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Questions tagged [keys]

Private and secret keys consists of secret information used as input to various kinds of cryptographic algorithms such as encryption, signature and MAC to select the concrete transformation done by the algorithm.

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What is the key to these encrypted messages? [on hold]

So I'm trying to reverse engineer a lock system that consists of a chip reader and a control unit. There are only two devices on this network, the reader which reads a rfid like chip and the control ...
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1answer
59 views

Looking for AES CBC algorithm example [closed]

That sound strange but I don't find in network psudoCode/c#/c/python clear code that show how AES CBC working. I will be happy to see code like that / movie with examples with hex byte to see how it ...
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PCI DSS requirement 3.5.3

3.5.3 Store secret and private keys used to encrypt/decrypt cardholder data in one (or more) of the following forms at all times: ............ As at least two full-length key components or key shares, ...
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Why would one split HKDF output into multiple parts instead of expanding it multiple times

Reading the implementation details of Signal's approach on double ratchet algorithm I noticed the following key derivation procedure for using AES-CBC with HMAC: HKDF is used (...) to generate 80 ...
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0answers
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GlobalSign cert in Trusted root for Google Services shows Sha1. Security postures

"GlobalSign" certificate in Trusted Root Certification Authorities for Google Services shows Sha1. Security postures are different than just 2-3 yr ago. At my home, router bought 2016, networked; ...
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Private key management in memory [migrated]

I'm a developer who's working on a networking protocol that includes encryption. It doesn't really matter, but just for the sake of context I'll mention that I'm using libsodium crypto library. Now ...
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2answers
322 views

How much extra security does key wrapping provide?

Wikipedia says: Key Wrap. Key Wrap constructions are a class of symmetric encryption algorithms designed to encapsulate (encrypt) cryptographic key material. The Key Wrap algorithms are intended ...
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1answer
33 views

ED25519 Child Key Derivation

Let's say I generate a keypair for a user with go's ed25519 package: pub, private := ed25519.GenerateKey(nil) And I want to generate additional child keys as ...
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1answer
33 views

Attack vector difference when not allowing repetitions in BIP-39

We are using a 12-word scheme BIP-39 mnenemonic key generating scheme that creates an entropy of 128-bit that is then used to generate a seed that in turn derives a private key for the user. It ...
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1answer
125 views

Key Entropy meaning Help

Can anyone help me understand key entropy the mathematics behind it and the uses for it? I understand most of it but I just want to understand what does $\log 2$ do like if I do. $\log 128 / \log 2 = ...
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1answer
64 views

Does the public key and private key for WhatsApp only remain within a WhatsApp account

The world of cryptography is starting to really intrigue me admittedly. I initially hated it because it looked too hard Mathematically but now it looks cool :) Got a good question for the experts and ...
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1answer
113 views

How to find fixed points for DES weak keys

Can someone explain me this please I am a bit confused? It's from a texbook I am reading (block cipher companion) it says that: each weak key has $2^{32}$ fixed points $m$ where $\operatorname{...
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1answer
50 views

Does repeated xoring of the (same) key K lower the entropy of K?

If a symmetric encryption key $K$ has been generated by some recommended (NIST for example) RBG then we should have a key with high entropy. But if we xor other bit-strings (e.g. IVs, other keys, etc....
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0answers
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Asymmetrical encryption with multiple sufficient key-pairs [duplicate]

I have the following requirement: There are N public/private RSA key pairs. The encrypted data must be decryptable by any of the private keys alone, but not by any other key. For encryption, the ...
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5answers
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Is a PRG more costly than AES or any other encryption standard?

I know that there are many encryption standards that take a key and sometimes an IV, and produces a cipher-text (the most prominent one is AES). These standards usually involve many rounds of addition ...
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0answers
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Asyncronous Rachet tree: How user movability is handled is the Rachet tree being recreated?

As I have read the latest state of art in group key agreement is the Asyncronous Rachet Tree. But in applications like IRC that exists high user movability (users join in ans leave the room). Is ...
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1answer
79 views

Find $F(2x)$ from $F(x) = a^x \bmod p$

Given $F(x) = a^x \bmod p$, where $a$ is a primitive root of $p$, Is it possible to work out what $F(2x)$ or $F(3x)$, etc if you know what $F(x)$ is but not $x$. If you use $F(x)$ then $F(2x)$, etc ...
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1answer
32 views

mDP kay agreement protocol where z's are found on the step where the common key is generated?

