Base32解码
我有一个base32string，我需要转换为一个字节数组。 而且我在.net框架中find一个转换方法时遇到了问题。 我可以findbase64的方法，但不是base32。
Convert.FromBase64String – 类似于base32的东西将是完美的。
在框架中是否有这样的方法，还是我必须推出自己的？
在这里find这个.NET的FromBase32String实现。
编辑：上面的链接已经死了; 你可以在archive.orgfind一个存档的副本
实际的代码如下：
using System; using System.Text; public sealed class Base32 { // the valid chars for the encoding private static string ValidChars = "QAZ2WSX3" + "EDC4RFV5" + "TGB6YHN7" + "UJM8K9LP"; /// <summary> /// Converts an array of bytes to a Base32-k string. /// </summary> public static string ToBase32String(byte[] bytes) { StringBuilder sb = new StringBuilder(); // holds the base32 chars byte index; int hi = 5; int currentByte = 0; while (currentByte < bytes.Length) { // do we need to use the next byte? if (hi > 8) { // get the last piece from the current byte, shift it to the right // and increment the byte counter index = (byte)(bytes[currentByte++] >> (hi - 5)); if (currentByte != bytes.Length) { // if we are not at the end, get the first piece from // the next byte, clear it and shift it to the left index = (byte)(((byte)(bytes[currentByte] << (16 - hi)) >> 3) | index); } hi -= 3; } else if(hi == 8) { index = (byte)(bytes[currentByte++] >> 3); hi -= 3; } else { // simply get the stuff from the current byte index = (byte)((byte)(bytes[currentByte] << (8 - hi)) >> 3); hi += 5; } sb.Append(ValidChars[index]); } return sb.ToString(); } /// <summary> /// Converts a Base32-k string into an array of bytes. /// </summary> /// <exception cref="System.ArgumentException"> /// Input string <paramref name="s">s</paramref> contains invalid Base32-k characters. /// </exception> public static byte[] FromBase32String(string str) { int numBytes = str.Length * 5 / 8; byte[] bytes = new Byte[numBytes]; // all UPPERCASE chars str = str.ToUpper(); int bit_buffer; int currentCharIndex; int bits_in_buffer; if (str.Length < 3) { bytes[0] = (byte)(ValidChars.IndexOf(str[0]) | ValidChars.IndexOf(str[1]) << 5); return bytes; } bit_buffer = (ValidChars.IndexOf(str[0]) | ValidChars.IndexOf(str[1]) << 5); bits_in_buffer = 10; currentCharIndex = 2; for (int i = 0; i < bytes.Length; i++) { bytes[i] = (byte)bit_buffer; bit_buffer >>= 8; bits_in_buffer -= 8; while (bits_in_buffer < 8 && currentCharIndex < str.Length) { bit_buffer |= ValidChars.IndexOf(str[currentCharIndex++]) << bits_in_buffer; bits_in_buffer += 5; } } return bytes; } }
我需要一个base32编码器/解码器，所以我今天下午花了几个小时把它们放在一起。 我相信它符合这里列出的标准： http : //tools.ietf.org/html/rfc4648#section-6 。
public class Base32Encoding { public static byte[] ToBytes(string input) { if (string.IsNullOrEmpty(input)) { throw new ArgumentNullException("input"); } input = input.TrimEnd('='); //remove padding characters int byteCount = input.Length * 5 / 8; //this must be TRUNCATED byte[] returnArray = new byte[byteCount]; byte curByte = 0, bitsRemaining = 8; int mask = 0, arrayIndex = 0; foreach (char c in input) { int cValue = CharToValue(c); if (bitsRemaining > 5) { mask = cValue << (bitsRemaining - 5); curByte = (byte)(curByte | mask); bitsRemaining -= 5; } else { mask = cValue >> (5 - bitsRemaining); curByte = (byte)(curByte | mask); returnArray[arrayIndex++] = curByte; curByte = (byte)(cValue << (3 + bitsRemaining)); bitsRemaining += 3; } } //if we didn't end with a full byte if (arrayIndex != byteCount) { returnArray[arrayIndex] = curByte; } return returnArray; } public static string ToString(byte[] input) { if (input == null || input.Length == 0) { throw new ArgumentNullException("input"); } int charCount = (int)Math.Ceiling(input.Length / 5d) * 8; char[] returnArray = new char[charCount]; byte nextChar = 0, bitsRemaining = 5; int arrayIndex = 0; foreach (byte b in input) { nextChar = (byte)(nextChar | (b >> (8 - bitsRemaining))); returnArray[arrayIndex++] = ValueToChar(nextChar); if (bitsRemaining < 4) { nextChar = (byte)((b >> (3 - bitsRemaining)) & 31); returnArray[arrayIndex++] = ValueToChar(nextChar); bitsRemaining += 5; } bitsRemaining -= 3; nextChar = (byte)((b << bitsRemaining) & 31); } //if we didn't end with a full char if (arrayIndex != charCount) { returnArray[arrayIndex++] = ValueToChar(nextChar); while (arrayIndex != charCount) returnArray[arrayIndex++] = '='; //padding } return new string(returnArray); } private static int CharToValue(char c) { int value = (int)c; //65-90 == uppercase letters if (value < 91 && value > 64) { return value - 65; } //50-55 == numbers 2-7 if (value < 56 && value > 49) { return value - 24; } //97-122 == lowercase letters if (value < 123 && value > 96) { return value - 97; } throw new ArgumentException("Character is not a Base32 character.", "c"); } private static char ValueToChar(byte b) { if (b < 26) { return (char)(b + 65); } if (b < 32) { return (char)(b + 24); } throw new ArgumentException("Byte is not a value Base32 value.", "b"); } }
我已经写了一些基于灵活标准的各种Base32和Base64编码/解码方法的实现。 值得注意的是：base64url（每rfc4648）和它的base32相当。
默认情况下，Base32Url类仅使用字符A到Z和2到7进行编码。不使用连字符，下划线，加号，斜杠或等号，使其在几乎所有情况下都可用作URL标记。 Base32Url还支持自定义字母，区分大小写/不灵敏，填充/不填充等。
这张贴在代码项目上。
这是我的快速logging解决scheme。 它只适用于8个base32字符的倍数的string。 虽然工作，但。
public class Base32 { /// <summary> /// Decode a Base32 string /// This will only work on a multiple of 40 bits (5 bytes) /// http://www.garykessler.net/library/base64.html /// </summary> public static byte[] Decode(string Base32String) { // Ignore hyphens string str = Base32String.Replace("-", ""); // Convert it to bits List<byte> bits = new List<byte>(); foreach (char c in str) { int i = CharToValue(c); bits.Add((byte)((i & 16) > 0 ? 1 : 0)); bits.Add((byte)((i & 8) > 0 ? 1 : 0)); bits.Add((byte)((i & 4) > 0 ? 1 : 0)); bits.Add((byte)((i & 2) > 0 ? 1 : 0)); bits.Add((byte)((i & 1) > 0 ? 1 : 0)); } // Convert bits into bytes List<byte> bytes = new List<byte>(); for (int i = 0; i < bits.Count; i += 8) { bytes.Add((byte)( (bits[i + 0] << 7) + (bits[i + 1] << 6) + (bits[i + 2] << 5) + (bits[i + 3] << 4) + (bits[i + 4] << 3) + (bits[i + 5] << 2) + (bits[i + 6] << 1) + (bits[i + 7] << 0))); } return bytes.ToArray(); } static int CharToValue(char c) { char cl = char.ToLower(c); if (cl == 'a') return 0; if (cl == 'b') return 1; if (cl == 'c') return 2; if (cl == 'd') return 3; if (cl == 'e') return 4; if (cl == 'f') return 5; if (cl == 'g') return 6; if (cl == 'h') return 7; if (cl == 'i') return 8; if (cl == 'j') return 9; if (cl == 'k') return 10; if (cl == 'l') return 11; if (cl == 'm') return 12; if (cl == 'n') return 13; if (cl == 'o') return 14; if (cl == 'p') return 15; if (cl == 'q') return 16; if (cl == 'r') return 17; if (cl == 's') return 18; if (cl == 't') return 19; if (cl == 'u') return 20; if (cl == 'v') return 21; if (cl == 'w') return 22; if (cl == 'x') return 23; if (cl == 'y') return 24; if (cl == 'z') return 25; if (cl == '2') return 26; if (cl == '3') return 27; if (cl == '4') return 28; if (cl == '5') return 29; if (cl == '6') return 30; if (cl == '7') return 31; throw new Exception("Not a base32 string"); } }
我已经为VB.NET提出了自己的通用Base32编码器/解码器实现。 我已经通过独立的网站validation了结果，所以看起来相当准确。
任何关于如何改进代码的意见都会受到欢迎。
Option Compare Text Imports System.ComponentModel Public Structure Base32(Of T) Private Const csValidStandardBase32Chars As String = "0123456789ABCDEFGHIJKLMNOPQRSTUV" <EditorBrowsable(EditorBrowsableState.Never)> _ Class Base32Nibble <EditorBrowsable(EditorBrowsableState.Never)> _ Friend mStore As New BitArray(5, False) Public ReadOnly Property Value As Byte Get Dim result As Byte = 0 For index As Byte = 0 To mStore.Count - 1 If mStore(index) Then result += (2 ^ index) End If Next Return result End Get End Property Public Overrides Function ToString() As String Dim nibbleString