73 lines
2.0 KiB
C#
73 lines
2.0 KiB
C#
using System;
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namespace Bit.Core.Utilities
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{
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// ref: https://github.com/aspnet/Identity/blob/dev/src/Microsoft.Extensions.Identity.Core/Base32.cs
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// with some modifications for cleaning input
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public static class Base32
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{
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private static readonly string _base32Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
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public static byte[] FromBase32(string input)
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{
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if (input == null)
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{
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throw new ArgumentNullException(nameof(input));
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}
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input = input.ToUpperInvariant();
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var cleanedInput = string.Empty;
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foreach (var c in input)
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{
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if (_base32Chars.IndexOf(c) < 0)
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{
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continue;
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}
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cleanedInput += c;
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}
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input = cleanedInput;
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if (input.Length == 0)
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{
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return new byte[0];
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}
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var output = new byte[input.Length * 5 / 8];
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var bitIndex = 0;
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var inputIndex = 0;
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var outputBits = 0;
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var outputIndex = 0;
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while (outputIndex < output.Length)
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{
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var byteIndex = _base32Chars.IndexOf(input[inputIndex]);
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if (byteIndex < 0)
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{
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throw new FormatException();
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}
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var bits = Math.Min(5 - bitIndex, 8 - outputBits);
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output[outputIndex] <<= bits;
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output[outputIndex] |= (byte)(byteIndex >> (5 - (bitIndex + bits)));
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bitIndex += bits;
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if (bitIndex >= 5)
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{
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inputIndex++;
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bitIndex = 0;
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}
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outputBits += bits;
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if (outputBits >= 8)
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{
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outputIndex++;
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outputBits = 0;
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}
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}
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return output;
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}
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}
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}
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