diff --git a/Aptos.Tests/Aptos.Clients/Aptos.AccountClient.Tests.cs b/Aptos.Tests/Aptos.Clients/Aptos.AccountClient.Tests.cs
index e2f5947..a2f5699 100644
--- a/Aptos.Tests/Aptos.Clients/Aptos.AccountClient.Tests.cs
+++ b/Aptos.Tests/Aptos.Clients/Aptos.AccountClient.Tests.cs
@@ -41,7 +41,7 @@ await client.Account.GetCoinBalance(
         Assert.Null(
             await client.Account.GetCoinBalance(
                 "0x66cb05df2d855fbae92cdb2dfac9a0b29c969a03998fa817735d27391b52b189",
-                "0x123a"
+                "0xc"
             )
         );
     }
diff --git a/Aptos.Tests/Aptos.Core/AccountAddress.Tests.cs b/Aptos.Tests/Aptos.Core/AccountAddress.Tests.cs
index 781cf43..e4d3c0f 100644
--- a/Aptos.Tests/Aptos.Core/AccountAddress.Tests.cs
+++ b/Aptos.Tests/Aptos.Core/AccountAddress.Tests.cs
@@ -30,8 +30,8 @@ public void WhenIConvertTheTypeToAType(string _, string outputType)
         {
             _output = outputType switch
             {
-                "string" => AccountAddress.From(_inputValue),
-                "string long" => AccountAddress.From(_inputValue).ToStringLong(),
+                "string" => AccountAddress.From(_inputValue, 63),
+                "string long" => AccountAddress.From(_inputValue, 63).ToStringLong(),
                 _ => throw new ArgumentException("Invalid type"),
             };
         }
@@ -50,7 +50,7 @@ public void ThenTheResultShouldBeTypeValue(string type, string value)
         switch (type)
         {
             case "address":
-                Assert.Equal(AccountAddress.From(value), _output);
+                Assert.Equal(AccountAddress.From(value, 63), _output);
                 break;
             case "string":
                 Assert.Equal(value.Trim('\"'), _output.ToString());
diff --git a/Aptos.Tests/Aptos.Crypto/MultiKey.Tests.cs b/Aptos.Tests/Aptos.Crypto/MultiKey.Tests.cs
index dd240c1..2ec6439 100644
--- a/Aptos.Tests/Aptos.Crypto/MultiKey.Tests.cs
+++ b/Aptos.Tests/Aptos.Crypto/MultiKey.Tests.cs
@@ -1,7 +1,5 @@
 namespace Aptos.Tests.Crypto;
 
-using Aptos.Indexer.GraphQL;
-using Newtonsoft.Json;
 using Xunit.Gherkin.Quick;
 
 [FeatureFile("../../../../features/multi_key.feature")]
@@ -45,9 +43,10 @@ public void GivenValue(string type, string values)
             var signerTypes = splitValues[1].Split(",");
             var signers = splitValues[2].Split(",");
             List<Account> deserializedSigners = signerTypes
-                .Select<string, Account>(
+                .Select(
                     (type, i) =>
-                        type switch
+                    {
+                        Account account = type switch
                         {
                             "ed25519_ed25519_pk" => new Ed25519Account(
                                 Ed25519PrivateKey.Deserialize(new(signers[i]))
@@ -57,7 +56,11 @@ public void GivenValue(string type, string values)
                             ),
                             "account_keyless" => KeylessAccount.Deserialize(new(signers[i])),
                             _ => throw new ArgumentException("Invalid signer type"),
-                        }
+                        };
+                        if (account is KeylessAccount keylessAccount)
+                            BaseTests.MockKeylessAccount(keylessAccount);
+                        return account;
+                    }
                 )
                 .ToList();
             _inputValue = new MultiKeyAccount(MultiKey.Deserialize(new(key)), deserializedSigners);
diff --git a/Aptos.Tests/Aptos.Tests.csproj b/Aptos.Tests/Aptos.Tests.csproj
index 433af4c..a584acd 100644
--- a/Aptos.Tests/Aptos.Tests.csproj
+++ b/Aptos.Tests/Aptos.Tests.csproj
@@ -6,9 +6,11 @@
     <IsTestProject>true</IsTestProject>
   </PropertyGroup>
 
