Class EbicsFileSpoolerAccessControlList

Inheritance
System.Object
EbicsElement
EbicsFileSpoolerAccessControlList
Implements
System.Collections.Generic.IEnumerable<EbicsFileSpoolerAccessControlEntry>
System.Collections.IEnumerable
Inherited Members
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.ToString()
Namespace: Subsembly.EBICS
Assembly: Subsembly.EBICS.Core.dll
Syntax
public class EbicsFileSpoolerAccessControlList : EbicsElement, IEnumerable<EbicsFileSpoolerAccessControlEntry>, IEnumerable
Remarks

All files stored in the EbicsFileSpooler folder and all its sub-folders may be optionally encrypted and protected by individual user passwords. Only the entire folder tree with all its files can be protected, or none at all. It is not possible to protect some folders only.

If the storage folders are protected, then a ".access" (Access Control List) file exists at the root folder, and optionally at one or more sub-folders. A ".access" file contains entries for all users that have access to this folder, and implicitly also to all sub-folders of this folder. Hence, all users listed in the root ".access" file have access to the complete file spooler folder tree.

The root ".access" file must contain at least one entry for the "root" user. The "root" user has always access to the entire folder tree and is responsible for managing the other users access control list entries. The name of the root user is hard coded as "root" and cannot be changed. The access control list entry of the root user holds the root master key for encryption.

At the time when file protection is set up for the file spooler, the initial password of the "root" user is set and a master encryption key is created. Then all files that are already existing in the folder tree are encrypted with this master key. After that set up process is completed, it is no longer possible to access any files contained in the spooler folders without presenting valid user credentials.

IMPLEMENTATION NOTES

The root master key is used to derive individual folder encryption keys, based on the individual folder path and name. A folder key is computed from the parent folder key and the folder name using a one-way hash function: 

folder_key = hash(parent_folder_key, folder_name)
That way, every folder has its own individual encryption key. Still all folder keys can be derived from the root master key. As a one-way hash function is employed, it is not possible to derive a parent folder key from a folder key.

For each user in the user access control list the following tuple is stored. 

{user_name, hash(user_password), enc(folder-key, user_password)}
So the actual folder key is stored separately for every user, encrypted by the users password. Only when presenting the correct user name and corresponding password, the folder key can be decrypted and used to decrypt the files in this folder. Note that the folder key may also be used to derive any sub-folder keys. Hence, a user implicitly has access to all sub-folders, too.

ISSUES

Technically a user could create other users with the same privileges. Would be better if only the "root" user could create/manage other users.

Currently there are no sub-folders below the Partner-ID folder. Maybe it would be better to have additional sub-folders per account IBAN.

Maybe there should be a separate ".root" file that solely holds the root users credentials.

Properties

Count

Declaration
public int Count { get; }
Property Value
Type Description
System.Int32

Methods

AddAccessControlEntry(EbicsFileSpoolerAccessControlEntry)

Declaration
public void AddAccessControlEntry(EbicsFileSpoolerAccessControlEntry aACE)
Parameters
Type Name Description
EbicsFileSpoolerAccessControlEntry aACE

BuildXml(XmlDocument, EbicsVersion)

Declaration
public override XmlElement BuildXml(XmlDocument xmlDocument, EbicsVersion nVersion)
Parameters
Type Name Description
System.Xml.XmlDocument xmlDocument
EbicsVersion nVersion
Returns
Type Description
System.Xml.XmlElement
Overrides

DeleteUser(String)

Declaration
public bool DeleteUser(string sUserName)
Parameters
Type Name Description
System.String sUserName
Returns
Type Description
System.Boolean

FindUser(String)

Declaration
public EbicsFileSpoolerAccessControlEntry FindUser(string sUserName)
Parameters
Type Name Description
System.String sUserName
Returns
Type Description
EbicsFileSpoolerAccessControlEntry

GetEnumerator()

Declaration
public IEnumerator<EbicsFileSpoolerAccessControlEntry> GetEnumerator()
Returns
Type Description
System.Collections.Generic.IEnumerator<EbicsFileSpoolerAccessControlEntry>

ParseXml(XmlElement, EbicsVersion)

Declaration
public override void ParseXml(XmlElement xmlElement, EbicsVersion nVersion)
Parameters
Type Name Description
System.Xml.XmlElement xmlElement
EbicsVersion nVersion
Overrides

Explicit Interface Implementations

IEnumerable.GetEnumerator()

Declaration
IEnumerator IEnumerable.GetEnumerator()
Returns
Type Description
System.Collections.IEnumerator

Implements

System.Collections.Generic.IEnumerable<T>
System.Collections.IEnumerable