Frequently asked questions about sproof, digital documents and blockchain.

In sproof, each change of your profile is represented by an event. Multiple events can then be embedded into a single transaction. In order to submit your events to the blockchain you need to digitally sign them with your private key. Therefore, you need to enter your passphrase before your events can be sent to the blockchain. Once the transaction is submitted, it will take up to 10 minutes before your changes are available in sproof.

sproof can be built on top of any blockchain. The public version of sproof uses the public Ethereum blockchain.

In sproof, you can choose where you want to store your private key. There are two options:

  • On the sproof server: We securely store your private key for you. For that, we encrypt your private key with a passphrase of your choice.
  • On your own computer: You can download your private key from our web app. You can create your private key also locally on your device and only store your public key on our servers. We then have no access to your private key.

The sproof-code is a synonym for mnemonic and used to generate your private key.

The sproof testnet allows testing sproof for free. You can setup a free profile and discover the potentials of sproof at no cost. You can always switch to the mainnet for productive use. The testnet provides full access to all sproof features and uses the same interfaces and API as the sproof mainnet. Please note, however, that the sproof testnet uses the Ethereum testnet blockchain, may be subject to frequent changes and does not provide the quality and security guarantees of the mainnet. Never use the testnet for productive use. Developers can use the testnet for setting up and testing their processes before going productive on the mainnet.

The sproof explorer shows all information which is publicly stored on the blockchain and in ipfs. The explorer can be used to view all sproof profiles, documents, transactions and events. Additionally, the explorer provides the functionality to verify if a document, e.g., a PDF file issued via the sproof network.

The password is used to secure your sproof account. We do not store passwords in plaintext, but we can send you a link to reset your password. In order to commit transactions to the blockchain you need a private key. This key is stored encrypted and protected by your passphrase. sproof is never in possession of your passphrase and has no access to your private key. If you forget your passphrase we can not reset it for you and you can only create a new passphrase by knowing the old one. The sproof-code is a synonym for mnemonic and is used to generate your private key.

See, recursion.

An event represents a single action of a sproof profile. Each sproof profile needs at least one event: the profile create event. For each additional step, e.g, profile update, document registration or revokation, an additional event is created. To increase the performance and to reduce costs we register multiple events within a single blockchain transaction, which is signed by the private key of the profile.

A Web of Trust (WoT) is a network of confirmations. Each member of a WoT is allowed to confirm each other user. This means for sproof, that each profile can confirm all other profiles. You can confirm profiles of entities you know and trust. Similarly, the strength of your profile increases if you collect confirmations from other profiles.

A transaction is the only way to append data to a blockchain and is usually signed with the senders private key. In case the transaction is valid, it becomes part of a new blockchain block.

A public key is used in asymmetric cryptosystems and is needed to verify digital signatures or to encrypt data. There always exists a cryptographically linked private key to a public key.

In sproof we link the public key of a user to a profile. A profile consists of a name, image and a description. It is also possible to add and confirm a website. Additionally, a profile can collect confirmation from other profiles to build a Web of Trust.

A private key is needed to create digital signatures, encrypt or decrypt data. There always exist a cryptographically linked public key to a private key. For blockchain applications, e.g., sproof, the private key is your secret to add or update your data. If you lose your private key, you do not have access anymore. The private key can be encrpyted with a passphrase.

A passphrase is a password which protects your private key. You can only change your passphrase if you know the old one. If you forgot your passphrase we can not reset it for you. This is to protect your private key from unauthorized access.

A nonce is a random number which should only be used once in cryptographic operations.

A mnemonic is a sentence or a collection of words. In sproof we use menemonic to generate your private key.

A hash is a numerical value with a fixed length which can be deterministically created from an input of arbitrary length. A hash is usually created from a hash function. Cryptographically secure hash functions are needed for digital signatures, blockchains and many more applications.

A document can be any file in any format. Most commonly, documents are PDF files.

A digital signature is a cryptographical scheme to verify the authenticity and integrity of digital data or documents and also to check the identity of the signer. In sproof the signer is represented by a profile. With a sproof profile you can register and digitally sign documents and data.

A blockchain is a decentralized, append-only database. Blockchains group transactions into blocks and use cryptographic building blocks such as public and private keys and hash functions. sproof uses a blockchain to immutably store hash references to information about your profile and registered or revoked documents.

In a blockchain, blocks are used to group and append transactions within the globally consistent database. New blocks are (usually) appended at the end of the chain only and hash references are used to connect each block to the previous block.

In case your private key gets leaked, you have two options. First, you can revoke your profile and create a new one including a new private key. Second, if you registered an offline (cold storage) private key to your profile you can update your online private key with the offline key.

If you loose or forget your private key, we have no way to recover your profile. You are the only one, who has access to it. In the settings page you can create a new key.

A passphrase is a kind of password which encrypts protects your private key. So if you loose your passphrase you need to create a new private key.

The advantages of sproof are digitally signed unforgable documents. sproof is decentralized, scalable and transparent and can be easily integrated into existing applications. Learn more about the advantages here.

Yes. A developer API for collecting signatures with sproof sign is available here.

No. Any company or organization can use sproof sign.

Yes. The sproof sign online signature service is provided free of charge. There is, however, a premium and an enterprise service with additional features.

No. We use the power of already established public blockchains.

It is easy to integrate sproof in existing applications. Please follow our guide on the developers site to learn more about the integration.

Digital signing can be done by either using qualified digital signatures (e.g., “Handysignatur”) or by using unqualified digital signatures.

Once a signature has been submitted or all contacts have signed the document, you can download the signatures separately or in a single file.

Documents can be signed either with digital handwritten signatures or qualified signatures, such as the Austrian public signature service (Handysignatur).

No. A login is not required, but optional in order to use additional features.

Yes. We store all your documents within the EU and you can delete if no longer used. This is done in accordance with the GDPR.

sproof sign also supports encrypted PDF documents. When inviting contacts to sign an encrypted PDF, you will have to share the password over a separate and secure channel.

Yes, automated reminders can be sent.

sproof services only store and sign a hash reference of your data. As long as you do not choose to store your document publicly you may register sensitive documents, as they are not publicly accessible via sproof.

Short answer. No, you can’t.

Long answer: Blockchains are append-only databases. Once a transaction has become part of the blockchain it is practically impossible to delete that data. sproof only stores hash references in the blockchain and without the original data it is impossible to learn anything about the document. However, you may choose to store documents publicly. In this case, it is not possible to delete these documents. You may revoke documents, but that only adds a flag in that documents history without changing the original entry.

No. Signatures are collected in parallel for improved speed and performance.

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