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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How is the private key kept secret in digital signatures?

A digital signature is verified using an algorithm that takes three inputs: the message, the digital signature (message encrypted with private key)* and the public key. If the public key is used to ...
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78 views

How does a Sign tool work?

My basic understanding of how a sign tool works is: Load the zip-file (may be exe, jar, ddl, apk, etc.) which has to be signed to its memory (cache memory of the sign tool). Verify it and unzip the ...
2
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0answers
10 views

Signtool validation fails when signing and validating are done in different machines

I am signing an exe from a machine using a cer file. Then when I validate the EXE using the signtool.exe from the same machine, it succeeds. But when I try to validate it using the same .cer installed ...
55
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8answers
8k views

Proving creation time/date of a screenshot

I have to produce a screenshot of a web page, and want to make sure others will know without any doubt that this screenshot has been produced today. That is, I would like to embed today's date in the ...
2
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2answers
51 views

Asymmetric key encryption that can have a public decryption key, but encryption key cannot be computed from that [duplicate]

Is there a way where I can distribute a public decryption key, but the encryption key cannot be computed from that key, so that anyone who reads one of my encrypted message, he/she can be quite sure ...
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0answers
14 views

Digital Signature on a Passive RFID tag with small-ish memory constraints

I'm pretty new to the crypto and security worlds and I'm looking for some guidance. Briefly, my project involves Widgets (physical items that need to be authenticated) and Gadgets (physical machines ...
17
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2answers
4k views

Does my PGP key really need to match the e-mail address for which I'll be using it?

In considering whether or not I want to join the big web o' trust and put my keys on a key server, I got to thinking about how it would affect my e-mail address' exposure. I generally try to keep my ...
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1answer
113 views

What scenarios really benefit from signed JWTs?

UPDATE: I have concluded my research on this problem and posted a lengthy blog entry explaining my findings: The Unspoken Vulnerability of JWTs. I explain how the big push to use JWTs for local ...
0
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2answers
36 views

Can an RSA signature be changed given the public key?

If I were to post on a forum (with potentially malicious administrators) my public RSA key and a small string of text that was signed with the corresponding private key, could someone with access to ...
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1answer
45 views

What issues exist in generating a signed, paper-based PGP message stored by a hostile organisation?

I have recently been the victim of having my medical record tampered with by the organisation holding it. Under state law I have a legal right to submit information to be included in my medical record,...
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1answer
126 views

Algorithms for transaction authentication

It's unclear to me how transaction signing and transaction authentication work. Industrial solutions use both symmetric and asymmetric algorithms to compute the signature. What does RSA add the ...
3
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2answers
79 views

Useless 2FA in case of inside attacker

Suppose a server-side signing scenario, where user keys are generated in a HSM and exported to a database, encrypted with a symmetric key derived from a user password and HSM's master key. To sign, ...
1
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2answers
49 views

What are the technical implementation differences between signature-based scanning and heuristic-based scanning?

Signature-based scanning works by comparing something to a database. So does this basically amount to scanning a file x for string foobar? I know heuristic-based scanning can detect new threats that ...
2
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2answers
418 views

End to end security for REST services, any emerging standards?

I work with integration in the healthcare sector, where end-to-end security is important. We integrate with numerous SOAP services, and use the WS-security features to encrypt and sign requests and ...
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2answers
58 views

How does digital signature algorithms work in a private / public key environment?

From the Wikipedia page on the subject, I get, on a theoretical level, how the process of encrypting and decripting a message works. The article states that: In a public-key encryption system, any ...
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0answers
72 views

Alternate SSH authenticate

I was doing a little bit of research on how SSH actually authenticates a user and different things. And I came across a document which nicely explains how SSH authentication works which is something ...
2
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3answers
140 views

Are there any systems to mitigate the risk of losing a Signing Key?

I want to design a system that hinges on ECDSA. All messages are signed using the algorithm, and this is used to prevent spoofing. However, if a user were to somehow lose control of their key, they ...
66
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3answers
12k views

Why shouldn't I bring a computer to a key-signing party?

