diff --git a/src/Neo/Cryptography/Base58.cs b/src/Neo/Cryptography/Base58.cs index a2f562b06b..5f2fa3cc34 100644 --- a/src/Neo/Cryptography/Base58.cs +++ b/src/Neo/Cryptography/Base58.cs @@ -12,6 +12,7 @@ using System; using System.Linq; using System.Numerics; +using System.Runtime.CompilerServices; using System.Text; namespace Neo.Cryptography @@ -25,6 +26,21 @@ public static class Base58 /// Represents the alphabet of the base-58 encoder. /// public const string Alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"; + private const char ZeroChar = '1'; + private static readonly BigInteger s_alphabetLength = Alphabet.Length; + + #pragma warning disable format + private static readonly sbyte[] s_decodeMap = + [ + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, + -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, + 7, 8, -1, -1, -1, -1, -1, -1, -1, 9, 10, 11, 12, 13, 14, 15, 16, -1, 17, + 18, 19, 20, 21, -1, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, -1, -1, + -1, -1, -1, -1, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, -1, 44, 45, + 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57 + ]; + #pragma warning restore format /// /// Converts the specified , which encodes binary data as base-58 digits, to an equivalent byte array. The encoded contains the checksum of the binary data. @@ -71,21 +87,30 @@ public static byte[] Decode(string input) { // Decode Base58 string to BigInteger var bi = BigInteger.Zero; - for (int i = 0; i < input.Length; i++) + sbyte digit; + for (var i = 0; i < input.Length; i++) { - int digit = Alphabet.IndexOf(input[i]); - if (digit < 0) + if (input[i] >= 123) + throw new FormatException($"Invalid Base58 character '{input[i]}' at position {i}"); + digit = s_decodeMap[input[i]]; + if (digit == -1) throw new FormatException($"Invalid Base58 character '{input[i]}' at position {i}"); - bi = bi * Alphabet.Length + digit; + bi = bi * s_alphabetLength + digit; } // Encode BigInteger to byte[] // Leading zero bytes get encoded as leading `1` characters - int leadingZeroCount = input.TakeWhile(c => c == Alphabet[0]).Count(); - var leadingZeros = new byte[leadingZeroCount]; - if (bi.IsZero) return leadingZeros; - var bytesWithoutLeadingZeros = bi.ToByteArray(isUnsigned: true, isBigEndian: true); - return [.. leadingZeros, .. bytesWithoutLeadingZeros]; + + var leadingZeroCount = LeadingBase58Zeros(input); + if (bi.IsZero) + { + return new byte[leadingZeroCount]; + } + + var result = new byte[leadingZeroCount + bi.GetByteCount(true)]; + + _ = bi.TryWriteBytes(result.AsSpan(leadingZeroCount), out _, true, true); + return result; } /// @@ -99,20 +124,35 @@ public static string Encode(ReadOnlySpan input) BigInteger value = new(input, isUnsigned: true, isBigEndian: true); // Encode BigInteger to Base58 string - var sb = new StringBuilder(); + var sb = new StringBuilder(input.Length * 138 / 100 + 5); while (value > 0) { - value = BigInteger.DivRem(value, Alphabet.Length, out var remainder); - sb.Insert(0, Alphabet[(int)remainder]); + value = BigInteger.DivRem(value, s_alphabetLength, out var remainder); + sb.Append(Alphabet[(int)remainder]); } // Append `1` for each leading 0 byte for (int i = 0; i < input.Length && input[i] == 0; i++) { - sb.Insert(0, Alphabet[0]); + sb.Append(ZeroChar); } - return sb.ToString(); + + Span copy = stackalloc char[sb.Length]; + sb.CopyTo(0, copy, sb.Length); + copy.Reverse(); + + return copy.ToString(); + } + + [MethodImpl(MethodImplOptions.AggressiveInlining)] + private static int LeadingBase58Zeros(string collection) + { + var i = 0; + var len = collection.Length; + for (; i < len && collection[i] == ZeroChar; i++) { } + + return i; } } }