Implementation of LDAP Distinguished Name parser, based on http://stackoverflow.com/a/25335936/137854. Also trims leading whitespace from attribute names and handles quoted values e.g. the `O="VeriSign, Inc."` in `CN=VeriSign Class 3 Secure Server CA - G3, OU=Terms of use at https://www.verisign.com/rpa (c)10, OU=VeriSign Trust Network, O="VeriS…

DistinguishedName.cs

public class DistinguishedName
{
  /// <summary>
  /// Represents a name/value pair within a distinguished name, including the index of the part.
  /// </summary>
  public struct Part
  {
    public Part(string name, string value, int index = -1)
      : this()
    {
      Name = name;
      Value = value;
      Index = index;
    }

    public string Name { get; private set; }
    public string Value { get; private set; }
    public int Index { get; private set; }

    /// <summary>
    /// Performs a case-insensitive name comparison
    /// </summary>
    /// <param name="name"></param>
    /// <returns></returns>
    public bool IsNamed(string name)
    {
      return string.Equals(name, this.Name, StringComparison.OrdinalIgnoreCase);
    }
  }

  /// <summary>
  /// Parses the given distinguished name into parts
  /// </summary>
  /// <param name="dn"></param>
  /// <returns></returns>
  public static IEnumerable<Part> Parse(string dn)
  {
    int i = 0;
    int a = 0;
    int v = 0;
    int index = -1;

    bool inNamePart = true;
    bool isQuoted = false;
    var namePart = new char[50];
    var valuePart = new char[200];

    string attrName, attrValue;

    while (i < dn.Length)
    {
      char ch = dn[i++];

      if (!inNamePart && ch == '"')
      {
        isQuoted = !isQuoted;
        continue;
      }

      if (!isQuoted)
      {
        if (ch == '\\')
        {
          valuePart[v++] = ch;
          valuePart[v++] = dn[i++];
          continue;
        }

        if (ch == '=')
        {
          inNamePart = false;
          isQuoted = false;
          continue;
        }

        if (ch == ',')
        {
          inNamePart = true;

          attrName = new string(namePart, 0, a);
          attrValue = new string(valuePart, 0, v);

          yield return new Part(attrName, attrValue, ++index);

          isQuoted = false;

          a = v = 0;
          continue;
        }
      }

      if (inNamePart && a == 0 && char.IsWhiteSpace(ch)) // skip whitespace
        continue; 

      else if (inNamePart)
        namePart[a++] = ch;

      else
        valuePart[v++] = ch;
    }

    attrName = new string(namePart, 0, a);
    attrValue = new string(valuePart, 0, v);

    yield return new Part(attrName, attrValue, ++index);
  }
}