what is digital signature certificate

{"cid":"91226353","title":"2540 LPI Signature Fingerprint Modules Voter ID Registration Kiosk FBI FAP 60 Certification","imgUrl":"https:\/\/img.chinax.com\/nimg\/8c\/f8\/7fba6c6bdd7d9084c09abd2dbb4d-200x200-1.jpg","attrs":{"Price":"USD 200-400 \/ Piece","Brand Name":"OEM","Model Number":"A910S","Minimum Order Quantity":"100 Pieces","Delivery Time":"15-30 days after order confirmation","Supply Ability":"5000 Pieces per Month","Certification":"FBI Appendix F FAP 60, FCC, CE, RoHS","Payment Terms":"T\/T, PayPal, Western Union","Signature Technology":"Electromagnetic","Operating Humidity":"10% - 93% R.H.","Working Temperature":"-20 C to +60 C","Signature Active Area":"86mm x 76.2mm","Place of Origin":"Taiwan, China","Model":"A910S","Fingerprint Capture":"4-4-2 flats and rolled prints","Packaging Details":"Anti-static protective packaging with export-grade carton","Signature Resolution":"2540 LPI","Application":"Voter Registration, Civil Registration, National ID","Interface":"USB 2.0"}}

{"cid":"91219627","title":"Visa Card Reader Handheld Pos Devices 60mm EMV Certificate With 2 PSAM Slot","imgUrl":"https:\/\/img.chinax.com\/nimg\/bd\/dd\/62f83cfef4d660d139de0898a729-200x200-1.jpg","attrs":{"Price":"US$25-35\/pc","Brand Name":"Tianyu","Model Number":"MP45","Minimum Order Quantity":"1pc","Delivery Time":"2-15days","Certification":"ISO ,Test Report,3C,RoHs","Place of Origin":"China","Payment Terms":"T\/T, Western Union, ","Supply Ability":"20000-40000\/Month","Packaging Details":"Standard carton box","Brand name":"Tianyu","Power & Battery":"Battery lasts for more than 500 transactions by Magnetic Stripe Card or IC Card","Dimension":"111mm*60mm*12mm (approx.)","Programmable":"Support Secondary Development","Certificate":"PCI PTS, EMV L1 & L2","Power":"Battery lasts for more than 500 transactions by Magnetic Stripe Card or IC Card"}}