Whilst I was studying the mDP protocol I came across into the following step: Group Key agreement: Each $U_i$ checks whether $z_1 \bigoplus ... \bigoplus z_n = 0$ and whether all signatures $\...
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0answers
61 views

Signal Sender Keys: Why it works and which is the common key at the end?

As I has read upon "WhatsUp Encryption Overview" when a client receives a sender message then it performs the following actions: Decomposes Sender Message to ...
7
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1answer
95 views

HMAC-SHA-512 with a 256-bit key

I am implementing hmac-sha-512 in an integrated system. However, one subsystem is only supports the use of 256-bit keys. I read in https://tools.ietf.org/html/rfc4868 that: However, note that [...
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2answers
38 views

Maximum number of possible keys for a fixed-length password?

I'm reviewing some information and possibilities regarding key space size following a unique password requirement, as it were. This particular requirement is a fixed-length password of 12 characters, ...
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2answers
89 views

Two working decipher keys giving various, valid results for one ciphered message - is it possible?

Let's assume following scenario: There's a ciphered message. Two decipher keys (let's name them A and B) are known. Message deciphered with key A gives valid result - normal text but with no secret ...
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0answers
27 views

GPG Sub Key Renewal Questions

Last year, I followed this guide to create two GnuPG Smart Cards; one card with the Primary Key and the other card with the Sub-keys. I noticed that the sub keys were close to expiring so I renewed ...
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1answer
68 views

What happens at this part in the key schedule of a Speck…?

I am trying to figure out the process behind the Speck block cipher. I understand how XOR works (Exclusive-or) when you take 2 strings of bits and you want to XOR them together. However, in the key ...
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1answer
95 views

Keys-space for a restricted substitution cipher

How can one calculate the key-space for a restricted substitution cipher? A restricted substitution cipher is one where no letter is assigned to itself. For an alphabet with 26 letters how many keys ...
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1answer
67 views

Basic Vigenere Cipher

I'm taking my first cryptography course and having trouble deciphering some Vigenere encrypted text. I was able to crack the first one: I'm having difficulty with the other two. I think the ...
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1answer
43 views

Signal/TextSecure multiparty Chat. Does the protocol transmits a symmetric key?

As I look over the TexSecures specifications for multi-party chat I have noticed this. Also as far as I understood in TextSecure (now known as Signal) the minimal steps required to do a secure ...
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0answers
62 views

Need help decyphering message [closed]

THEIR DIFFERENCE WILL REMAIN, LONG AFTER THEY ARE DEAD Dear Friend, IV IV 12 8 14 - 19 14 18 9 13 IV I C C 9 17 IV 17 12 IV 8 14 IV 7 F 14 IV 7 19 D IV 12 15 F 19 E IV 8 17 IV 7 12 15 F 19 13 17 9 E ...
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0answers
26 views

Nature of risk(s) from KeeChallenge XML file stored in cloud at Onedrive

As a noob user of KeePass2 on Windows desktop and Keypass2Android on my phone, supplemented by YubiKey Neo configured for hmac-sha1 challenge response, I noticed that Keepass2Android appears to store ...
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1answer
49 views

Does it make sense to have long SSH Key with shorter Passphrase?

If we encrypt our data with a longer SSH key which is protected by a shorter passphrase (with a decent entropy), then the limiting factor is entropy of the passphrase. So why do we use a longer key at ...
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0answers
34 views

Is there hierarchical key generation that completely tolerates leakage?

Is there a hierarchical key construction algorithm that achieves forward/backward privacy with any (unlimited) leakage of private non-master keys? What I mean is that if there's an unbounded number ...
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1answer
60 views

How do i manage encryption keys with a cloud provider?

I would like to provision services from a Software as a Service (SaaS) provider. This is multitenant environment (multiple companies will be using a single instance of the application, with a single ...
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0answers
44 views

Is it possible to successfully encrypt/decrypt in DUKPT using different sized BDKs?

