Questions tagged [pgp]
The OpenPGP encrypted data format (RFC 4880), and its implementations PGP and GnuPG.
252
questions
5
votes
1
answer
2k
views
Binary format of encrypted PGP private key?
Short Version of the Question:
I would like to remove any predictable information from an encrypted private keys binary representation. Does anyone have a hint where the binary format for encrypted ...
- 153
2
votes
1
answer
62
views
Older key as PGP subkey?
Currently I have a 2048-bit PGP key. Suppose I create a new 4096-bit key. Can I add that old key as a subkey of this new one?
2
votes
3
answers
233
views
Is PGP's way of maintaining email security optimal? [duplicate]
I read a book called "computer networking: A top-down approach". It talked about how PGP creates an email message between Alice and Bob to maintain confidentiality, integrity, and authenticity. Let me ...
- 359
4
votes
1
answer
454
views
Is there a way to turn a PGP key into its semi-prime counterpart?
From my understanding of PGP keys they use the RSA algorithms to encrypt/decrypt messages. So, I know that the RSA algorithms use a semi-prime number to encrypt/decrypt messages. So, what I was ...
- 77
9
votes
3
answers
2k
views
Why does OpenPGP encryption produce different ciphertexts from the same plain text?
With the same plain text to be encrypted and the same public key, OpenPGP tends to produce a different ciphertext every time I run the encryption operation. Why is this?
- 101
3
votes
1
answer
2k
views
Different kind of PGP keys or IDs, how to interpret them?
When people say "Here's my PGP key", they tend to come up with all sorts of different stuff.
Sometimes they provide an 8-digit hexadecimal number, which seems to be a key ID (although I'm not sure).
...
- 1,387
6
votes
2
answers
3k
views
Why is padding the plaintext with a random string before encryption worse than OAEP / PKCS#7?
I'm reading about OAEP / PKCS padding used for PGP to turn deterministic algorithms like RSA from deterministic encryption to probabilistic encryption (randomness in the resulting output). That way ...
- 663
0
votes
1
answer
514
views
Chosen Ciphertext Attack on the Public Key in PGP
In Secrets & Lies (2000), Schneier describes a chosen ciphertext attack on the public key under PGP:
"Since RSA and ElGamal are malleable, known changes can be made to the symmetric key that is ...
- 155
4
votes
1
answer
850
views
Is a chosen ciphertext attack on PGP still possible?
In a paper from 2002 (pdf), Jallad et al describe a chosen ciphertext attack on PGP by taking advantage of the CFB mode that the block ciphers use under PGP. It's quite a devastating attack.
Is this ...
- 155
1
vote
1
answer
316
views
Private key can't be traced (GPG)?
I am very new to cryptography. I was reading about GPG/PGP Basics when a doubt arose:
As per my understanding, everyone knows the algorithm (from GPG) with which I generated my key pair. If I show my ...
- 121
2
votes
1
answer
248
views
Is this cascading encryption, and is my security weakened as a result?
I'm trying to understand what is, and what is not, considered cascading encryption. All of the posts and conversations I've read over the past few days discourage the practice, including this article. ...
- 21
10
votes
1
answer
3k
views
Why does "gpg --export-secret-keys" ask for a password? [closed]
What is it about the architecture of GPG that requires me to enter the password of the secret key when I export it with "gpg --export-secret-keys"?
I would expect that gpg can just copy the relevant ...
- 329
5
votes
1
answer
1k
views
Can gnupg master key decrypt something encrypted with subkey?
When creating gpg subkeys, the master key signs and certifies that a subkey belongs to that master. That's ok, but, can master key decrypt something encrypted by a subkey? I guess no, but I want to be ...
8
votes
1
answer
10k
views
How to generate fingerprint for PGP public key
I would like to know how to generate a fingerprint for an openPGP public key.
To be clear, I'm interested in how the fingerprint is generated. I'm aware that I can get the fingerprint with a ...
- 83
2
votes
1
answer
376
views
Using e-ID Number for Encryption and Digital Signing
I want to use e-ID number for performing Encryption/Decryption and Digital Signing - and in order to do so, I've opted a PGP-oriented approach which goes a bit like this.
Generating PGP key-pair ...
- 21
0
votes
1
answer
4k
views
How long can a RSA public key be?