+
   <ItemGroup>
     <PackageReference Include="coverlet.collector" Version="6.0.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="xunit" Version="2.5.3" />
     <PackageReference Include="Xunit.Gherkin.Quick" Version="4.5.0" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.3" />
diff --git a/Aptos.Tests/BaseTests.cs b/Aptos.Tests/BaseTests.cs
index 25c2c62..3c0d51f 100644
--- a/Aptos.Tests/BaseTests.cs
+++ b/Aptos.Tests/BaseTests.cs
@@ -1,4 +1,6 @@
+using System.Reflection;
 using dotenv.net;
+using Moq;
 
 namespace Aptos.Tests;
 
@@ -30,4 +32,19 @@ public static string[] ParseArray(string input)
         // Split the input string by commas and convert to integers
         return [.. input.Split(',')];
     }
+
+    /// <summary>
+    /// Mock a KeylessAccount to enable signing even if the EphemeralKeyPair is expired.
+    /// </summary>
+    /// <param name="keylessAccount">The keyless account with an expired values.</param>
+    public static void MockKeylessAccount(KeylessAccount keylessAccount)
+    {
+        var field = typeof(KeylessAccount).GetField(
+            "EphemeralKeyPair",
+            BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public
+        );
+        var mock = new Mock<EphemeralKeyPair>(keylessAccount.EphemeralKeyPair);
+        mock.Setup(m => m.IsExpired()).Returns(false);
+        field?.SetValue(keylessAccount, mock.Object);
+    }
 }
diff --git a/Aptos/Aptos.Accounts/EphemeralKeyPair.cs b/Aptos/Aptos.Accounts/EphemeralKeyPair.cs
index 6c6b3a3..253d15f 100644
--- a/Aptos/Aptos.Accounts/EphemeralKeyPair.cs
+++ b/Aptos/Aptos.Accounts/EphemeralKeyPair.cs
@@ -18,7 +18,7 @@ public class EphemeralKeyPair : Serializable
     /// The private key is used to sign transactions. This private key is not tied to any account on the chain as it is
     /// ephemeral (not permanent) in nature.
     /// </summary>
-    private PrivateKey _privateKey;
+    private readonly PrivateKey _privateKey;
 
     /// <summary>
     /// A public key used to verify transactions. This public key is not tied to any account on the chain as it is
@@ -39,6 +39,9 @@ public class EphemeralKeyPair : Serializable
     /// </summary>
     public readonly string Nonce;
 
+    public EphemeralKeyPair(EphemeralKeyPair other)
+        : this(other._privateKey, other.ExpiryTimestamp, other.Blinder) { }
+
     public EphemeralKeyPair(
         PrivateKey privateKey,
         ulong? expiryTimestamp = null,
@@ -64,7 +67,7 @@ public EphemeralKeyPair(
         Nonce = Hash.PoseidonHash(fields).ToString();
     }
 
-    public bool IsExpired() => (ulong)DateTime.Now.ToUnixTimestamp() > ExpiryTimestamp;
+    public virtual bool IsExpired() => (ulong)DateTime.Now.ToUnixTimestamp() > ExpiryTimestamp;
 
     public EphemeralSignature Sign(byte[] data)
     {
diff --git a/Aptos/Aptos.Accounts/KeylessAccount.cs b/Aptos/Aptos.Accounts/KeylessAccount.cs
index d0f5ee3..bef044f 100644
--- a/Aptos/Aptos.Accounts/KeylessAccount.cs
+++ b/Aptos/Aptos.Accounts/KeylessAccount.cs
@@ -84,8 +84,6 @@ public override Signature Sign(AnyRawTransaction transaction)
 
     public override Signature Sign(byte[] message)
     {
-        if (EphemeralKeyPair.IsExpired())
-            throw new Exception("Ephemeral keypair has expired");
         var token = new JsonWebToken(Jwt);
         return new KeylessSignature(
             ephemeralCertificate: new EphemeralCertificate(
diff --git a/Aptos/Aptos.Core/AccountAddress.cs b/Aptos/Aptos.Core/AccountAddress.cs
index 4225868..367fb98 100644
--- a/Aptos/Aptos.Core/AccountAddress.cs
+++ b/Aptos/Aptos.Core/AccountAddress.cs
@@ -95,7 +95,7 @@ public override void SerializeForScriptFunction(Serializer s)
 
     public static AccountAddress Deserialize(Deserializer d) => new(d.FixedBytes(LENGTH));
 
