S. 145 : Method of accounting-Survey-Estimation of income-Assessee has shown net profit of 2 %-AO estimated net profit at 5%-Reported a profit of 8% in earlier years-Estimate of income at 5% is affirmed-Assessment order and intimation bearing DIN were uploaded on revenue’s portal-Assessee can not challenge validity of assessment order for lack of DIN-Assessment-Digital signature-On account of technical issues departmental authorities were prevented from making digital signatures, prompting manual signing of assessment order-Orders were uploaded and sent to assessee’s registered email ID, it was deemed to be authenticated and therefore, assessment order was valid.[S. 133A, 143(3),, 144, 147, 148,156, 271A, 271B, 282A(2)R. 127A]