shift.c

#include <stdio.h>

void shift(unsigned char *a, int size, int shift) {
  int carry = 0 ;

  while (shift--) {
    carry = 0;

    for (int i = size - 1; i >= 0; i--) {
       int next = (a[i] & 1) ? 0x80 : 0 ;
       a[i] = carry | (a[i] >> 1) ;
       carry = next;
    }
  }
}

#define SIZE 40

int main() {
  unsigned char a[SIZE] =
  { '\xcb', '\xf0', '\x6a', '\x3f',
    '\x29', '\xff', '\xbf', '\xdc',
    '\xaf', '\xfc', '\x5b', '\xfe',
    '\xff', '\x67', '\x7c', '\xbe',
    '\x6a', '\x8e', '\x5a', '\x77',
    '\x06', '\x60', '\x45', '\x4a',
    '\x64', '\xe2', '\x66', '\x1e',
    '\x27', '\x84', '\xa5', '\xca',
    '\xc3', '\x00', '\x4a', '\x9c',
    '\xae', '\x70', '\x1f', '\xa7' } ;

  shift (a, SIZE, 6);

  for (int i = 0; i < SIZE; i++)
    printf("\\x%02x", a[i]);

  printf("\n");

  return 0;
}