@ PaulS
Thank you for the hint.
I replaced "Serial.print" with "Serial.write" and it worked!
here is the fix:-
//*******************************Arduino( A) *************************************************
byte crypt [8]={0x7E, 0x05, 0xBD, 0xEB, 0x1A, 0x3A, 0x6E, 0x91 };
void loop(){
for (int j=0;j<8;j++)
{
Serial.write(crypt[j]);
}
delay(1000);
}
what i get from serial monitor for this code is
~½ë:n //which doesn't matter how it looks
//**********************************************************************************************
I have connected the Rx of the arduino(A) to Tx of the arduino(B) and Tx to Rx.
//*********************************Arduino(B)******************************************************************
byte crypt [8];
void loop(){
while(Serial.available() <=0); // wait for incoming serial data
if (Serial.available() >=

// wait for four bytes
{
for(int i=0;i <=8; i++) crypt
=Serial.read();
for (int j=0;j<8;j++)
{
if (crypt[j]<0x10){
Serial.print("0");
}
Serial.print(crypt[j],HEX);
Serial.print(" ");
}
Serial.println("");
}
}
what i get from serial monitor for this code is
7E 05 BD EB 1A 3A 6E 91 //just like how i wanted it 
//*********************************************************************************************************************