What Is A Blind Signature?

Have you ever wondered how other nations have successfully implemented electronic voting while maintaining voter anonymity? And how do digital currencies like bitcoin carry out verified transactions without knowing the identities of the senders and recipients?

The answer comes in so-called “blind signatures,” and you’ll learn how they operate and how they’re used in real-world situations like voting and cryptocurrency transactions today.

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What Is It Exactly Then?

David Chaum, a pioneer in cryptography and privacy protection technologies and the inventor of digital currency, proposed blind signatures in 1982.

They use RSA and other public-key digital signature methods.

The RSA system ensures communication between two parties by encrypting the message to be broadcast across a channel at the source and decrypting it on reception. Using a digital signature provides the information’s security (authentication of origin, integrity, and non-repudiation).

Blind signatures’ principal goal is to get the signer to sign the message without exposing the content of the communication. This is accomplished by masking or blinding the message’s content before signing it.

In the form of a conventional digital signature, the resultant blind signature may be publicly validated with the original unblinded message.

How Do Blind Signatures Work?

Every time a transaction is made with electronic money and payment is made, all information is entered into a database, according to David Chaum, infringing on our privacy rights.

As a result, using a “blind signature” to hide or blind the content in a message.

David Chaum cites the voting method, which is based on envelopes lined with carbon paper, to illustrate how a blind signature works. This is how the system works:

  • A voter includes a finished anonymized ticket in a specific envelope coated with carbon paper and pre-printed on the exterior with the voter’s credentials.
  • An official checks the credentials and signs the envelope, carbon paper transferring his signature to the ballot inside.
  • The voter receives the package once it has been signed and then transfers the marked ballot to a new plain, unmarked envelope.
  • The signer is blind to the message’s content, but a third party may check the signature and verify that it is legitimate within the limitations of the underlying signature technique.

One of the most common applications for blind signatures has been electronic voting.

Belgium, Brazil, Estonia, the United States, the Philippines, India, and Venezuela are the only nations that have legalized electronic voting.

In Bitcoin Transactions, Blind Signatures Are Used

One of the goals of cryptocurrencies is to build a payment mechanism that protects its customers’ anonymity.

In 1988, David Chaum wrote “The Dining Cryptographers Problem: Unconditional Sender and Recipient Untraceability,” where “public key” notions were explored for the first time.

To comprehend blind signatures, you must first grasp public key cryptography and what cryptographic signatures are.

The public key in public-key cryptography is made up of a random string of numbers deduced from another arbitrary string called the private key. The public key may be determined using the private key. However, if we have the public key, generating the private key is very difficult.

A secret communication may be created between two people A and B, using this sort of encryption, as long as they only disclose their public keys and keep their private keys private.


A blind signature is a digital signature in which the content of a communication is hidden before it is signed in the realm of cryptography. The blind signature is distinguished because it is connected to the encrypted data and the original unencrypted data. This preserves the anonymity and privacy of all users doing digital transactions.