Example of Using TDES Functions¶
TDES Encryption and Decryption
// Use of the ECB mode
void TDES_sample(void){
// size of the TDES algorithm block is equal to 8
const int tdesBlkSize = 8;
// get size of the context needed for the encryption/decryption operation
int ctxSize;
ippsDESGetSize(&ctxSize);
// and allocate one
IppsDESSpec* pCtx1 = (IppsDESSpec*)( new Ipp8u [ctxSize] );
IppsDESSpec* pCtx2 = (IppsDESSpec*)( new Ipp8u [ctxSize] );
IppsDESSpec* pCtx3 = (IppsDESSpec*)( new Ipp8u [ctxSize] );
// define the key
Ipp8u key1[] = {0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08};
Ipp8u key2[] = {0x11,0x12,0x13,0x14,0x15,0x16,0x17,0x18};
Ipp8u key3[] = {0x21,0x22,0x23,0x24,0x25,0x26,0x27,0x28};
Ipp8u keyX[] = {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00};
// and prepare the context for the TDES usage
ippsDESInit(key1, pCtx1);
ippsDESInit(key2, pCtx2);
ippsDESInit(key3, pCtx3);
// define the message to be encrypted
Ipp8u ptext[] = {"the quick brown fox jumps over the lazy dog"};
// allocate enough memory for the ciphertext
// note that
// the size of ciphertext is always a multiple of the cipher block size
Ipp8u ctext[(sizeof(ptext)+desBlkSize-1) &~(desBlkSize-1)];
// encrypt (ECB mode) ptext message
// pay attention to the 'length' parameter
// it defines the number of bytes to be encrypted
ippsTDESEncryptECB(ptext, ctext, sizeof(ctext), pCtx1, pCtx2, pCtx3, IppsCPPaddingNONE);
// allocate memory for the decrypted message
Ipp8u rtext[sizeof(ctext)];
// decrypt (ECB mode) ctext message
// pay attention to the 'length' parameter
// it defines the number of bytes to be decrypted
ippsTDESDecryptECB(ctext, rtext, sizeof(ctext), pCtx1, pCtx2, pCtx3, IppsCPPaddingNONE);
// remove actual secret from contexts
ippsDESInit(keyX, pCtx1);
ippsDESInit(keyX, pCtx2);
ippsDESInit(keyX, pCtx3);
// release resources
delete (Ipp8u*)pCtx1;
delete (Ipp8u*)pCtx2;
delete (Ipp8u*)pCtx3;
}