-    public static AccountAddress FromString(string str)
+    public static AccountAddress FromString(string str, int maxMissingChars = 4)
     {
         string parsedInput = str;
 
@@ -114,10 +114,16 @@ public static AccountAddress FromString(string str)
                 AccountAddressInvalidReason.TooLong
             );
 
-        byte[] addressBytes;
+        if (maxMissingChars > 63 || maxMissingChars < 0)
+            throw new AccountAddressParsingException(
+                $"maxMissingChars must be between or equal to 0 and 63. Received {maxMissingChars}",
+                AccountAddressInvalidReason.InvalidPaddingStrictness
+            );
+
+        AccountAddress address;
         try
         {
-            addressBytes = Utilities.HexStringToBytes(parsedInput.PadLeft(64, '0'));
+            address = new AccountAddress(Utilities.HexStringToBytes(parsedInput.PadLeft(64, '0')));
         }
         catch
         {
@@ -127,7 +133,18 @@ public static AccountAddress FromString(string str)
             );
         }
 
-        return new AccountAddress(addressBytes);
+        if (parsedInput.Length < 64 - maxMissingChars)
+        {
+            if (!address.IsSpecial())
+            {
+                throw new AccountAddressParsingException(
+                    $"Hex string is too short, must be between {64 - maxMissingChars} and 64 chars, excluding the leading 0x. You may need to fix the address by pading it with 0s before passing it to `fromString` (e.g. <addressString>.PadLeft(64, '0')). Received {str}",
+                    AccountAddressInvalidReason.TooShort
+                );
+            }
+        }
+
+        return address;
     }
 
     public static AccountAddress FromStringStrict(string str)
@@ -161,7 +178,8 @@ public static AccountAddress FromStringStrict(string str)
         return address;
     }
 
-    public static AccountAddress From(string str) => FromString(str);
+    public static AccountAddress From(string str, int maxMissingChars = 4) =>
+        FromString(str, maxMissingChars);
 
     public static AccountAddress From(byte[] bytes) => new(bytes);
 
diff --git a/Aptos/Aptos.Crypto/MultiKey.cs b/Aptos/Aptos.Crypto/MultiKey.cs
index de67f3e..9bf2916 100644
--- a/Aptos/Aptos.Crypto/MultiKey.cs
+++ b/Aptos/Aptos.Crypto/MultiKey.cs
@@ -40,6 +40,20 @@ public static int BitCount(byte b)
         n = (n + (n >> 4)) & 0x0F0F0F0Fu;
         return (int)((n * 0x01010101u) >> 24);
     }
+
+    public static MultiKeySignature GetSimulationSignature(MultiKey multiKey) =>
+        GetSimulationSignature(multiKey.PublicKeys.Count);
+
+    public static MultiKeySignature GetSimulationSignature(int keysCount)
+    {
+        return new MultiKeySignature(
+            signatures: Enumerable
+                .Range(0, keysCount)
+                .Select(i => (PublicKeySignature)new Ed25519Signature(new byte[64]))
+                .ToList(),
+            bitmap: CreateBitmap(Enumerable.Range(0, keysCount).Select(i => i).ToArray())
+        );
+    }
 }
 
 public partial class MultiKey : Serializable, IVerifyingKey
diff --git a/Aptos/Aptos.Exceptions/Common.cs b/Aptos/Aptos.Exceptions/Common.cs
index b1e2e72..53b0bb5 100644
--- a/Aptos/Aptos.Exceptions/Common.cs
+++ b/Aptos/Aptos.Exceptions/Common.cs
@@ -21,6 +21,7 @@ public enum AccountAddressInvalidReason
         LeadingZeroXRequired,
         LongFormRequiredUnlessSpecial,
         InvalidPaddingZeroes,
+        InvalidPaddingStrictness,
     }
 
