DSC Signing Only vs Signing + Encryption: Class 3 Digital Signature Usage in India (2026)
When you buy a Class 3 Digital Signature Certificate (DSC) in India, you are usually asked to choose between a “Signing only” certificate and a “Signing + Encryption” (combo) certificate. The two look similar and often cost about the same, but they do very different jobs. This guide explains the difference in plain language so you pick the right variant the first time and avoid buying a second token later.
What a Class 3 DSC Actually Is
Since Class 2 certificates were phased out, Class 3 is the standard DSC for almost all business and statutory filings in India. It is issued by licensed Certifying Authorities (CAs) under the Controller of Certifying Authorities (CCA) and, by regulation, the private keys must be stored on a secure FIPS-compliant USB crypto token (you cannot simply keep the key as a file on your computer).
Within Class 3, the certificate can carry two distinct capabilities, and this is where the “signing only” versus “signing + encryption” choice comes in.
The Signing Key
A signing certificate is used to digitally sign documents and forms. It proves two things: who signed (authenticity) and that the content was not altered after signing (integrity). Under the Information Technology Act, 2000, a valid digital signature carries the same legal standing as a handwritten signature.
The Encryption Key
An encryption certificate does the opposite job. Instead of proving identity, it locks (encrypts) data so that only the intended recipient can unlock (decrypt) and read it. It protects confidentiality of the information rather than signing it.
Signing Only vs Signing + Encryption
A “Signing only” certificate contains just the signing key pair. A “Signing + Encryption” certificate (commonly called a combo or dual certificate) bundles two separate key pairs on the same token: one for signing and one for encryption. Both are Class 3; the difference is purely in what functions they can perform.
| Feature | Signing Only | Signing + Encryption (Combo) |
|---|---|---|
| Primary purpose | Sign documents & forms | Sign documents & also encrypt/decrypt data |
| Ensures | Authenticity & integrity | Authenticity, integrity & confidentiality |
| Key pairs on token | One (signing) | Two (signing + encryption) |
| Typical use cases | MCA/ROC, GST, Income Tax, DGFT, EPFO, PAN/TAN | e-Tendering, e-Procurement, e-Auction & portals needing secure bid upload |
| Legal validity of signature | Yes, under IT Act 2000 | Yes, under IT Act 2000 |
| Validity period | 1 to 3 years | 1 to 3 years |
| USB token required | Yes | Yes |
Where Signing Only Is Enough
For the vast majority of routine statutory and tax compliance, a signing-only Class 3 DSC does everything you need. The portal only needs to confirm your identity and that the form was not tampered with after you signed it.
- MCA / ROC filings (company incorporation, annual returns, DIN, forms)
- GST registration and returns
- Income Tax return filing and tax audit uploads
- DGFT (Import Export Code and foreign trade filings)
- EPFO, ESIC and various e-Governance submissions
If your work is limited to these, paying for encryption you will never use adds no benefit.
Where Signing + Encryption Is Needed
The encryption key matters when a portal requires you to submit information in a confidential, sealed form so that competitors or third parties cannot read it before the official opening. This is most common in tender and auction platforms.
- e-Tendering and e-Procurement portals (Central and State government, PSUs)
- Platforms such as GeM, CPPP/eProcure and MSTC where bids or price data are encrypted
- e-Auctions where sealed, confidential bid values are uploaded
- Situations involving exchange of highly confidential or financial data
On these portals the bid must stay encrypted until the tender opening time, which is exactly what the encryption certificate enables. Buying a signing-only DSC and later discovering the tender portal demands encryption usually means buying a fresh combo token, so it is worth checking the portal’s requirement in advance.
A Note on Key Backup
There is one practical difference between the two keys. A signing key should be unique and is never backed up, which is what keeps a signature trustworthy. An encryption key, however, may be backed up by the Certifying Authority so that encrypted data can still be recovered if the token is lost. This is normal and does not weaken your signature.
How to Choose
The decision is simple. If you participate in government tenders, e-procurement or e-auctions, choose Signing + Encryption. If you only file with MCA, GST, Income Tax or DGFT, a Signing only certificate is sufficient. When in doubt, a combo certificate is the safer, future-proof pick because it covers both scenarios on a single token. If you would like help deciding, our team can guide you through the right Class 3 digital signature certificate for your filings.
Frequently Asked Questions
Is a signing-only DSC legally valid for tax and MCA filings?
Yes. A Class 3 signing certificate is legally valid under the Information Technology Act, 2000 and is accepted for MCA/ROC, GST, Income Tax and DGFT filings. The encryption key is not required for these portals.
Do I need the combo certificate for e-tendering?
Most e-tendering and e-procurement portals require encryption so that bids remain confidential until opening. For these, a Signing + Encryption (combo) Class 3 DSC is generally required. Always confirm the specific portal’s requirement before buying.
Can I upgrade a signing-only DSC to add encryption later?
A certificate’s capabilities are fixed at the time of issue, so you normally cannot add an encryption key to an existing signing-only certificate. You would apply for a fresh combo certificate. This is why many buyers choose the combo upfront if there is any chance of tender work.
How long is a Class 3 DSC valid and does it need a token?
Class 3 DSCs are typically issued for 1 to 3 years, and both signing-only and combo variants must be stored on a secure FIPS-compliant USB crypto token as per CCA norms.
Does the combo certificate cost much more?
Pricing varies by Certifying Authority and validity period, and the encryption add-on is often a modest difference. Always compare the total cost including the USB token, and confirm current pricing with your provider before purchase.
Get the Right DSC the First Time
Choosing between a signing-only and a signing + encryption Class 3 certificate comes down to whether tenders and confidential uploads are part of your work. If you are unsure, TAXAJ can assess your filing needs and help you buy a compliant DSC and token without overpaying or under-buying. Reach out and we will make the process quick and correct.
