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Questions tagged [digital-signature]

A digital signature (not to be confused with a digital certificate) is an electronic signature that is used to authenticate the identity of a message sender or document signer, and usually to ensure that the original message/document content is unchanged (document integrity).

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What is the difference between PKCS#7 and CADES, PADES and XADES?

I am newbie in PKI. For signing a pdf documents we are free to consider each pkcs#7 format or PADES format. If I have some misunderstandings, please turn it on for me.
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45 views

How to protect file integrity and history containing counters

I would like to create a solution that would sign the data and will have a increasing counter so I can track the number of signatures. One of the requirement is to have an increasing order of ...
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31 views

Cracking signing and HOTP blackboxes

If there are these blackboxes, both are using algorithms which are considered secure yet: Blackbox will sign any message, no limit for messages to be signed. Blackbox will generate 8‐digit HOTP code ...
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1answer
25 views

Server to Server Communication RSA or x509 Certificate

I want to build Server (My) to Server (Other Client parties) web service and I want to add security layer for client verification. Do I need to force clients to create x509 Certificates or RSA key ...
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2answers
102 views

What's the point of a digital certificate for which no private key exists?

I am only using digital certificates to sign documents, and my understanding is that the correct flow is the following: create a private key (e.g. using openssl) create CSR using the previously ...
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1answer
130 views

Why is validating the integrity of the plaintext necessary in addition to validating the integrity of the cipher text?

Reading the iOS Security Guide's description of the iMessage encryption protocol I'm trying to figure out why they included a mechanism for verifying the integrity of the plaintext as well as ...
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1answer
77 views

Is there a file system allowing read-only access enforced by cryptography

Is there a file system standard (like LUKS) that allows anyone who can plug in the hard drive to read files, but requires a passphrase to modify or write? For example, I can do something similar by ...
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1answer
63 views

How do I create a detached plain text signature?

If I use gpg --detach-sig file, then I get a small file.sig, but it is not plain text, so this is not useful if you wish to send the signature in a plain text format. If I use gpg --clearsign file, ...
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How to understand: digital key encryption, public key decryption in Digital Signature? [duplicate]

How to understand: the sender in the digital signature encrypts the message digest private key and sends it to the receiver. The receiver then decrypts the public key. We say that asymmetric ...
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3answers
181 views

How secure is using MD5 for signature

Generally speaking, MD5 is considered as broken for secure usage these days, but I came across a signature design using MD5 many times recently in my company. The detail shows as following: T = text, ...
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5 views

blind signature [migrated]

Reading this paper, I have some questions about blind signatures What is the meaning for unlinkability of blind signatures? I searched wiki, but still cannot understand exactly. In blind signatures (...
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1answer
68 views

Using same algorithm for signing and encrypting a message

If we use the same algorithm to encrypt and sign a message, what can happen if the message is intercepted and read by a third party?
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1answer
55 views

What does “probabilistic algorithm with random tape” mean?

I am new to the study of cryptography, and when reading papers they often mention that "probabilistic algorithm G with random tape w ...". What does it mean by "random tape w"? I mean why it does is ...
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1answer
38 views

Asymmetric Encryption + Signature workflow

Let´s say that Alice wants to send an encrypted message that only Bob can read, plus confirm that Alice is the person that wrote that message. What is the procedure that will take place? When I see ...
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51 views

Is it possible to build an ASiC container out of a file and its timestamp token?

If I have: A file, X The RFC3161 timestamp token of X Are these sufficient to build a (single file) ASiC container with the file and the timestamp? In other words, is the timestamp included in the ...
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1answer
61 views

Signing and encrypting with pairs of keys based on discrete algorithms

In case I've generated pair of keys (public and private) for RSA, I'm able to use it both for signing and encrypting. Is the same statement true also for pairs of keys based on discrete algorithms?
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Verify PKCS#7 (CMS) detached signature with timestamp with OpenSSL

I have a PKCS#7 (i.e., CMS) detached signature of a file that is signed by my signing certificate and then timestamp signed by a TSA that is all generated by an application we wrote. I would like to ...
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Is it possible to save a verifiable log of a TLS session? [duplicate]

Here's an example situation: I download a file from some server over https, but I also save a "log" of the TLS communication. Later, that file is removed from the server and nobody believes me when I ...
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2answers
110 views

Is GPG a kind of digital signature?

