how to validate digital signature

{"cid":"91105416","title":"Restaurant Dual Touch Screen Promotional Kiosk , Coin Kiosk","imgUrl":"https:\/\/img.ismap.com\/nimg\/db\/e1\/de3c3af1e723689b8b327fd666ba-200x200-1.jpg","attrs":{"Brand Name":"LKS \/ ODM \/ OEM","Model Number":"LKS8501B","Minimum Order Quantity":"5 Units","Delivery Time":"4-6 weeks upon payment","Certification":"CE, FCC","Place of Origin":"China","Payment Terms":"T\/T in advance, Western Union, L\/C","Supply Ability":"1000 units per month","Packaging Details":"Film wrap, foam and wooden box","Cheque":"Scan and storage","Billnote":"Validate and accept","Receipt printer":"80 mm width"}}

{"cid":"91199076","title":"Environment Friendly PVC smart card chip card For Access Control & Security","imgUrl":"https:\/\/img.ismap.com\/nimg\/e9\/17\/51550d4653a366ed3c07b440921c-200x200-1.jpg","attrs":{"Price":"Negotiable","Brand Name":"Wisecard","Model Number":"Smart Magstripe Card","Minimum Order Quantity":"Negotiable","Delivery Time":"7 week days","Place of Origin":"Shenzhen","Certification":"ISO14443,7816, CR80","Payment Terms":"T\/T","Supply Ability":"100,000 pcs per week","Packaging Details":"200pcs\/box, 10boxes\/carton; For standard size card or customized boxes or cartons as required.","Security":"Encryption","Application":"Public Transportation, Access Management, Club Visiting, Etc.","Data Transfer":"Contactless","Size":"CR80 85.5*54mm As Credit Card","Surface effect":"Glossy, Matt, Glitter, Metallic, Laser, Or With Overlay For Thermal Printer","Authentication":"Digital Signature","Material":"PVC \/ ABS \/ PET Etc.","Printing":"Heidelberg Offset Printing\/Pantone Color Printing\/Screen Printing"}}