我有一个base32字符串,我需要将其转换为字节数组.我在.NET框架中找到转换方法时遇到了麻烦.我可以找到base64的方法,但不能找到base32的方法.
Convert.FromBase64String - 像base32这样的东西是完美的.
在框架中是否有这样的方法或者我必须自己滚动？
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.我相信它符合此处列出的标准: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");
}
}
检查此处的FromBase32String .NET实现.
编辑:上面的链接已经死了; 您可以在archive.org上找到存档的副本
实际代码读取:
using System;
using System.Text;
public sealed class Base32 {
// the valid chars for the encoding
private static string ValidChars = "QAZ2WSX3" + "EDC4RFV5" + "TGB6YHN7" + "UJM8K9LP";
///
/// Converts an array of bytes to a Base32-k string.
///
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();
}
///
/// Converts a Base32-k string into an array of bytes.
///
///
/// Input string s contains invalid Base32-k characters.
///
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;
}
}
我已经编写了一些基于标准的灵活的各种Base32和Base64编码/解码方法的实现.值得注意的是:base64url(每rfc4648)及其base32等价物.
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,这使得它几乎可以在所有情况下用作URL令牌.Base32Url还支持自定义字母,区分大小写/不敏感,填充/无填充等.
这是在代码项目上发布的.
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