The common method to provide non-repudiation in the context of digital communications or storage is Digital Signatures , a more powerful tool that provides non-repudiation in a publicly verifiable manner. Message Authentication Codes MAC , useful when the communicating parties have arranged to use a shared secret that they both possess, does not give non-repudiation.
A misconception is that encrypting, per se, provides authentication "If the message decrypts properly then it is authentic" - Wrong! MAC can be subject to several types of attacks, like: message reordering, block substitution, block repetition, Thus just providing message integrity and authentication, but not non-repudiation. To achieve non-repudiation one must trust a service a certificate generated by a trusted third party TTP called certificate authority CA which prevents an entity from denying previous commitments or actions e.
Note that the goal is not to achieve confidentiality: in both cases MAC or digital signature , one simply appends a tag to the otherwise plaintext, visible message. If confidentiality is also required, then an encryption scheme can be combined with the digital signature, or some form of authenticated encryption could be used. If the key used to digitally sign a message is not properly safeguarded by the original owner, digital forgery can occur. To mitigate the risk of people repudiating their own signatures, the standard approach is to involve a trusted third party.
The two most common TTPs are forensic analysts and notaries. A forensic analyst specializing in handwriting can compare some signature to a known valid signature and assess its legitimacy. A notary is a witness who verifies an individual's identity by checking other credentials and affixing their certification that the person signing is who they claim to be.
A notary provides the extra benefit of maintaining independent logs of their transactions, complete with the types of credentials checked, and another signature that can be verified by the forensic analyst. This double security makes notaries the preferred form of verification. For digital information, the most commonly employed TTP is a certificate authority , which issues public key certificates. A public key certificate can be used by anyone to verify digital signatures without a shared secret between the signer and the verifier.
The role of the certificate authority is to authoritatively state to whom the certificate belongs, meaning that this person or entity possesses the corresponding private key. However, a digital signature is forensically identical in both legitimate and forged uses. Someone who possesses the private key can create a valid digital signature. That means that to use the card for encryption and digital signatures, a person needs the personal identification number PIN code necessary to unlock it.
From Wikipedia, the free encyclopedia. ISBN S2CID Linux Bible. Wireless Personal Communications. Nothing will ever stop someone going to court to dispute a signature. Even if I apply a digital signature myself, fully consciously, I might find myself disadvantaged somehow, and seek remedy in the legal process. Perhaps my digital signature software didn't properly render the transaction, or was simply buggy? Perhaps the contract was unconscionable? Perhaps I was coerced or under duress?
You've nailed it. Regulatory filings for a company in India have to be signed digitally by the company's director. The procedure for doing this is utterly farcical: My outsourced agency sends me a digital signature file as an email attachment. I double-click it and run it on my PC. Then I sign the bunch of PDF files and upload them to the regulator's website. I asked the agency what would happen if the said email were to go to someone else, would that someone else be able to run the software on their PC and digitally sign the PDFs as me?
They told me, "Oh, we're a chartered secretary firm, sorry we can't answer your IT questions"! As a result, I've never felt comfortable with digital signatures. If ever I get disadvantaged on my regulatory filings, I'll describe this farcical procedure to challenge non-repudiation in a court of law.
Todd Carroll. Nir Laznik. Emily Harris. Pavlo Farb. Blog article. News in your inbox For Finextra's free daily newsletter, breaking news and flashes and weekly job board. Sign Up. External what does this mean? This content is provided by an external author without editing by Finextra.
It expresses the views and opinions of the author. Let's Get Back to Productive Work: The recent and very public departure of Mike Hearn from Bitcoin has temporarily distracted the broader Blockchain community from the three problems that the Fintech community is trying to solve.
These are: What are the principles that govern the alleviation of distrust among partially rational actors with competing economic interests, thus permitting them to exchange value otherwise known as economic activity. How do we prevent the pension of Average Joe and Jane Doe from disappearing into the abyss of the layers upon layers of fees levied by the stack of intermediaries in the investment process otherwise known as disintermediation.
Meditate and Witness the Profound Truth Beyond Reasonable Doubt The harmonizing principle of law in the civilised world is For example: Default: If Jane Doe defaults on her debt obligations, I should be able to claim the money back through an orderly legal process and not have to send a pack of strong men to Jane's home as some banks in emerging markets actually do! Fraud: If Joe sells the house that actually belongs to Jane, Jane and the buyer Jade should be able to sue Joe and be made whole.
Value Disputes: If Jane sells something to Joe at an unreasonable price, there should be a legal mechanism for Joe to dispute the price in the real world. Transaction Disputes: If Joe says he never gave the money to Joe, there should be a way to show that at least the data shows he did, or someone hacked in and did it as him. Sanctions: International law is not about fairness.
It's about balance of power. Money Laundering: If Joe gets naughty and steals in taxes, he should have to apply extreme effort and creativity before he can use that money to buy that swanky villa in Vegas. The Demands of Non-Repudiability: Non repudiability of Digital Identity requires the following attributes: Tamper proof storage: Naughty Joe can't overwrite Jane's digital passport and stick his name, date of birth, photo or address in there, for example.
Strong Encryption: Joe can see Jane's data only if he is authorised by some kind of a legal contract e. Digital Signatures: Jane must do i love the term Data Permissioning: Joe can only see the data they are authorised to see and not Jane's social security number for example unless Jane shall non-repudiably bless it upon him In other words, if I Joe's trading billions of dollars, you want a lot stronger physical evidence than if poor Joe's posting on instagram Blockchain for Blockchain Now if these principles themselves point to something very blockchainy Report abuse.
A Finextra member 21 January, , 0 likes Some interesting points in there Ajit. Any thoughts on how ZeroCash might fit into the current financial system Stephen Wilson - Lockstep Group - Sydney 24 June, , 0 likes What a lot of strident, almost religious nonsense. Non repudiation is non-sensical. Get real people. Join the discussion.
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Non-repudiation means that. crptocurrencyupdates.com › articles. In this context, non-repudiation refers to the ability to ensure that a party to a contract or a communication must accept the authenticity of their signature.