As String = Nothing For Each bit As Boolean In mStore nibbleString = Math.Abs(CInt(bit)).ToString() & nibbleString Next Return nibbleString End Function End Class Private Shared mNibbles As List(Of Base32Nibble) Public ReadOnly Property Count As Long Get Return mNibbles.Count End Get End Property Default Public ReadOnly Property Item(ByVal index As Integer) As Base32Nibble Get Return DirectCast(mNibbles(index), Base32Nibble) End Get End Property Public Sub New(ByVal Value As T) Dim temp As Object = CType(Value, T) getNibbles(BitConverter.GetBytes(temp)) End Sub Public Sub New(ByVal Value As Byte()) getNibbles(Value) End Sub Public Shared Widening Operator CType(ByVal Value As T) As Base32(Of T) Return New Base32(Of T)(Value) End Operator Public Shared Widening Operator CType(ByVal Value As Byte()) As Base32(Of T) Return New Base32(Of T)(Value) End Operator Public ReadOnly Property Value As String Get Dim result As String = Nothing For Each Nib As Base32(Of T).Base32Nibble In mNibbles result = csValidStandardBase32Chars(Nib.Value) & result Next Return result.TrimStart("0") End Get End Property Public Function ToNumeric(ByVal Base32String As String) As T Dim result As T = CType(CType(0, Object), T) Try If Base32String.Trim.Length > 0 Then Dim pos As Integer = 0 Do Dim temp As Object = getBase32Value(Base32String, pos) result = result + temp pos += 1 Loop While (pos < Base32String.Length) End If Catch ex As Exception ' Catch overflow errors if the generic type T doesn't have enough ' room to store the result System.Diagnostics.Debug.Print(ex.Message) End Try Return result End Function Private Shared Sub getNibbles(ByVal Value As Byte()) Dim valueBytes As New BitArray(Value) Dim nib As Base32Nibble = Nothing mNibbles = New List(Of Base32Nibble) Dim padding As Byte = (1 - (valueBytes.Length / 5 - (valueBytes.Length \ 5))) * 5 valueBytes.Length = valueBytes.Length + padding For element As Short = 0 To valueBytes.Count - 1 If (element Mod 5 = 0) Then nib = New Base32Nibble() mNibbles.Add(nib) End If nib.mStore.Item(element Mod 5) = valueBytes.Item(element) Next End Sub Private Function getBase32Char(ByVal InputString As String, ByVal InputPosition As Integer) As String Return csValidStandardBase32Chars.IndexOf(Mid(InputString, InputPosition + 1, 1)) End Function Private Function getBase32Value(ByVal InputString As String, ByVal InputPosition As Integer) As T Return CType(CType((getBase32Char(InputString, InputPosition) * (32 ^ (InputString.Length - 1 - InputPosition))), Object), T) End Function End Structure
这是将123456789转换为Base32的一个例子
Dim value As Base32(Of Int64) = 123456789 Console.WriteLine( "123456789 in Base32 = " & value.Value)
这里是我的编码和解码function。 我觉得他们比其他build议简短得多。 所以，如果你需要一个小的，尝试这些。
public static string BytesToBase32(byte[] bytes) { const string alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"; string output = ""; for (int bitIndex = 0; bitIndex < bytes.Length * 8; bitIndex += 5) { int dualbyte = bytes[bitIndex / 8] << 8; if (bitIndex / 8 + 1 < bytes.Length) dualbyte |= bytes[bitIndex / 8 + 1]; dualbyte = 0x1f & (dualbyte >> (16 - bitIndex % 8 - 5)); output += alphabet[dualbyte]; } return output; } public static byte[] Base32ToBytes(string base32) { const string alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"; List<byte> output = new List<byte>(); char[] bytes = base32.ToCharArray(); for (int bitIndex = 0; bitIndex < base32.Length * 5; bitIndex += 8) { int dualbyte = alphabet.IndexOf(bytes[bitIndex / 5]) << 10; if (bitIndex / 5 + 1 < bytes.Length) dualbyte |= alphabet.IndexOf(bytes[bitIndex / 5 + 1]) << 5; if (bitIndex / 5 + 2 < bytes.Length) dualbyte |= alphabet.IndexOf(bytes[bitIndex / 5 + 2]); dualbyte = 0xff & (dualbyte >> (15 - bitIndex % 5 - 8)); output.Add((byte)(dualbyte)); } return output.ToArray(); }
