Merge pull request #156 from IOTA-NET/152-allow-bech32-encoding-and-decoding-to-ed22519

Bech32 encoding decoding

Author: wireless90

csharp/IotaWalletNet/IotaWalletNet.Domain/Common/Extensions/StringExtensions.cs

@@ -1,4 +1,9 @@
-using Blake2Fast;
+using Bech32;
+using Blake2Fast;
+using IotaWalletNet.Domain.Common.Models.Address;
+using IotaWalletNet.Domain.Common.Models.Coin;
+using IotaWalletNet.Domain.Common.Models.Network;
+using System.Buffers.Text;
 using System.Text;
 
 namespace IotaWalletNet.Domain.Common.Extensions
@@ -42,5 +47,35 @@ public static string ComputeBlake2bHash(this string hexEncoded)
 
             return "0x" + Convert.ToHexString(hash);
         }
+        
+        public static string EncodeEd25519HashIntoBech32(this string blake2bHashOfEd25519, NetworkType networkType, TypeOfCoin typeOfCoin)
+        {
+            blake2bHashOfEd25519 = blake2bHashOfEd25519.Trim().ToLower();
+            if (blake2bHashOfEd25519.StartsWith("0x"))
+                blake2bHashOfEd25519 = blake2bHashOfEd25519.Substring(2); // remove the 0x of a hexstring eg 0x1337
+
+            string hrp = HumanReadablePart.GetHumanReadablePart(networkType, typeOfCoin);
+            const string ED25519_TYPE = "00";
+            blake2bHashOfEd25519 = ED25519_TYPE + blake2bHashOfEd25519;
+
+            string bech32 = Bech32Engine.Encode(hrp, Convert.FromHexString(blake2bHashOfEd25519));
+
+            const string HRP_CONSTANT = "1";
+
+            return $"{hrp}{HRP_CONSTANT}{bech32}";
+        }
+
+        public static string DecodeBech32IntoEd25519Hash(this string bech32, NetworkType networkType, TypeOfCoin typeOfCoin)
+        {
+            bech32 = bech32.Trim().ToLower();
+
+            string hrp = HumanReadablePart.GetHumanReadablePart(networkType, typeOfCoin);
+
+            string bech32OfInterest = bech32.Substring(4); //eg remove iota1 or smr1 or atoi1 or rms1
+
+            byte[] decoded = Bech32Engine.Decode(bech32OfInterest, hrp);
+            
+            return "0x" + Convert.ToHexString(decoded);
+        }
     }
 }

csharp/IotaWalletNet/IotaWalletNet.Domain/Common/Models/Address/HumanReadablePart.cs

@@ -0,0 +1,48 @@
+using IotaWalletNet.Domain.Common.Models.Coin;
+using IotaWalletNet.Domain.Common.Models.Network;
+
+namespace IotaWalletNet.Domain.Common.Models.Address
+{
+    /// <summary>
+    /// 
+    ///    Bech32 for human-readable encoding
+    ///     The human-readable encoding of the address is Bech32(as described in BIP-0173). A Bech32 string is at most 90 characters long and consists of:
+
+    ///     The human-readable part(HRP), which conveys the IOTA protocol and distinguishes between Mainnet(the IOTA token) and Testnet(testing version):
+    ///     iota is the human-readable part for Mainnet addresses
+    ///     atoi is the human-readable part for Testnet addresses
+    ///     The separator, which is always 1.
+    ///     The data part, which consists of the Base32 encoded serialized address and the 6-character checksum.
+    /// </summary>
+    public static class HumanReadablePart
+    {
+        public enum HRP
+        {
+            iota,
+            atoi,
+            smr,
+            rms
+        }
+
+        private static IReadOnlyDictionary<TypeOfCoin, string> MainnetToHrp = new Dictionary<TypeOfCoin, string>()
+        {
+            { TypeOfCoin.Iota, HRP.iota.ToString() },
+            { TypeOfCoin.Shimmer, HRP.smr.ToString() },
+
+        };
+        private static IReadOnlyDictionary<TypeOfCoin, string> TestnetToHrp = new Dictionary<TypeOfCoin, string>()
+        {
+            { TypeOfCoin.Iota, HRP.atoi.ToString() },
+            { TypeOfCoin.Shimmer, HRP.rms.ToString() },
+
+        };
+
+        public static string GetHumanReadablePart(NetworkType networkType, TypeOfCoin typeOfCoin)
+        {
+            if (networkType == NetworkType.Mainnet)
+                return MainnetToHrp[typeOfCoin];
+            else
+                return TestnetToHrp[typeOfCoin];
+        }
+    }
+}