -205,6 +219,7 @@ public JObject ToJson(ProtocolSettings settings)
             json["merkleroot"] = merkleRoot.ToString();
             json["time"] = timestamp;
             json["index"] = index;
+            json["nonce"] = nonce;
             json["primary"] = primaryIndex;
             json["nextconsensus"] = nextConsensus.ToAddress(settings.AddressVersion);
             json["witnesses"] = new JArray(Witness.ToJson());

src/neo/SmartContract/ApplicationEngine.Runtime.cs

@@ -77,6 +77,13 @@ partial class ApplicationEngine
         /// </summary>
         public static readonly InteropDescriptor System_Runtime_GetInvocationCounter = Register("System.Runtime.GetInvocationCounter", nameof(GetInvocationCounter), 1 << 4, CallFlags.None);
 
+        /// <summary>
+        /// The <see cref="InteropDescriptor"/> of System.Runtime.GetRandom.
+        /// Gets the random number generated form the VRF.
+        /// </summary>
+        public static readonly InteropDescriptor System_Runtime_GetRandom = Register("System.Runtime.GetRandom", nameof(GetRandom), 1 << 4, CallFlags.None);
+
+
         /// <summary>
         /// The <see cref="InteropDescriptor"/> of System.Runtime.Log.
         /// Writes a log.
@@ -228,6 +235,17 @@ protected internal int GetInvocationCounter()
             return counter;
         }
 
+        /// <summary>
+        /// The implementation of System.Runtime.GetRandom.
+        /// Gets the random number genrated form the VRF
+        /// Primary geterates this random number with `prevHash`, the hash of the previous (validators.Length/3 + 1) block
+        /// </summary>
+        /// <returns>The last four bytes of the random number.</returns>
+        protected internal uint GetRandom()
+        {
+            return PersistingBlock.Header.Nonce;
+        }
+
         /// <summary>
         /// The implementation of System.Runtime.Log.
         /// Writes a log.

src/neo/SmartContract/Native/StdLib.cs

@@ -142,6 +142,28 @@ public static byte[] Base58Decode([MaxLength(MaxInputLength)] string s)
             return Base58.Decode(s);
         }
 
+        /// <summary>
+        /// Converts a byte array to its equivalent <see cref="string"/> representation that is encoded with base-58 digits. The encoded <see cref="string"/> contains the checksum of the binary data.
+        /// </summary>
+        /// <param name="data">The byte array to be encoded.</param>
+        /// <returns>The encoded <see cref="string"/>.</returns>
+        [ContractMethod(CpuFee = 1 << 16)]
+        public static string Base58CheckEncode([MaxLength(MaxInputLength)] byte[] data)
+        {
+            return Base58.Base58CheckEncode(data);
+        }
+
+        /// <summary>
+        /// Converts the specified <see cref="string"/>, which encodes binary data as base-58 digits, to an equivalent byte array. The encoded <see cref="string"/> contains the checksum of the binary data.
+        /// </summary>
+        /// <param name="s">The base58 <see cref="string"/>.</param>
+        /// <returns>The decoded byte array.</returns>
+        [ContractMethod(CpuFee = 1 << 16)]
+        public static byte[] Base58CheckDecode([MaxLength(MaxInputLength)] string s)
+        {
+            return Base58.Base58CheckDecode(s);
+        }
+
         [ContractMethod(CpuFee = 1 << 5)]
         private static int MemoryCompare([MaxLength(MaxInputLength)] byte[] str1, [MaxLength(MaxInputLength)] byte[] str2)
         {