I'm looking at the event description for the key-signing party at an upcoming BSD conference, and it's mentioned that I shouldn't bring my computer in to the event: Things to bring no ...
0
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1answer
32 views

git file signing with eID

Background story; government issues new IDs (eID) which can hold certificates and you can sign documents with it, using card reader and some software that signs document itself (while I do research ...
0
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1answer
45 views

Why is CBC-MAC insecure for variable length input?

Can anyone explain why CBC-MAC is not secure for variable length message? I read many books, but there are still some confusion. Like the highlighted parts in following pictures Slide 32: Slide 33:...
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1answer
117 views

Digitally signing a document with your public/private keypair without certificates?

I have generated a private/public key pair using gpg. Can I use this key pair to digitally sign a PDF without a digital certificate, but to still have the signature integrated into the PDF, instead ...
0
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1answer
105 views

Why would I need to use the PRIVATE key to verify a file signature?

I use JavaScript to open CAPICOM store to choose certificate. After that I export selected certificate, public key and private key of that certificate and put them in three hidden fields. var ...
3
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2answers
61 views

What are the benefits to adding a bitcoin blockhash UID notation to one's OpenPGP key?

Example: Notation data: blockhash@bitcoin.org 000000000000000011d9f6931e65f814c6f3b221736b0c45f25e0365a3d156fa As seen here: https://sks-keyservers.net/pks/lookup?op=vindex&search=...
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3answers
63 views

Does digital signature really ensure data integrity?

Suppose attacker knows public-key of sender. He can make his own private key derived from public-key of sender. Then he can alter message and sign it with his private key. Probably I'm missing the ...
2
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0answers
38 views

Algorithm to generate (and verify) string of 4 quad alpha numeric code

I am writing a system, for which I need to generate unique transaction numbers (which can be verified by myself). I want to use something similar to that used by credit cards, where a string of the ...
42
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2answers
10k views

Why are hand-written signatures still so commonly used?

Why are hand-written signatures still so commonly used? Can they actually prove anything? Two assumptions: If anyone wants to forge my signature I'm sure they will be able to do it. Even my own ...
14
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6answers
23k views

What does “key with length of x bits” mean?

I'd like to know what it means to say "the cryptosystem C uses keys with a length of x bits". I do not understand what the bits length means... doesn't it depend on the encoding? The same word encodes ...
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1answer
143 views

Code signing certificate validation by Java

Despite several web search, I can’t find an accurate explanation on code signing certificate validation by Java. I am wondering if the code signing certificate (the “final cert”) must already be in ...
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1answer
32 views

Can a 3rd party validate the origin of an HTTPS session?

I'm wondering if HTTPS can be used as proof that a server reported an answer. If I understand correctly, the initial handshake is for HTTPS is the only time that the public/private key of the server ...
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1answer
55 views

Value of hash in digital signature

I'm hashing using SHA 256 and signing a payload with a private key.The payload does not contain any password and would be HTTP(S) POSTed to server side. The payload contains some dynamic and constant ...
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0answers
33 views

Altering assembly without affecting digital signature

I have discovered a software crack where the license check assembly (.NET) has been altered but the digital signature and the strong name are both still perfectly intact. Strong naming is easy to ...
2
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1answer
116 views

What is the difference between a digital signature and whole message encryption?

I am newbie in information security I am trying to understand the difference between a digital signature and encryption of a message. Lets consider simple example of email message. I understand how ...
0
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1answer
57 views

How to verify the signature of DHE_RSA server parameters (TLS 1.2)?

By reading the TLS 1.2 specs I have been able to manually decrypt/encrypt pretty much all the steps of a TLS connection (DHE_RSA_AES_CBC_128_SHA cipher suite). One of things I am missing is how to ...
2
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2answers
531 views

PKCS#1-1.5 encoding - is there a reason to use 00 in block type?