     public class AccountAddressParsingException(string message, AccountAddressInvalidReason reason)
diff --git a/Aptos/Aptos.Transactions/SimulateTransactionData.cs b/Aptos/Aptos.Transactions/SimulateTransactionData.cs
index 4637d7a..cd29e29 100644
--- a/Aptos/Aptos.Transactions/SimulateTransactionData.cs
+++ b/Aptos/Aptos.Transactions/SimulateTransactionData.cs
@@ -1,3 +1,5 @@
+using OneOf;
+
 namespace Aptos;
 
 public class SimulateTransactionOptions(
@@ -13,15 +15,16 @@ public class SimulateTransactionOptions(
 
 public class SimulateTransactionData(
     AnyRawTransaction transaction,
-    PublicKey signerPublicKey,
-    PublicKey[]? secondarySignersPublicKeys = null,
-    PublicKey? feePayerPublicKey = null,
+    OneOf<PublicKey, IVerifyingKey> signerPublicKey,
+    OneOf<PublicKey, IVerifyingKey>[]? secondarySignersPublicKeys = null,
+    OneOf<PublicKey, IVerifyingKey>? feePayerPublicKey = null,
     SimulateTransactionOptions? options = null
 )
 {
     public AnyRawTransaction Transaction = transaction;
-    public PublicKey SignerPublicKey = signerPublicKey;
-    public PublicKey[]? SecondarySignersPublicKeys = secondarySignersPublicKeys;
-    public PublicKey? FeePayerPublicKey = feePayerPublicKey;
+    public OneOf<PublicKey, IVerifyingKey> SignerPublicKey = signerPublicKey;
+    public OneOf<PublicKey, IVerifyingKey>[]? SecondarySignersPublicKeys =
+        secondarySignersPublicKeys;
+    public OneOf<PublicKey, IVerifyingKey>? FeePayerPublicKey = feePayerPublicKey;
     public SimulateTransactionOptions? Options = options;
 }
diff --git a/Aptos/Aptos.Transactions/TransactionBuilder.cs b/Aptos/Aptos.Transactions/TransactionBuilder.cs
index 2bcbc64..953ffe2 100644
--- a/Aptos/Aptos.Transactions/TransactionBuilder.cs
+++ b/Aptos/Aptos.Transactions/TransactionBuilder.cs
@@ -1,38 +1,54 @@
 namespace Aptos;
 
 using Aptos.Core;
-using Aptos.Exceptions;
+using OneOf;
 
 public static class TransactionBuilder
 {
     #region GetAuthenticator
 
-    public static AccountAuthenticator GetAuthenticatorForSimulation(PublicKey publicKey)
+    public static AccountAuthenticator GetAuthenticatorForSimulation(
+        OneOf<PublicKey, IVerifyingKey> publicOrVerifyingKey
+    )
     {
         Ed25519Signature invalidSignature = new(new byte[64]);
 
-        if (publicKey is Ed25519PublicKey ed25519PublicKey)
-        {
-            return new AccountAuthenticatorEd25519(ed25519PublicKey, invalidSignature);
-        }
-
-        if (publicKey is KeylessPublicKey keylessPublicKey)
-        {
-            return new AccountAuthenticatorSingleKey(
-                keylessPublicKey,
-                Keyless.GetSimulationSignature()
-            );
-        }
+        return publicOrVerifyingKey.Match<AccountAuthenticator>(
+            publicKey =>
+            {
+                if (publicKey is Ed25519PublicKey ed25519PublicKey)
+                    return new AccountAuthenticatorEd25519(ed25519PublicKey, invalidSignature);
+
+                if (publicKey is KeylessPublicKey keylessPublicKey)
+                    return new AccountAuthenticatorSingleKey(
+                        keylessPublicKey,
+                        Keyless.GetSimulationSignature()
+                    );
+                if (publicKey is FederatedKeylessPublicKey federatedKeylessPublicKey)
+                    return new AccountAuthenticatorSingleKey(
+                      federatedKeylessPublicKey,
+                      Keyless.GetSimulationSignature()
+                    );
+
+                return new AccountAuthenticatorSingleKey(publicKey, invalidSignature);
+            },
+            verifyingKey =>
+            {
+                if (verifyingKey is SingleKey singleKey)
+                    return new AccountAuthenticatorSingleKey(singleKey.PublicKey, invalidSignature);
 
