我有一个base32字符串,需要将其转换为字节数组。但我在.NET框架中找不到相应的转换方法。我能找到base64的方法,但没有base32的。
类似Convert.FromBase64String
这样的方法,如果有一个对于base32的方法就太完美了。
在.NET框架中是否有这样的方法,还是说我必须自己实现?
我有一个base32字符串,需要将其转换为字节数组。但我在.NET框架中找不到相应的转换方法。我能找到base64的方法,但没有base32的。
类似Convert.FromBase64String
这样的方法,如果有一个对于base32的方法就太完美了。
在.NET框架中是否有这样的方法,还是说我必须自己实现?
我需要一个base32编解码器,所以今天下午花了几个小时把它搞定。我相信它符合这里列出的标准:https://www.rfc-editor.org/rfc/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");
}
}
请查看这个针对.NET的FromBase32String
实现,可以在此处找到。
编辑:上面的链接已经失效,您可以在archive.org中找到存档副本。
实际代码如下:
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;
}
}
FromBase32String()
对于无效字符不会抛出ArgumentException
(或任何其他异常) - 因为IndexOf
也不会。
如果未找到字符,IndexOf
将返回-1。 - spacerstring
定义一个扩展方法,例如 "IndexOfEx",它会抛出异常而不是返回 -1。 - spacerpublic 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 / 5 + 1 < bytes.Length; 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();
}
for
循环条件更改为 bitIndex / 5 + 1 < bytes.Length
。 - Patrickbase32.ToCharArray()
,而是使用StringBuilder
。还可以通过预先分配对话所需的数据来进一步改进它。(并在函数之间重用常量) - NiKiZebase32.ToCharArray()
,而是使用StringBuilder
。还可以通过预先分配对话所需的数据来进一步改进代码(并在函数之间重用常量)。 - undefined这是一个很老的问题,但我碰巧想要为OTP令牌做同样的事情。结果发现OTP.NET包中有内置的32进制功能:
Base32Encoding.ToBytes("(your base 32 string here)")
Base32Encoding.ToString(new byte[] { /* your bytes here */ })
我编写了一些基于灵活的标准实现的各种Base32和Base64编码/解码方法,特别是:base64url(按照rfc4648)及其base32等效。
默认情况下,Base32Url类仅使用A到Z和2到7这些字符进行编码。不使用连字符、下划线、加号、斜杠或等号,使其可用作URL令牌在几乎所有情况下。Base32Url还支持自定义字母表、区分大小写/不区分大小写、填充/不填充等功能。
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开发了自己的通用Base32编码器/解码器实现。我已经通过独立的网站验证了结果,因此它似乎非常准确。
欢迎提出有关如何改进代码的任何评论。
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的示例
Dim value As Base32(Of Int64) = 123456789
Console.WriteLine( "123456789 in Base32 = " & value.Value)