If I create an RSA of 4096 bits, what would be the range of the length in bytes of the public key in DER format?
Also, will the private key always be exactly 4096 bits (512 bytes)? Does the public ...
- 125
3
votes
1
answer
3k
views
Perfect Forward Secrecy in PGP/asynchronous email
Looking at the RFC for PGP email/asynchronous chat with PFS here https://datatracker.ietf.org/doc/html/draft-brown-pgp-pfs-03 can anyone tell me why the following scheme is no good?
Alice and Bob ...
- 31
3
votes
2
answers
2k
views
Why does GPG ciphertext length differ with fixed plaintext length?
Thank you for your reply.
Based on your inputs. I was investigated further, find details below
Step 1) Input string for encryption is UUID format
Input data = c0c6f311-a793-4d65-9374-1c0e45f5382c
...
- 31
8
votes
1
answer
4k
views
gpg --gen-random quality level: is higher "better"?
The GNU Privacy Guard manual pages have this to say about using the gpg --gen-random 0|1|2 count command:
Emit count random bytes of the given quality level 0, 1 ...
- 333
1
vote
0
answers
870
views
Simplest way for strong cryptography in chat [closed]
I am a beginner in cryptography and I am interested for several weeks on this for my chat application.
Basically, it is a centralized model. All messages are stored and potentially visible by ...
- 21
2
votes
2
answers
175
views
Initializing PGP keys by one side
I am using a PGP method to encrypt and decrypt messages shared between users A and B.
Upon the start of a message exchange is the initialization of the public and secret keys by both Users.
Lets say ...
- 227
7
votes
1
answer
233
views
Why does GnuPG save an array of remainders when generating prime numbers?
In looking at GPG's gen_prime() function, found within the cyphers/primegen.c file of ...
2
votes
1
answer
171
views
Encryption on the cloud with versioning
Can file-versioning, which is available for instance in Dropdox, weaken the security of encrypted files if someone is able to see two or more snapshots of the ciphertext at different times?
To be ...
- 101
6
votes
1
answer
3k
views
ECDH and ECDSA in PGP with known public key
How are used ECDH and ECDSA in combination with public key ? Usually these methods are used for establish a secret themselves, ...
- 113
5
votes
1
answer
435
views
OpenPGP Public-Key algorithm
What means when pgpdump shows this kind of algorithm in the Public-Key Encrypted Session Key Packet?
...
- 113
2
votes
1
answer
475
views
Possible to detect if a message is PGP encrypted/signed (ciphertext)
Let's say I have a text field somewhere (i.e. an interactive user submitted text field on a PHP script, or a console application. Basically anything that accepts user input.)
How can I detect if said ...
- 21
7
votes
2
answers
4k
views
Why must we generate the signature before any compression being done at PGP?
I have done some research on PGP and I found out there are of two reasons why we must generate the signature before doing any compression. Yet, I am not sure I really understand them both.
One ...
1
vote
0
answers
186
views
Details related to the ZIP algorithm used in PGP message encryption? [closed]
I am very new to PGP. PGP encryption works with hash function, asymmetric encryption, symmetric encryption and a zip algorithm (LZ77). What I know is that the zip algorithm is used to reduce the ...
3
votes
1
answer
632
views
Implementing forward secrecy in OpenPGP with public key authentication
I am trying to consider the feasibility of implementing an encrypted file sharing system, which both provides forward secrecy but also allows public key verification. I am stuck on the marriage ...
- 133
5
votes
1
answer
1k
views
Generating PGP key *without* random generator? (using fixed input only)
I understand why in general, a strong random generator or source of entropy is used when generating PGP keys.
However, I have a use case where I want to generate PGP keys deterministically, i.e. ...
- 1,387
0
votes
3
answers
232
views
Some doubts about GnuPG
I've reading on GPG since yesterday and I have a doubt: the whole system of double key encryption does make sense but it looks to me like either way you are compromising something in terms of security....
- 11
0
votes
2
answers
1k
views
How to decrypt a PGP message with only the two primes and the public exponent?
I'm trying to decrypt a PGP Message that is encrypted with an RSA key, but I only have this information:
Public exponent:
65537
Prime 1: ...
- 103
3
votes
1
answer
21k
views
PGP public RSA key format
I have been trying to use Go (I could post the code, but I think I posted enough already...) to generate a PGP RSA key. However every time I try to encrypt something with it, something fails. However, ...