For encryption block looking like this: EB = 00 || BT || PS || 00 || Data where BT - block type and PS - padding string, I've read that we use three types of BT - 00, 01, 02. Now, since 00 and 01 are ...
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0answers
16 views

Digital Signature - PKCS#7 Response

I have a long xml-style string which looks like this: MIILhMIILhAY......H9WH9W Task given to me is to digitally sign a pdf document. Is there a tool (like jdk keytool or openssl etc) which I can use ...
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2answers
66 views

Signing Double Submit Cookies, where the value is a pseudo random string and a signature of it. Is this more secure?

I'm not sure if I am describing something that has already been proposed. If not, I would like to coin this "Signed Double Submit Cookies" as a method to improve the Double Submit Cookies technique ...
0
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1answer
32 views

Hashing and signing partial data in payload

I'm hashing and signing part of a payload prior to HTTP Posting from a mobile device to server side. The payload contains of about 7 data elements and only 3 of them are hashed/signed using a private ...
0
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1answer
37 views

How secure is it to bundle unencrypted private key and a CSR into PKCS12 certificate?

I want to create a self-signed certificate to digitally sign my documents. I want to do so using my existing key pair, but to accomplish this I'd have to export my private key unencrypted into a file, ...
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0answers
40 views

Create a signed file from the detached signature and the clear text file content

Assuming I have the following: data.txt data.ps7 (the detached signature) Can I generate the bundled signed file ? Any example would be great, using C#, Java or openssl or any other tool ?
7
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2answers
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How do systems protect against a stolen code-signing certificate after the certificate expires?

Imagine this scenario: 1st December 2014 - a certificate is stolen and used to sign malware with 2014-12-01 timestamp. 15th December 2014 - the certificate is revoked. Malware will be prevented from ...
4
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2answers
71 views

Signature that can only be verified by author and recipient - without pre-shared key

Desiderata: Alice wants to send a message to Bob for him to keep and to be able to refer to, such that Bob can be certain that the message came from Alice and was not tampered with. Alice also ...
0
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1answer
34 views

Verify a key was signed by another key

I began using GPG4Win/Kleopatra, the GNU Privacy Guard implementation for Windows. More recently I wanted to verify a download of Qubes OS, for which a guide is offered here. They describe a master ...
3
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2answers
76 views

Signing the Recovery Partition

Do any computer manufacturers sign (DSA, or just publishing a hash) their recovery partitions so that I can be sure that these bits are authentic? I'd like to buy a second-hand computer and reduce ...
1
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1answer
56 views

Why timestamping chain is better than “code signature” chain?

Timestamping is recommended as the way to prolong signature validity after its certificate expiration date. One just need to add new timestamp signature before previous timestamp is expired. But what'...
0
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0answers
52 views

Few questions about verifying a DLL signature?

i have few questions about verifying a file's certificate. The use case is as follows: i have a DLL file that contains a resource i need. I'm signing the file with a code-signing certificate, and ...
6
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1answer
136 views

Why would I sign my git commits with a GPG key when I already use an SSH key to authenticate myself when I push?

Simply put, I am wondering why would one need to sign one's commits with a GPG key when contributing to GitHub when one's already required to provide an SSH public key?
4
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3answers
84 views

Are document signature services violating any rule by exposing PII over clear email?

A company sent me a document to sign via CudaSign, I did. As soon as I completed the transaction, I got a PDF over email with the document attached. The document includes my SSN. I assume, the ...
3
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0answers
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Is there a cryptographically secure way to verify the date of a process? [duplicate]

I have a few git repositories of content that will be updated constantly over the next decade. At some point down the road I anticipate being asked to prove that the content was actually in the state ...
3
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1answer
47 views

How to acquire DNSSEC root trust anchor from IANA?

I want to establish trust in a DNSSEC record. I found, that it can be done $ dig +sigchase +trusted-key=./root.key @8.8.8.8 eesti.ee root.key could be obtained with $ dig . DNSKEY @8.8.8.8 | grep -...
21
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3answers
4k views

Does OpenPGP key expiration add to security?

I've created a new OpenPGP key to sign a software package in a source repository with an expiration date three years from now. It seemed like a good security measure, because if the key is compromised ...