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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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Can a 1 byte difference in AES 128 bit keys make huge difference in output?

If we take some randomly generated key of AES-128 and we change any random 1 byte of that 16 byte key, will this make huge difference in the AES cipher text generated over same input string? Does ...
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1answer
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Are EdDSA algorithms encoded by ASN.1 DER standards?

Is it required, or widely practiced to encode a EdDSA signature as a ASN.1 Sequence? Why or why not? How should you encode a EdDSA signature? I cannot find mention of DER or ASN in the EdDSA RFC. ...
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Yarrow and weak cryptographic keys on macOS

Given that macOS uses Yarrow as a PRNG, and Yarrow is only capable of 160 bit outputs (/dev/random on macOS is actually Yarrow) are keys generated on macOS weaker than Linux? Even BSD has switched to ...
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Encrypt UDP packet with time-generated encryption key

I'd like you to help me solve a dilemma of mine. I am currently building a home automation from scratch for my next house. The basic gist of it is that I will send UDP packets over a local network. ...
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1answer
306 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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AES encryption question

If we consider the generation of keys as $$\begin{aligned} K_0 &= E_K(IV); \\ K_{i+1} &= E_{K_i}(A) \end{aligned}$$ Where A is a block of zeroes, and the ciphertext blocks are computed as ...
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IVs in WEP encryption

First, I'm pretty new to the world of encryption. As I understand it, in WEP, the plaintext and CRC are XOR'd with the IV and the key (or more accurately, the key/stream, which is produced by a pseudo-...
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Purpose of key evolution?

When generating and exchanging keys, what is the purpose of performing key evolution after public key exchange + authenticated encryption?
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1answer
128 views

AES reverse Rijndael key schedule with decryption round keys

I want to get the original encryption key (32 byte) of AES 256 (CBC) implementation. The implementation has the values of the inversed round keys values hard coded into the decryption function. I ...
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0answers
59 views

Are there a way to progress or age key pairs

I am searching for a way to make the noise X pattern fully forward secret. The X pattern is a way to encrypted and authenticated messages. As a building block to achieve this I started pondering if ...
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Differences between the terms “pre-master secret”, “master secret”, “private key”, and “shared secret”?

Both crypto.SE and security.SE have excellent Q&As about how TLS generates session keys (I have linked some at the bottom). In reading these threads I'm having troubles with terminology since the ...
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1answer
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Encrypt multiple RSA keys with same passphrase

I have to create and store a bunch of RSA key pairs with openssl. The private keys will be encrypted with the aes256 option and a very long, random password. Would it be safe to use the same password ...
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1answer
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LoRaWAN 1.0.2 Session Key Security

I am reading about LoRaWAN 1.0.2 specification. For the confidentiality and integrity of the comunication the protocol generate two session keys, the NwkSKey and the AppSKey (part 6.2.5 of the ...
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1answer
69 views

Do Carmichael's and Euler's totient functions in RSA generate the same keys?

Starting with the same primes $p$ and $q$ to generate $n=pq$, will Carmichael's totient function and Euler's totient function give the same public key ($e,n$) and private key ($d,n$) in RSA encryption?...
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Using the same RSA keypair to sign and encrypt

The RSA signature operation is basically the same as encrypting with the private key. In particular, both operations use the same kind of keys. Is it safe to use the same RSA keypair both for ...
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Choosing which is public vs private key

When I calculate two RSA keys, what if anything, would make any difference which I call the public vs which I call the private key?
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Picking 'e' for RSA encryption

What is the reason behind picking either $3$ or $2^{16}+1$ for generating the public key in RSA?
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4answers
2k views

Can a book cipher be cracked without key?

Book cipher works this way : Choose a reference book. For each word find its position in the book. replace each word by its coordinates (ie: 2,3,4 = page 2, 3rd line, 4th word). How would somebody ...
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1answer
692 views

Private and Public Keys

I have a very basic understanding of encryption and the encapsulation process, but for the life of me I can't grasp how public keys and private keys work, how they're made, and how they're exchanged. ...
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63 views

What are the separate single DES keys from a triple DES key?

Suppose my 192 bit triple DES key (in hex) is 0123456789ABCDEFFEDCBA987654321089ABCDEF01234567 What are the keys for the separate single DES operations? In this ...
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3answers
584 views

Why does OpenSSL differentiate between PSS and non-PSS for private key generation?

RSA-PSS private keys The following command will generate an RSA-PSS private key: ...
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1answer
117 views

What is the Risk of Rotating Keys

This may be a difficult question So, $C_1$ = AES-GCM($k_1$, nonce, message) where nonce = HMAC(key,message). $C_2$ = AES-CBC($k_2$, iv, $C_1$). Now, a security breach occurs. The adversary obtains ...
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1answer
36 views

How to prevent Public Key from being replaced entirely?

I am using RSA to sign my license file using Microsoft CNG API. I am signing the license file and sending the file with the <...
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Acceptable points of failure when applying encryption in an application [closed]

I am working an a Windows application that will encrypt and decrypt files using AES Encryption. The 32 byte key which is diversified and derived using a ATSHA204 unique serial number and some addition ...
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5answers
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Why don’t all AES encryption tools produce the same key from the same password?