- 131
0
votes
1
answer
466
views
Is it a bad idea to use PGP encryption for structured/predictable data?
I'm working on an app and need to encrypt some structured data. The data will be turned into a string form (JSON) before getting encrypted.
The data format I'm using will always start with a ...
- 285
3
votes
2
answers
8k
views
PGP digital signature vs SHA256 HMAC Comparison
First let me admit that I am not a mathematician or a cryptographer.
I am responsible for assisting in making a recommendation on a project that is consolidating payment processes within a company's ...
- 45
5
votes
1
answer
4k
views
How do revocation certificates work in PGP?
I've already read how to build and upload them, but I'm wondering how revocation certificates work, what informations they hold and so on.
Suppose my private key is compromised, but I have a ...
- 223
7
votes
1
answer
61k
views
How to decrypt a '.enc' file that has been encrypted with RSA using a public key? [closed]
While solving a CTF challenge online, I came across a situation where I needed to decrypt a '.enc' file that has been encrypted using someone's public key. The ...
- 687
1
vote
1
answer
688
views
How are RSA and ElGamal compatible in PGP?
I'm starting to play with PGP and I don't understand how if your key pair is RSA
you can encrypt a message for someone whose key is for example ElGamal.
How does the asymmetric key exchange work if ...
- 13
0
votes
1
answer
8k
views
How do you break encryption on a message? [closed]
This may seem like a simple question, but I have just started studying cryptography and I can't seem to find any information on this at all. I am trying to write a "simple" encrypted messenger using ...
- 3
6
votes
2
answers
2k
views
Signing Files vs. Signing File Hashes
What are the security pitfalls that may occur by signing a list of file hashes, versus signing individual files?
In short, the security trade-offs between:
...
- 161
0
votes
1
answer
930
views
How exactly to extract information base 10 from a PGP RSA key pair?
I think I understand the mathematics of RSA ok. I'm not so computer savvy though. How, exactly, can I extract $n$, $e$, $d$, $p$ and $q$ from a PGP RSA public key pair? Is there like a converter ...
- 121
0
votes
1
answer
1k
views
GPG & Mcrypt - difference?
in short I'm learning GUI programming in python and thought it could be interesting to make a small GUI for symmetric encryption. Not being mad/mathematical/experienced (take your pick) enough to try ...
- 35
6
votes
2
answers
810
views
Can you fake messages from recorded message-history?
Lets assume Eve has a lot of PGP conversation with Alice and records all those messages. Bob is also regularly communicating with PGP with Alice.
If Bob doesn't care about not having a signature ...
- 207
6
votes
1
answer
7k
views
What characters are valid in PGP encrypted and signed messages?
What characters may be present in a PGP encrypted message or a PGP signature? For example, do encrypted messages only use the Roman alphabet + some numbers and symbols? Can the character set be ...
- 163
5
votes
2
answers
705
views
PGP String-to-Key specifiers
I've been reading through the PGP Standard and here I'm a little confused. This section is discussing converting string data to a session key. I'm confused about the paragraph in bold. First off, what ...
- 51
-1
votes
1
answer
2k
views
PGP message integrity : How can receiver of an email check the integrity using the sender's public key?
PGP message integrity:
Basically, only private key can decrypt message encrypted with public key. But in the message integrity service in PGP does the reverse, where the Hash of the message if ...
- 9
3
votes
1
answer
144
views
Familiar key signing over video call
Say that a friend of mine and I have both generated new PGP keys, and we want to use a video call to verify each other's new keys because we live on opposite sides of the planet. While we could both ...
- 133
1
vote
0
answers
94
views
Want to use ECC but am clueless [closed]
First off, I'm not an experienced cryptography or computer person, please bear with me. I have some basic experiences with PGP software though (not much of a redemption huh?). I have some data that I'...
- 11
8
votes
2
answers
7k
views
How do I create a short signature? (e.g. less than 100 bytes)
I want to put information into a QR code and have it signed so that the authenticity of the information can be verified. But QR codes have limited storage capacity and when I used e.g. gpg I get ...
- 225
6
votes
1
answer
544
views
Difference RSA keypair creation openSSL and openPGP?
Creating a 2048bits RSA keypair I figured that doing this using
openssl takes as an input 32bytes of "randomness" from ...
- 405