We are having our P2PE Solution validated against the PCI P2PE standard. We currently use a TDEA 2-key based BDK, and IPEK in both the encryption and decryption environments. ANSI X9.24-1 (2009) ...
2
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1answer
104 views

Getting a Keeloq manufacturer key

I have seen a lot of articles and research papers about breaking the Keeloq algorithm. My understanding is that the hardest part is getting the 64 bit manufacturer key. Some methods use crypto-...
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2answers
103 views

Does AES use different keys for each block of plaintext?

If you have 4 16-byte blocks of plaintext to encrypt does each block have a different 128 bit original key? Or do they all use the same?
2
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1answer
52 views

The “openssl genrsa” command only generates a private key?

The command : openssl genrsa -out RootCA.key 4096 generates a single file named RootCA.key. When I open the file, it only contains the private key. Then ...
2
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1answer
51 views

Revoke a GPG key using previously generated revoke certificate after renewd (change expiration date)

I have few sub-questions Do secret keys get expired, or just the public key gets expired? Do I have to back up the master sec key each time I renew it? For an ...
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0answers
72 views

Where shoul I store private/public keys and how should I share it?

I'm new in terms of encryption and I have to encrypt the data between two Java Spring applications, one have serves as MVC framework and other as Web Service, I'm implementing an asymmetric encryption ...
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1answer
37 views

Only remember part and format of BitLocker password [closed]

I am a complete novice to the field, however I made the mistake of locking my Macbook bootcamp partition with a bitlocker password which I cannot remember entirely. There isn't much irreplaceable ...
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1answer
33 views

How should short term keys (keys stored in RAM or volatile memory) be described by PKCS#11?

How are short term keys usually implemented by PKCS#11? Is the proper way to distinguish between keys that are more temporary/stored in volatile memory and those stored in non-volatile memory to ...
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1answer
166 views

How to extract a BIP39 mnemonic from an Ed25519 encrypted private key?

How to generate a BIP39 mnemonic from an Ed25519 (Ed25519+libsodium, with 8 for salt, 48 for key plus 32 bytes) encrypted private key? I have an Ed25519 encrypted private key (for which I know the ...
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2answers
56 views

How is it possible for a VPN connection to be created through the ISP?

I will be theoretical here. Let's say you want to create a VPN connection with some VPN provider. You have to agree on some key to encrypt the data. how can you get the key without your ISP knowing it?...
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1answer
37 views

HSMs: Encrypt/Decrypt - But Not Read or Export Key

Can HSMs be configured to store a key, and allow encryption or decryption with said key, but prevent any export or backup of the key itself? We're basically trying to develop a system using ...
2
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1answer
70 views

Ciphertext to different plaintext

Is there any algorithm for generating the same ciphertext from different plaintexts, depending on the key used? This seems similar to Honey Encryption, but I don't need to have every key give ...
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0answers
46 views

JWK vs. raw for key wrapping

Context (TLDR below) So I’m developing an application that uses a high-iteration-count PBKDF2 algorithm to derive a symmetric AES-GCM key from a user-provided (enforced to be reasonably strong) ...
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5answers
84 views

Multiple Encryption - One-Time Pad

It is known that One-Time Pad(OTP)s are theoretically unbreakable but impractical for use because of the size of the key length. But what if multiple encryption is used? Not to encrypt the first ...
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1answer
140 views

Half of any bitcoin (crypto) public key - (public key half) is possible

I found a topic on bitcointalk Public key x and y == Double(Half of the Public key x and y) half any public key is possible how that possible , in crypto there is subtraction and multiplication ...
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1answer
39 views

Is it possible to manage an encrypted dataset for face recognition?

Im in my final year of PhD in computer vision and my supervisor has given me a task that I am not very familiar with. So I am teaching myself homomorphic encryption everyday. This question is mostly ...
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1answer
61 views

Cutting down the size of a long blowfish key

I am reverse engineering a software that uses blowfish for encryption. The target uses an implementation of blowfish that allows arbitrary positive key length with a key size larger than 56 bytes. I ...
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1answer
46 views

How to be sure to retrieve the good key when brute-forcing a cipher?

Imagine the case of the one-time pad. It is proved to be secure because the key could be everything. We have no guarantee that this key or that key was the one used while encrypting our data. ...