LegacyPasswordReader.cs

/*
 * NanoXLSX is a small .NET library to generate and read XLSX (Microsoft Excel 2007 or newer) files in an easy and native way
 * Copyright Raphael Stoeckli © 2025
 * This library is licensed under the MIT License.
 * You find a copy of the license in project folder or on: http://opensource.org/licenses/MIT
 */
 
using System;
using System.Xml;
using NanoXLSX.Exceptions;
using NanoXLSX.Interfaces;
using NanoXLSX.Interfaces.Reader;
using NanoXLSX.Registry;
using NanoXLSX.Registry.Attributes;
using static NanoXLSX.Internal.Enums.ReaderPassword;
 
namespace NanoXLSX.Internal.Readers
{
    [NanoXlsxPlugIn(PlugInUUID = PlugInUUID.PasswordReader)]
    public class LegacyPasswordReader : IPasswordReader
    {
        private string passwordHash;

        public virtual bool ContemporaryAlgorithmDetected { get; private set; }

        public virtual PasswordType Type { get; private set; }

        public virtual ReaderOptions Options { get; private set; }

        public virtual string PasswordHash
        {
            get { return passwordHash; }
            set { passwordHash = value; }
        }
 

        internal LegacyPasswordReader()
        {
        }

        public virtual void Init(PasswordType type, ReaderOptions readerOptions)
        {
            this.Type = type;
            this.Options = readerOptions;
        }

        public virtual void ReadXmlAttributes(XmlNode node)
        {
            string attribute;
            if (Type == PasswordType.WorkbookProtection)
            {
                attribute = ReaderUtils.GetAttribute(node, "workbookAlgorithmName");
            }
            else
            {
                attribute = ReaderUtils.GetAttribute(node, "algorithmName");
            }
            if (attribute != null)
            {
                if (Options.IgnoreNotSupportedPasswordAlgorithms)
                {
                    this.ContemporaryAlgorithmDetected = true;
                }
                else
                {
                    throw new NotSupportedContentException("A not supported, contemporary password algorithm for the worksheet protection was detected. Check possible packages to add support to NanoXLSX, or ignore this error by a reader option");
                }
            }
 
            if (Type == PasswordType.WorkbookProtection)
            {
                attribute = ReaderUtils.GetAttribute(node, "workbookPassword");
                if (attribute != null)
                {
                    this.PasswordHash = attribute;
                }
            }
            else
            {
                attribute = ReaderUtils.GetAttribute(node, "password");
                if (attribute != null)
                {
                    this.PasswordHash = attribute;
                }
            }
        }

        public virtual string GetPassword()
        {
            return null; // The reader cannot recover the plain text password
        }

        public virtual bool PasswordIsSet()
        {
            return passwordHash != null || ContemporaryAlgorithmDetected;
        }

        public virtual void CopyFrom(IPassword passwordInstance)
        {
            throw new NotImplementedException();
        }

        public virtual void SetPassword(string plainText)
        {
            throw new NotImplementedException();
        }

        public virtual void UnsetPassword()
        {
            throw new NotImplementedException();
        }
    }
}