So I've been using GPG since I've touched Linux&LibreOffice, but I only knew that's its a signature, for identifying the work is created by me. But soon I've been touching some law questions and ...
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Proving that a certain site had given page at certain time [duplicate]

Lets someone opens https://foo.com and saves the page using "save page as". Is there any way to prove later that the locally saved files have not been altered assuming that we trust the server public ...
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1answer
83 views

SHA1 signature in a SAML request

I'm currently looking at the security of a KeyCloak implementation, which again uses SAML 2.0 identity provider. I'm not too familiar with SAML, but during the authentication, the sent SAMLRequest ...
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2answers
77 views

How to sign a text in a way, so it can not be altered or split in parts unacknowledged

Given, I want to create a document (text-only for the sake of this question) and give it to someone I do not trust. I am not allowed to publish it myself. It's probably not going to be published (...
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57 views

Why is digital signature enforcement on webservers not common practice?

Why is it that server admins do not code sign the contents of their webservers (all php, css, js, etc.) and have Apache / NGINX / whatever server software refuse to execute or serve any code / ...
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1answer
56 views

Signing JWTs with server's SSL/TLS certificate

I have a server that needs to sign JWTs asymmetrically. I can either generate a new public/private keypair or re-use my keypair used for my server certificate. Is there any concern about re-using my ...
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2answers
66 views

Signing webhooks with asymmetric keys

I want to sign webhooks from my web service with a JSON Web Signature (part of JWT standard), ideally using asymmetric keys (so, using RSA or elliptic curve cryptography). What is the recommended or ...
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1answer
67 views

What are the risks in returning digitally signed payloads over an insecure HTTP connection?

Let's say I own a service and a client needs me (for the sake of this question) to provide an endpoint over HTTP (not HTTPS) that doesn't use cryptographically secure authentication. Further, there's ...
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1answer
33 views

hmac based request signature for verification

say i want an application to integrate my services & need some way of verifying requests from that application, i have an integration key, and a shared secret, i can generate a generate a ...
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111 views

In what important ways can a digital signature be invalid?

I am trying to write some code to verify that a digitally signed file came from my company. I was horrified to stumble across this deeply buried answer on Stack Overflow, an out-of-left-field ...
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1answer
70 views

Does the key size have an effect of the size of the public key and signature

If I have a 2048-bit RSA and a 4096-bit RSA key is my signature and public key smaller when I use a 2048-bit key vs a 4096-bit one ? (In bytes)
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2answers
53 views

RSA signature security with short keys

RSA keys with the size of 1024 aren’t considered to be safe anymore. Does this also apply if you use this key for signing only? Can a signature be faked easily with a short key length?
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1answer
102 views

Asymmetric public-key cryptography: can either key be used to encrypt or decrypt?

Key exchange describes a public key encrypting plaintext and the private key decrypting, while in digital signatures the reverse is true where the private key is used to encrypt a hash that the ...
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1answer
62 views

Signature verification against custom CA [duplicate]

I need to (write a program to) verify signature in a (bunch of) signed XML files. NOTE: I am dealing with XML files signed according to 'http://www.w3.org/TR/2001/REC-xml-c14n-20010315', not just ...
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1answer
124 views

Signing and timestamping implementation

I am writing a software that records and stores data files. I want to digitally sign and time stamp these files so that I can assure that it's Contemporaneous and Attributable (to comply with 21 CFR ...
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1answer
156 views

Is it possible to fake ECDSA signatures?

