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5

The standard way to do this is with a hash list. That is, you would hash each of the messages $m_i$ to produce a hash $h_i = H(m_i)$, and then combine all the hashes and hash them to obtain a master hash $h = H(h_0 \| h_1 \| h_2 \| \dots \| h_n)$. Finally, you can e.g. digitally sign the master hash to prove that the hash, and by extension all the ...

5

Although I can't see any immediate weaknesses, I also don't see how it adds significant value over DSA (while being significantly slower). It claims to be based on two hard problems, discrete log and factoring. However, it doesn't give any particular proof that if you could forge signatures, you can solve both problems. It also doesn't look particularly ...

3

I'm trying to get my head around how the crypto solves this problem. It doesn't. You need to trust the platform you use to do the signing. For instance, my bank has replaced the "signature" generation device that I previously used with one that displays the actual transaction, so I don't have to trust the information on the computer screen that much.

2

It is outside the scope of TLS and must be arranged out of band. Raw public keys come without any signatures and cannot be verified without additional knowledge. Section 1 of the RFC mentions a few ways how they might be verified in some situations. They all amount to receiving the public key through some other authenticated channel. The TLS client ...

2

ECKEY object may contain: Group Private key Public key Both Group and Private key are needed to be able to calculate signature. It is most convenient to use generic ECKEY object (from API perspective), as it easy to e.g. convert between commonly used PKCS#8 PEM encoded EC private keys and ECKEY objects, and because just a BIGNUM would not be sufficient. ...

2

The short answer is that there's no link between your physical signature and any cryptographic signature. Indeed, from the high-level description of how DocuSign works and their security manifesto there's no reason to believe that any cryptography goes into the signature process itself. Note that “signature” is an overloaded word. In this post, I will refer ...

1

The premise that you don't need to split the messages before encryption is incorrect. Given that there are schemes giving (partial) message recovery for signing also means that that premise is incorrect as well. The message doesn't need to be split up before signing (which includes hashing), so that premise, finally, is also incorrect. Encryption operation, ...

1

The web site of https://ellipter.com says, they are using encryption.

1

A few things. First of all, MD5 is broken, and no longer suitable for cryptographic purposes. Instead, prefer newer algorithms, like those from the SHA-2 family (SHA-256, SHA-512, etc). Second, the term "signature" in cryptography is defined more narrowly than you would expect. It specifically refers to situations where there is a public key (the ...

1

First, there is no way that crypto can keep an attacker from manipulating the data that is shown to the user. to prevent this, you have to trust some part of your hardware, at least the screen that views the data and some chip inside that can do some crypto. Moreover, digital signatures alone will not solve this problem as the merely capture signing a ...

1

Actually, it has not really to do with zero-knowledge. From any public-coin three move identification scheme you can derive a secure signature scheme (in the random oracle model) using what is called the Fiat-Shamir heuristic. Many of these protocols represent honest-verifier zero-knowledge proofs (like the Schnorr, GQ etc. protocols). Now, every such ...

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