A lock assembly for use with a door-lock mechanism, the lock assembly comprising: (a) an anterior portion sub-assembly including: (i) a push button; and (ii) an exterior drive handle, wherein said exterior drive handle is adapted for rotational motion around said push button; (b) an intermediate portion sub-assembly including: (i) a lock-cylinder like shaped casing; and (ii) a sprocket wheel, adapted for rotational motion with relation to said lock-cylinder like shaped casing so as to operatively engage the internal mechanism of the door-lock, (iii) a sprocket wheel cylinder for transferring torque from said exterior drive handle for rotating said sprocket wheel, mounted at least partially inside said lock-cylinder like shaped casing; (iv) a square recess of position selector for transferring rotational torque from said exterior drive handle, said square recess of position selector being mounted at least partially inside said lock-cylinder like shaped casing, wherein said intermediate portion sub-assembly is operatively connected to said anterior portion sub-assembly; and (c) a posterior portion sub-assembly including: (i) a housing; (ii) a printed circuit board mounted inside said housing; (iii) an electric motor mounted inside said housing, wherein said posterior portion sub-assembly is operatively connected to said intermediate portion sub-assembly; (iv) a rod for transferring rotational torque and for transferring linear force, said rod is mounted partially inside said housing; (v) a micro-switch tongue disposed on said rod; (vi) at least one micro-switch disposed on said printed circuit board; (vii) a cam operatively connected to said electric motor: (viii) a power supply operatively connected to said electric motor; (ix) a hollow cylinder disposed on said rod; (x) a stopping member disposed on said rod; and (xi) a flap disposed on said stopping member. (a) an anterior portion sub-assembly including: (i) a push button; and (ii) an exterior drive handle, wherein said exterior drive handle is adapted for rotational motion around said push button; (i) a push button; and (ii) an exterior drive handle, wherein said exterior drive handle is adapted for rotational motion around said push button; (b) an intermediate portion sub-assembly including: (i) a lock-cylinder like shaped casing; and (ii) a sprocket wheel, adapted for rotational motion with relation to said lock-cylinder like shaped casing so as to operatively engage the internal mechanism of the door-lock, (iii) a sprocket wheel cylinder for transferring torque from said exterior drive handle for rotating said sprocket wheel, mounted at least partially inside said lock-cylinder like shaped casing; (iv) a square recess of position selector for transferring rotational torque from said exterior drive handle, said square recess of position selector being mounted at least partially inside said lock-cylinder like shaped casing, wherein said intermediate portion sub-assembly is operatively connected to said anterior portion sub-assembly; and (i) a lock-cylinder like shaped casing; and (ii) a sprocket wheel, adapted for rotational motion with relation to said lock-cylinder like shaped casing so as to operatively engage the internal mechanism of the door-lock, (iii) a sprocket wheel cylinder for transferring torque from said exterior drive handle for rotating said sprocket wheel, mounted at least partially inside said lock-cylinder like shaped casing; (iv) a square recess of position selector for transferring rotational torque from said exterior drive handle, said square recess of position selector being mounted at least partially inside said lock-cylinder like shaped casing, wherein said intermediate portion sub-assembly is operatively connected to said anterior portion sub-assembly; and (c) a posterior portion sub-assembly including: (i) a housing; (ii) a printed circuit board mounted inside said housing; (iii) an electric motor mounted inside said housing, wherein said posterior portion sub-assembly is operatively connected to said intermediate portion sub-assembly; (iv) a rod for transferring rotational torque and for transferring linear force, said rod is mounted partially inside said housing; (v) a micro-switch tongue disposed on said rod; (vi) at least one micro-switch disposed on said printed circuit board; (vii) a cam operatively connected to said electric motor: (viii) a power supply operatively connected to said electric motor; (ix) a hollow cylinder disposed on said rod; (x) a stopping member disposed on said rod; and (xi) a flap disposed on said stopping member. (i) a housing; (ii) a printed circuit board mounted inside said housing; (iii) an electric motor mounted inside said housing, wherein said posterior portion sub-assembly is operatively connected to said intermediate portion sub-assembly; (iv) a rod for transferring rotational torque and for transferring linear force, said rod is mounted partially inside said housing; (v) a micro-switch tongue disposed on said rod; (vi) at least one micro-switch disposed on said printed circuit board; (vii) a cam operatively connected to said electric motor: (viii) a power supply operatively connected to said electric motor; (ix) a hollow cylinder disposed on said rod; (x) a stopping member disposed on said rod; and (xi) a flap disposed on said stopping member.