@CHIP-RTOS C Library - TCP/IP API

Crypt_3DES_Decrypt

Decrypt one cipher block of data using 3DES decryption method.

int far Crypt_3DES_Decrypt (
             const Crypt_3DesKeyScheduleS far *schedule,
             const void far *in,
                   void far *out ) ;

Parameters

schedule

Pointer to 3DES subkey schedule generated by Crypt_3DES_MakeKey().

in

Pointer to 8 byte cipher text to be decrypted

out

Pointer to 8 byte buffer where the resulting decrypted clear text will be written by this API.

Return Value

0 constant (provisional error code)

Comments

This API decrypts one 8 byte cipher block of data using the 3DES decryption method.   It can be called repeatedly until your entire message has been recovered.   When your message is not an integral number of 8 byte blocks in length, then you will obtain on the final call the pad bytes that were appended to the original message at the encryption step.

The 3DES cipher treats data as little endian long words.   Any required data endian handling is done inside this API, so the caller must not perform any such handling on their side.   (Since the @CHIP-RTOS-x86 CPU is itself little endian, this note applies only for code which is to be ported to big endian Beck platforms.)

The in and out parameters may reference the same location.

Go here for a summary of cipher method execution times.

See Also

Crypt_3DES_Encrypt        Crypt_3DES_MakeKey        Crypt_DES_Decrypt

RTOS API

On the first call, this library function invokes a software interrupt which modifies the code at the calling site inside your application program.   A direct FAR JMP into the @CHIP-RTOS-x86 implementation for this function is installed so that on return and on any subsequent calls to this API this dynamic link reaches the function's implementation directly.

Supported since or modified in @CHIP-RTOS version

SC12	SC13	SC11	SC1x3	SC2x
n/a	n/a	n/a	V1.35	V1.35

Supported by @CHIP-RTOS C Library since version

CLIB
V2.19