Recently, I came across a reddit post claiming it was easy to mutate bitcoin signatures to generate message/signature pairs. https://www.reddit.com/r/btc/comments/9xpivk/...
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3answers
214 views

What if somebody sends me genuine certificate that they do not own? [closed]

I just started learning about the digital certificates, its architecture and how it works internally. What will happen if someone sends me a genuine certificate for authentication which does not ...
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1answer
75 views

Are all fields of the PE certificate directory hashed during authenticode signing?

In a Windows portable executable (PE) file the certificate directory points to an offset to a WIN_CERTIFICATE structure. My understanding is that while the field is named bCertificate, it actually ...
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5answers
7k views

What does “signing” a file really mean?

I'm a bit new to security and trying to get the concepts properly. I'm wondering what exactly "signing" a file (a certificate, an apk file, or something else) means? Do we sign the whole file so ...
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1answer
184 views

How can I use 'safe' Elliptic Curve algorithms in .Net Core?

I'm looking to build my own digital signature operations into a program I'm writing, and the nuances of cryptography are a bit beyond me. According to this website the NIST/NSA algorithms (P-224, P-...
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1answer
51 views

Public Key Crypto - sign Bob's name into Alice's message or encrypt Alice's name

I was reading Defective Sign & Encrypt in S/MIME,  PKCS#7, MOSS, PEM, PGP, and XML and in section 5.1  Naming Repairs By signing Bob's name into her message, Alice explicitly identifies him ...
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1answer
117 views

Signal Protocol: How is identity exchanged if a key exchange hasn't happened yet?

On Signal's blog they mention that keys for accessing your profile are exchanged normally with your contacts using the Signal Protocol just like messages are (implying they are already contacts and ...
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3answers
143 views

Is it possible to use “cryptographic hash function” for “digital signature”?

I understand that a cryptographic hash function is a function that generates a fixed size random string for an arbitrary input. However, is it possible to use a cryptographic hash function for ...
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0answers
65 views

Working with Security Metadata in APK file

According to this Blog post, Google has added a Security Metadata on top of an APK to verify that it was originally distributed by Google Play. More specifically it adds APK Signing Block to the APK ...
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2answers
44 views

Allow setting both server URL and public key - security hole?

We have a licensing system where our software, a commercial product we sell to people, contacts our licensing server when starting to get an OK to run. It contacts our licensing URL and passes up an ...
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2answers
158 views

Is there any list of vulnerabilities and their signatures?

I am looking for a list of known vulnerabilities and their signatures. Is there any publicly available list of security vulnerabilities and their signatures? NVD (NATIONAL VULNERABILITY DATABASE) ...
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1answer
109 views

Explain how a digital signature is employed for providing a proof of authenticity (not integrity!) of a file [closed]

Explain how a digital signature is employed for providing a proof of authenticity (not integrity!) of a file.
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2answers
297 views

Does a File's Checksum Change after it is Digitally Signed?

From my understanding, when you digitally sign a file, it changes that file's checksum because they are bundled together. Example of what I mean: file1.txt only contains the letter 'd' and the ...
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2answers
101 views

Why digital signatures needs different algorithm

Why digital signatures uses algorithms such as DSA, ECDSA or RSA-PSS, and not just the RSA algorithm to encrypt the message hash with the private key? Is the choice more security or performance ...
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1answer
96 views

Concepts of PKI Encryption and Digital Signature Authentication [duplicate]

I am trying to understand how SSL uses PKI and Digital Signature authentication to ensure secure and verified communications. I've read various sources online and from what I can tell the basic ...
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2answers
81 views

What happens when the timestamper's certificate expires?

What happens when the timestampers certificate expires? If the code is now untrusted, can it be re-stamped without re-signing? If not, what good does this timestamp do me if my cert is valid until the ...
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2answers
59 views

How to overcome slow process of creating and verifying digital signature?

From what I understood is the digital signature is a long process and have following steps: Hashing the Message Plain Text using a well-known (public) hashing algorithm. Encrypting it with sender's (...