A digital signature is an electronic signature which is used to verify whether an electronic document is authentic. Individuals use digital signature certificates (DSCs) to ensure that electronic documents shared using the internet are not tampered with. Hackers cannot view or modify documents which are signed using a valid class 3 DSC.

A digital signature comes with two keys – a public key and a private key. These keys are used to encrypt and decrypt the shared data. The owner can share his/her public key which is used to encrypt information. This information can be decrypted only with an appropriate key. Without a key to decrypt the message, the encrypted data cannot be read by any unauthorised user. Certificate owners should save their private key in a secure manner.

In India, class 3 digital signature certificates are issued to individuals as well as organisations. For issuance of a Safescrypt(SIFY) class 3 digital signature certificate, applicants have to appear in person to confirm their identity.

Safescrypt(SIFY) class 3 DSC can be purchased online at http://psquaretec.com/. The certificate will be delivered to within seven working days. VASCO digipass key is provided with every sify digital signature certificate.

SIFY class 3 digital signature certificates are used for online tenders of:

Bharat Heavy Electricals Limited (BHEL)
Government of Madhya Pradesh
Indian Space Research Organization (ISRO)
National Thermal Power Corporation Limited (NTPC)
Oil and Natural Gas Corporation Limited (ONGC)
Power Grid Corporation of India Limited (PGCIL)
Hindustan Petroleum Corporation Limited (HPCL)
Indian Ordnance Factories
Northern Railway
Coal India Limited
Indian Oil Corporation
Indian Farmers Fertilizer Co-Operative (IFFCO)
Hindustan Aeronautics Limited (HAL)
South Central Railway
Brihanmumbai Electric Supply and Transport (BEST)
National Highways Authority of India (NHAI)
Gas Authority of India Limited (GAIL)
Association of State Road Transport Undertakings [ASRTU]
Bharat Sanchar Nigam Limited [BSNL]
Centre for Development of Imaging Technology, Kerala [CDIT]
Delhi Development Authority [DDA]
Cochin Port Trust [CPT]
Container Corporation of India Limited [CONCOR]
Kerala State Poultry Development Corporation Limited [KEPCO]
Central Public Works Department [CPWD]
Director General Naval Projects Visakhapatnam [DGNPV]
Electronics Corporation of Tamil Nadu [ELCOT]
Himachal Road Transport Corporation [HRTC]
Hindustan Newsprint Limited [HNL]
Indian Institute of Management Bangalore [IIMB]
Jawaharlal Nehru Port Trust [JNPT]
JIPMER [Puducherry]
Kerala Transport Development Finance Corporation Limited [KTDFC]
Kerala State Civil Supplies Corporation Ltd. [KSCSC]
Kerala Sustainable Urban Development Project [KSUDP]
Kerala Water Authority [KWA]
National Institute of Ocean Technology [NIOT]
Public Works Department, Government of Puducherry [PWDPON]
Power Transmission Corporation of Uttarakhand Limited [PTCUL]
Satluj Jal Vidyut Nigam Limited [SJVNL]
Tehri Hydro Development Corporation Limited [THDC]
Uttarakhand Power Corporation Limited [UPCL]
Union Territory of Lakshadweep [UTL]

Safescrypt(SIFY) class 3 digital signature certificate is also used in Patent e-filing and Trademark e-filing

Class 3 digital signature certificates come with a validity of one or two years. Every certificate comes with a start date and an expiry date. When a user submits an online application using a DSC, the validity period of a certificate is checked. The expiry dates of certificates issued are added to the certificate revocation list (CRL). Once the certificate is invalid, it is removed from the revocation list.