====== Concepts ====== ===== Signature Types According to Signature Structure ===== Signatures can be categorized into three classes according to the signature structure ^ Enveloping\\ | The data takes place in the signature as XML or Base64. | ^ Enveloped\\ | The data contains the signature. | ^ Detached\\ (Ayrık) | Signature and the signed data are seperate from each other. Especially for large data this type of signature is suggested. | ===== Signature Types ===== | **BES** \\ (Basic Electronic Signature) | The simplest form of signature with no timestamp | | **EPES** \\ (Explicit Policy Based Electronic Signature) | A special form of BES which includes policy signature information. | | **ES-T** \\ (Electronic Signature with Time) | EST signatures are created by adding a timestamp to a BES signature. | | **ES-C** \\ (Electronic Signature with Complete Validation Data References) | It is derived from ES-T by adding references to validation data. | | **ES-X** \\ (EXtended Electronic Signature) | Similar to ES-C,which additionally includes a timestamp over the validation references or the whole signed document. | | **ES-XL** \\ ((EXtended Long Electronic Signature) | Different from ES-C, it contains the validation data itself not the reference. | | **ES-A** \\ (Archival Electronic Signature) | A special form of signature which is protected by periodically generated timestamps against the danger of weakened cryptographich algorithms. |