Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [signature]

Algorithms and protocols for creating signatures to documents, and verifying such signatures. These are normally asymmetric, for symmetric signatures see [mac].

1446 questions
15
votes
1 answer

Compact digital signature for noisy data

The question asks for a signature scheme, with a public verification procedure, that is tolerant to minor alterations of the signed data during its transmission [possibly in analog form over some noisy channel], where the signature is a small…
fgrieu
  • 140,762
  • 12
  • 307
  • 587
10
votes
3 answers

Is signing a hash instead of the full data considered secure?

I reference object in some of my code in hashes. The signature is itself is another object separate from the one I am signing (for obvious reason). I consider simpler to simply sign the reference to my object (its hash), but I wonder if it is…
Gopoi
  • 230
  • 2
  • 12
9
votes
4 answers

Non-outsourceable digest-free signature scheme

Given a message $M$, I am looking for a signature scheme that does not involve first computing the digest $H(M)$ and then signing $H(M)$. Signature schemes on digests are outsourceable in the sense that the private key holder does not need custody…
Randomblue
  • 512
  • 3
  • 13
7
votes
2 answers

signatures that are verifiably generated by one of several private keys without revealing which one

is there an encryption algorithm that allows to: generate a set of different private keys sign data with those private keys allow to publicly verify that such a signature has been created by ONE of keys in the set without revealing which one it…
matthias_buehlmann
  • 290
  • 1
  • 6
6
votes
2 answers

What is the one-time signature scheme with shortest signature size known?

There are several one-time signature schemes. The original one - Lamport - has very big signature sizes (several kbs). Is there an one-time signature scheme on which relies only on simple assumptions (one-way functions and random oracle), and on…
MaiaVictor
  • 1,345
  • 8
  • 16
6
votes
1 answer

Simple digital signature example with number

I've been looking for a simple which signs a number with some randomly generated key and then verified(decrypts the original number) with the public key, which is generated by the private. All the examples I've found does not feature an example with…
Kirill Kulakov
  • 163
  • 1
  • 1
  • 4
5
votes
2 answers

Isn't code signing just digital signature on code?

I have been trying to understand why code signing is treated or discussed differently from digital signature. Digital signature is signing a hashed BLOB with a private key. When the BLOB is code/software, it is code signing. So, isn't code signing…
Paras Shah
  • 51
  • 1
5
votes
1 answer

Why Random Secret Necessary Almost in all digital Signature Algorithms

I've read some introduction documents about digital signatures, and all they said is Signer calculates a hash of data to be signed. This hash is encrypted with the private key. Verifier reads the document and calculates hash again and compares it…
Ali.G
  • 51
  • 4
5
votes
2 answers

Are there any digital signature algorithms in common use that result in 32-byte signatures?

I don't consider myself to be an expert in this field, so forgive me if there is an obvious answer. I am having a tough time finding an algorithm that can sign data and output a 32-byte signature, that is in common use. Specifically, I'd like to…
RLH
  • 153
  • 6
4
votes
2 answers

Using ePassport with Active/Chip Authentication to sign documents

I'm a complete newby, so please pardon my ignorance when it comes to basic cryptography aspects. My question is whether a biometric passport with Active/Chip Authentication (AA or CA) can be used to generate digital signatures for docs (or rather…
Proto Ukr
  • 153
  • 4
4
votes
0 answers

How many signatures can a signing key (safely) produce

Given an AES key, there is a limit (of about $2^{64}$ blocks) of how much plaintext it is safe to encrypt with the key. Is there a similar limit for how many signatures it is safe to produce with a signing key (such as RSA, DSA, or ECDSA)? (I would…
Martin Bonner supports Monica
  • 266
  • 2
  • 11
4
votes
0 answers

Using cryptography: How to handle this real life situation?

For my class in applied information security I'm asked to find a cryptographic solution to the following problem: The government of country X wants to simplify the process of issuing driving licenses. The idea is that the person do not need to go…
Cristina
  • 124
  • 8
4
votes
1 answer

How does the verification process associated with this signature scheme work?

My cryptology professor asked us to show that while the following signature scheme is conceptually valid, that it is inherently insecure, however, I am not sure how to demonstrate that the associated verification process produces an equality if the…
hodgepodge
  • 43
  • 4
4
votes
2 answers

Very short signatures? (eg: 48bits?)

Our application requires some 'mild' form of 'proof of origin' for the tokens we issue (~200 bytes), however, the value of each is trivial. The requirement is to provide 'tamper resistance' rather than 'unforgeable', to not bloat the token size, and…
Justin Maxwell
  • 41
  • 4
4
votes
1 answer

Signing and verifying message consisting of several parts

Given a message $m$ that consists of several parts. we want to be able to verify individual parts or a combination thereof. The simplest solution is independently signing each part. But since asymmetric signatures are relatively expensive to compute…
NinjaV
  • 83
  • 1
  • 9
1
2 3 4 5 6 7