# Padding Functions
[Cryptographic Functions]

## Functions

GWENHYWFAR_API int | GWEN_Padd_PaddWithANSIX9_23 (GWEN_BUFFER *src)
GWENHYWFAR_API int | GWEN_Padd_PaddWithISO9796 (GWEN_BUFFER *src)
GWENHYWFAR_API int | GWEN_Padd_PaddWithPkcs1Bt1 (GWEN_BUFFER *src, int dstSize)
GWENHYWFAR_API int | GWEN_Padd_PaddWithPkcs1Bt2 (GWEN_BUFFER *src, int dstSize)
GWENHYWFAR_API int | GWEN_Padd_UnpaddWithANSIX9_23 (GWEN_BUFFER *src)
GWENHYWFAR_API int | GWEN_Padd_UnpaddWithPkcs1Bt1 (GWEN_BUFFER *src)
GWENHYWFAR_API int | GWEN_Padd_UnpaddWithPkcs1Bt2 (GWEN_BUFFER *src)

## Detailed Description

These functions are used for padding when encrypting/decrypting data using 2-key-triple-DES or when signing data. The original code (in C++) has been written by Fabian Kaiser for OpenHBCI (file rsakey.cpp). Translated to C and slightly modified by me (Martin Preuss)

## Function Documentation

GWENHYWFAR_API int GWEN_Padd_PaddWithANSIX9_23 | ( | GWEN_BUFFER * | src | ) |

This function is used to pad the plain text data to a multiple of 8 bytes size before encrypting it. This is done by adding bytes to the buffer until its length is multiple of 8 bytes. The byte added is the number of padding bytes appended. Example: Buffer initially contains 5 bytes, so 3 bytes are needed to make the buffer length a multiple of 8. So the number "3" is added three times. Please note that if the buffer initially has a multiple of 8 bytes then 8 bytes are added (this is needed to make sure the unpadd function can always recover data padded in this manner).

GWENHYWFAR_API int GWEN_Padd_PaddWithISO9796 | ( | GWEN_BUFFER * | src | ) |

| This function padds the given buffer according to ISO9796. The given buffer is expected to contain a 20 byte hash created using RIPEMD 160. This is padded to 96 bytes according to ISO 9796 (including appendix A4).

GWENHYWFAR_API int GWEN_Padd_PaddWithPkcs1Bt1 | ( | GWEN_BUFFER * | src,
|  | int | dstSize
| ) |

GWENHYWFAR_API int GWEN_Padd_PaddWithPkcs1Bt2 | ( | GWEN_BUFFER * | src,
|  | int | dstSize
| ) |

GWENHYWFAR_API int GWEN_Padd_UnpaddWithANSIX9_23 | ( | GWEN_BUFFER * | src | ) |

| This function is used to remove padding from plain text data after decrypting it.

GWENHYWFAR_API int GWEN_Padd_UnpaddWithPkcs1Bt1 | ( | GWEN_BUFFER * | src | ) |

GWENHYWFAR_API int GWEN_Padd_UnpaddWithPkcs1Bt2 | ( | GWEN_BUFFER * | src | ) |