Struct:ttEspAlgorithm

 
typedef struct tsEspAlgorithm {
    int             ealgName;
    ttUser8Bit      ealgBlockSize;  /* block size, in bytes */
    ttUser8Bit      ealgPaddingFlag;
    ttUser16Bit     ealgKeyMin;    /* in bits */
    ttUser16Bit     ealgKeyMax;    /* in bits */
    ttUser16Bit     ealgKeyDefault; /* use for IKE */
    int             (TM_CODE_FAR *ealgScheduleLenFuncPtr) (void);
    int             (TM_CODE_FAR *ealgScheduleFuncPtr) (
                                  struct tsEspAlgorithm TM_FAR * algPtr,
                                  ttGenericKeyPtr                keyPtr);
    int             (TM_CODE_FAR *ealgBlockDecryptFuncPtr) (
                                  struct tsEspAlgorithm TM_FAR * algPtr,
                                  ttGenericKeyPtr                keyPtr,
                                  ttUser8BitPtr                  srcPtr,
                                  ttUser8BitPtr                  dstPtr);
    int             (TM_CODE_FAR *ealgBlockEncryptFuncPtr) (
                                  struct tsEspAlgorithm TM_FAR * algPtr,
                                  ttGenericKeyPtr                keyPtr,
                                  ttUser8BitPtr                  srcPtr,
                                  ttUser8BitPtr                  dstPtr);
} ttEspAlgorithm;
typedef ttEspAlgorithm TM_FAR * ttEspAlgorithmPtr;
 

Structure Description

Any encryption algorithm must follow the format of ttEspAlgorithm. The user may use this format to add more encryption algorithms. See the examples of adding a ttAhAlgorithm. For encryption algorithms, the user needs to modify espAlgorithms in the file <trespcor.c>.

Members

• ealgName

  Algorithm name (i.e. SADB_EALG_DESCBC).

• ealgBlockSize

  Block size (in bytes) of this algorithm, generally, it is either 8 or 16 bytes.

• ealgPaddingFlag

  Indicates how to pad the ESP: either use the minimum length or a random length. Currently, set this flag to one. We do not support random size padding at this time.

• ealgKeyMin

  The minimum key size (in bits).

• ealgKeyMax

  The maximum key size (in bits).

• ealgKeyDefault

  The default key size (in bits).

• ealgScheduleLenFuncPtr

  A pointer to the function which computes the schedule length of this algorithm.

• ealgScheduleFuncPtr

  A pointer to the function which computes the schedule. This function will allocate memory for the schedule using the size computed from ealgScheduleLenFuncPtr, calculate the schedule, and save it into the generic key. The function prototype for the ealgScheduleFuncPtr is below.

• ealgBlockDecryptFuncPtr

  A pointer to the function which decrypts a single block of data using the key located in keyPtr.The function prototype for the ealgBlockDecryptFuncPtr is below.

• ealgBlockEncryptFuncPtr

  A pointer to the function which encrypts a single block of data using the key located in keyPtr.The function prototype for the ealgBlockEncryptFuncPtr is below.

Function Prototypes

ealgScheduleFuncPtr

 
int TM_CODE_FAR * ealgScheduleFuncPtr(struct tsEspAlgorithm TM_FAR * algPtr,
                                      ttGenericKeyPtr keyPtr);
 

ealgBlockDecryptFuncPtr

 
int TM_CODE_FAR * ealgBlockDecryptFuncPtr(struct tsEspAlgorithm TM_FAR * algPtr,
                                          ttGenericKeyPtr keyPtr,
                                          ttUser8BitPtr srcPtr,
                                          ttUser8BitPtr dstPtr);
 

ealgBlockEncryptFuncPtr

 
int TM_CODE_FAR * ealgBlockEncryptFuncPtr(struct tsEspAlgorithm TM_FAR * algPtr,
                                          ttGenericKeyPtr keyPtr,
                                          ttUser8BitPtr srcPtr,
                                          ttUser8BitPtr dstPtr);
 

Encryption Algorithm Key Length Table

Keylength (in bits)	Min	Max	Default
DES:	64	64	64
3DES:	192	192	192
Blowfish:	40	448	128
Cast128:	40	128	128
AES:	128	256	128
TWOFISH:	128	256	128

Note:

AES and Twofish keylength can be 128, 192 or 256 only.