-        if (publicKey is FederatedKeylessPublicKey federatedKeylessPublicKey)
-        {
-            return new AccountAuthenticatorSingleKey(
-                federatedKeylessPublicKey,
-                Keyless.GetSimulationSignature()
-            );
-        }
+                if (verifyingKey is MultiKey multiKey)
+                    return new AccountAuthenticatorMultiKey(
+                        multiKey,
+                        MultiKey.GetSimulationSignature(multiKey)
+                    );
 
         return new AccountAuthenticatorSingleKey(publicKey, invalidSignature);
+                throw new ArgumentException(
+                    $"{verifyingKey.GetType().Name} is not supported for simulation."
+                );
+            }
+        );
     }
 
     #endregion
@@ -124,7 +140,7 @@ SimulateTransactionData data
                 ?? [];
 
             AccountAuthenticator feePayerAuthenticator = GetAuthenticatorForSimulation(
-                data.FeePayerPublicKey
+                (OneOf<PublicKey, IVerifyingKey>)data.FeePayerPublicKey
             );
 
             TransactionAuthenticatorFeePayer feePayerTransactionAuthenticator =
diff --git a/Aptos/Aptos.csproj b/Aptos/Aptos.csproj
index ae9083a..448375d 100644
--- a/Aptos/Aptos.csproj
+++ b/Aptos/Aptos.csproj
@@ -18,6 +18,7 @@
 
   <ItemGroup>
     <PackageReference Include="BouncyCastle.Cryptography" Version="2.4.0" />
+    <PackageReference Include="OneOf" Version="3.0.271" />
     <PackageReference Include="StrawberryShake.Transport.Http" Version="13.9.11" />
     <PackageReference Include="StrawberryShake" Version="13.9.11" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
diff --git a/Directory.Build.props b/Directory.Build.props
index 535b5c9..9bcaab2 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -2,7 +2,7 @@
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <!-- There should only be one <DefaultVersion> in the file. If moved, it should be updated in the GitHub Actions workflow. -->
-    <DefaultVersion>0.0.9</DefaultVersion>
+    <DefaultVersion>0.0.11</DefaultVersion>
     <DefaultTargetFrameworks>net8.0;net7.0;net6.0;netstandard2.1</DefaultTargetFrameworks>
     <DefaultTestingFrameworks>net8.0</DefaultTestingFrameworks>
   </PropertyGroup>
diff --git a/index.md b/index.md
index c7f849e..18685c3 100644
--- a/index.md
+++ b/index.md
@@ -16,7 +16,7 @@ dotnet add package Aptos
 
 ## Explore
 
-- [Aptos](/docs/Aptos.html): The main namespace for interacting with the Aptos blockchain.
-- [Aptos.Core](/docs/Aptos.Core.html): Core utilities for the SDK.
-- [Aptos.Schemes](/docs/Aptos.Schemes.html): All authentication schemes supported in the SDK.
-- [Aptos.Exceptions](/docs/Aptos.Exceptions.html): All data types for exceptions thrown by the SDK.
\ No newline at end of file
+- [Aptos](/aptos-dotnet-sdk/docs/Aptos.html): The main namespace for interacting with the Aptos blockchain.
+- [Aptos.Core](/aptos-dotnet-sdk/docs/Aptos.Core.html): Core utilities for the SDK.
+- [Aptos.Schemes](/aptos-dotnet-sdk/docs/Aptos.Schemes.html): All authentication schemes supported in the SDK.
+- [Aptos.Exceptions](/aptos-dotnet-sdk/docs/Aptos.Exceptions.html): All data types for exceptions thrown by the SDK.
\ No newline at end of file