Do you have a PDF document that requires a legally binding signature?

It doesn’t matter if it is a consulting agreement, a freelance contract, or a power of attorney, or minutes of a board meeting, you can easily get your PDF documents electronically signed with any of the many services that are available today.

Simply google, “sign pdf document” and you’ll get more than a quarter of a billion hits.

The question is, which of these free online e-signature services can you trust? What makes one more secure than others?


Before we go ahead and follow the instructions of this 90-second video on how to do so, it’s important that we discuss the different types of e-signatures, and more specifically, the difference between a digital signature and an electronic signature and what makes one more secure than the other (latter).

The difference between a simple electronic signature and digital signature

The terms electronic signature and digital signature are used interchangeably but essentially these two concepts are different.

In the broadest sense, a digital signature comes with a seal authorized by certification authorities (also known as CAs) such as Adobe Approved Trust List and is used when securing the signed document from tampering is a concern.

An electronic signature, on the other hand, is often used to show an intention to sign a document and to execute an agreement. Although it is legally binding when signed by both parties, it is not usually authorized by CAs and cannot be easily verified.

In other words, digital signatures are like electronic fingerprints and electronic signatures are like handwritten signatures on paper.

Who are the certification authorities?

As discussed, a digital signature is authorized and regulated by certification authorities. A CA is an entity that issues digital certificates. An example of a CA, that Oneflow’s digital signature relies upon, is Adobe Approved Trust List.

The digital certificate certifies the ownership of a public key by the named owner of the certificate. This enables other parties to rely upon signatures made by the private key that corresponds to the public key that is certified.

Therefore, a CA is a trusted third party that is independent to both the owner of the certificate and the party relying upon the certificate.

Securing your PDF document with a digital signature

In other words, a contractual agreement signed with a digital signature can be independently verified by the CA, who acts as the trusted third party or a guarantor. The parties involved in the agreement do not have to rely on the electronic signature provider.

So if someone unauthorized tampers with the signed contract, the key will be altered and will not match the key stored in the digital certificate, providing clear evidence that the signed contract has been tampered with after it is signed.

difference digital signature electronic signature

A simple electronic signature that is signed without an authorized seal, on the other hand, does not come with a key authorized by a CA, therefore there is no trusted third party who can prove any tampering of the signed contracts nor certify the validity of the signed contract.

Questions to ask before signing a PDF document online

As we previously mentioned, there are many online services that are available free today. If you are looking to sign your PDF document with secure, reliable signatures that can be verified even if the provider disappears from the Earth, then remember to ask these questions:

Does the online signature comes with a seal?
If yes, is the seal authorized by a CA?

Most providers don’t offer authorized digital signatures because it comes with a price. For every digital certificate that is issued by a CA, there is a cost borne by the provider.

Sign your PDF documents with digital signatures today

Every signed contract in Oneflow is sealed with a Qualified Electronic Seal, i.e essentially a “digital signature”. It doesn’t matter if you’re using the trial or paid version.

The authorized seal used by Oneflow is applied by our partner Sovos TrustWeaver.

The seal prevents both intentional and accidental change the PDF document after it was signed, meaning you and your counterparties can remain secure in the knowledge that what you signed today will remain verifiably unchanged now and in the future, even if that is 20 years away.

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Here’s how to get started with digital signatures in 90 seconds