Alice and Bob meet regularly. They have agreed face-to-face a 128 bit password which they want use to encrypt/decrypt emails written between them. They decide to use 256-bit AES. Alice wrote her ...
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2answers
539 views

Guidelines for cryptographic key generation

I was wondering whether you know can point me to some general (basic) principles/guidelines one should follow for generating cryptographic keys? I have looked at NIST 800-133, but was hoping for some ...
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How to find at least one private key from a large list of compressed public keys secp256k1

Not long ago I saw a discussion on the Bitcoin Talk forum: https://bitcointalk.org/index.php?topic=5060735.msg50736695#msg50736695 Please give advice and working methods? Is it possible to find at ...
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Minimal secure index of quasi-cyclic codes for code-based cryptography

It is well-known that keys (generator matrices) of code-based cryptography are very large for its practical usage. To reduce them scientists propose to use families of quasi-cyclic codes. I remind ...
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68 views

Is it possible to recover the key to a decrypted file? [duplicate]

Is it possible to recover the key to a decrypted file if you have the initialization vector and it uses RijndaelManaged in CBC mode? If so how? The file I want to recover the key from is a xml that ...
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2answers
71 views

How to understand Authenticated Key Exchange?

I am reading some articles about Key Exchange. I know classic key exchange,such as Diffie-Hellman key Exchange. This type algorithm is vulnerable to man-in-the-middle attack. However, When using ...
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1answer
76 views

Euler's totient function and Carmichael's totient function in RSA [duplicate]

I'm a high school student taking IB and I'm doing my EE on Maths, more specifically on the effectiveness of Euler's totient function and Carmichael's totient function in RSA. Am I right in thinking ...
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2answers
48 views

cryptographically signed streaming data

On a high level the question is: how does one cryptographically sign streaming data? Here is the context: a number of people are continuously streaming data to me the data is public and does not ...
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2answers
190 views

Can Pseudorandom values be used as secure keys?

I want to derive $n$ keys from a master key. I pick a master key $mk$ and use pseudo-random function (PRF) to generate $n$ pseudo-random values, $v_i=PRF(mk,i)$ where $1\leq i \leq n$. Next, I use ...
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If 1 can be a random number in Diffie-Hellman Algorithm

I've done some calculations and Diffie-Hellman Algorithm worked for all chosen random numbers except $1$. In the description of the algorithm, I can't find information that the random number has to be ...
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1answer
90 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) ...
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1answer
710 views

How is key rotation defined?

I'm aware that it's advisable to rotate cryptographic keys periodically. HKDF accepts high-entropy input (IKM - Input Key Material), and expands it to an arbitrary length. It also accepts a salt, ...
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1answer
265 views

Can not use big prime number for pair of key of RSA Algorithm [closed]

I'm new to cryptography. I have a binary image with 64x64 pixel in size. I perform an encryption to the image using RSA Algorithm. I wanna ask something bothering me, why can I not use big prime ...
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1answer
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Encryption: am I doing it right?

I'm trying to get a per-user encryption key scheme off the ground and need some validation from wiser crypto pros. Consider the following procedure: User provides registration information to include ...
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1answer
101 views

How complex must round constants be to resist slide attacks?

A key schedule that generates round keys by XORing a round constant with the key is linear and can be vulnerable to related key attacks, but let's ignore that for now. Constants are necessary to avoid ...
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1answer
39 views

Private key not used in a signature scheme

I'm trying to understand the following signature scheme (Camenisch-Lysanskaya): Key generation: $n = pq$ special RSA modulus, $a, b, c \in QR_n$. $PK = (n, a, b, c), SK = p$. Signing algorithm: $m$ ...
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1answer
46 views

How to multiply two Public Keys in Elliptic Curve in Go

I am working on a messaging client similar to Signal. I am stuck on implementing Tripartite Diffie-Hellman handshake in which three DH exchanges are combined to authenticate both parties and produce ...
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1answer
153 views

Why derive keys from a master key instead of generating random keys?

I noticed AWS KMS generates encryption keys based off of a master key, using a key derivation function (HKDF). What's the practical advantage of deriving keys based on a master key? Isn't it simpler ...
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1answer
77 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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2answers
144 views

How to generate a good symmetric secret key

I would like to generate a good secret key, that later will be used to encrypt data symmetrically. I am not sure how to generate a good secret key. I use Linux, I am not sure which sources of ...
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4answers
64k views

How to find modulus from a RSA public key?

I am studying the RSA cryptosystem. The public key consists of $(n, e)$, the modulus (product of two large primes), and the encryption exponent. I want to separate the modulus $n$ and exponent $e$. A ...
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2answers
277 views

How is EC key encoded in PKCS#8?

I just started working with certificates and signatures. For an application I write I need a key pair for ECDSA signatures, using the elliptic curve secp384r1 (aka NIST P-384). I produced such a key ...
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Problem in generation of keys in KP-ABE

In KP-ABE the owner encrypts the message using attributes say a'. The Attribute authority(AA) designs an access structure and implants that access structure in keys generated by AA for the user. So, ...
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1answer
160 views

Is there a feasible way to generate an RSA key manually the same way as it is for an ECC one?

In elliptic curves, a private key is just a random number, and one relatively small compared to other crypto systems (256 bits for ECC vs 4096 bits for RSA for example). Suppose I don't trust ...
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39 views

Aes brute force when part of data known [duplicate]

I have buffer of 16 bytes that encrypt with AES 128 cbc with IV =000000......(all IV is 0) I have the encrypted buffer, and I know 7 bytes from 16 bytes before the encryption , I dont know the key . ...
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1answer
132 views

What is the difference between static and dynamic tokens?

First, what is the difference between hardware and software tokens? Tokens are "what you have" for example a car key or a chipcard. This would be (I think) hardware tokens? But what are software ...