Questions tagged [key-derivation]

In cryptography, a key derivation function (or KDF) derives one or more secret keys from a secret value such as a master key or other known information such as a password or passphrase using a pseudo-random function. Keyed cryptographic hash functions are popular examples of pseudo-random functions used for key derivation.

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How to choose parameters for Argon2 for password vault

I'm creating a password vault and I'm planning on using Argon2id to derive the master key from the master password. For encryption I'm planning on using XChaCha20 with Poly1305. To be clear: a set of ...
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Using platform-level RNGs for key derivation with hash functions like BLAKE3?

So I've read stack overflow questions like this one. What I'm wondering is a bit more specific though: I'm really liking what I'm seeing with BLAKE3. (I suspect that this hash function is relatively ...
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Why is SKEYSEED derived using the nonce as a key?

In IKEv2, SKEYSEED, which is used to as a seed for generating the rest of the keys, is generated as SKEYSEED = prf(Ni | Nr, g^ir)...
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Is it possible to derive a constant value from different signatures of a private key?

For example perhaps deriving the same PRF from RSA signatures on different messages from a (not known) private key? Struggling to find the proof of why not.
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Security problems if ECDH and ECDSA use the same key [duplicate]

Hy! I want to use an EC key for ECDH and ECDSA too. Using the same key does compromise the security of the key in a cryptographic / mathematical sense? I read a lot in this theme, but I found nothing ...
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Can I use the same key pair for authentication and Diffie-Hellman? [duplicate]

Assume Alice has a key pair $(A, a)$ and Bob has a key pair $(B, b)$, where $A = Ga$ and $B = Gb$. In general, the basic rule of crypto says that we should not use the same key for different ...
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Can I compress $192$ byte key into $16$ or $32$ bytes which can be later used in KDF to recover full key

I have a key $k$ which is $192$ bytes long. Is there a secure way to first compress this key into $16$ or $32$ bytes, but in such a way that later given those $16$ ($32$) bytes I can use a key ...
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For TCG-Opal drives, which password is used to derive KEK?

SEDs use a user password (PIN) to generate KEK by a KDF algorithm. The KEK is then used to encrypt the MEK (where MEK is internally generated in the drive). But TCG-Opal drives have 9 locking-ranges ...
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Good key update algorithms for key evolving schemes

In schemes like SAKE(Symmetric-key Authenticated Key Exchange) , the master keys (used to authenticate parties and generate session keys) are evolving, ie undergo transition $K=update(K)$. What is a ...
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is it safe to do public key to public key derivation with Ed25519?

Deriving a public key from a public key in Ed25519 is possible, some algorithms are available. My question is why there are so few implementations compared to secp256k1 for example. The extra checks ...
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Using XOR to derive a data key for ECIES

I have been thinking about a rather simple enhancement for (EC)IES / RSA-KEM. The scheme would allow you to encrypt data while the calculation of the session / data key can be performed afterwards or ...
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Generate AES key from weak string

I'm trying to generate AES256 key from user input password. The size of the password can be anything from 4 bytes long to 32 bytes long but let's assume it is the smaller one. My API support either : ...
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Any gotchas when deriving a symmetric key from two seeds?

Consider a connection protocol where, after jumping through several other hoops, Alice and Bob know each others' public keys; and they now want to do a RSA-handshake-kind-of-thing to come up with a ...
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What are the randomness requirements for inputs to PBKDF2?

I need to generate one 160-bit HMAC-SHA1 key for each user in my system. Can I use the username as the input to PBKDF2 function to generate the key? Is it safe to use known values like username as ...
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How hard is it to link a hardened BIP32 child public key to it's parent public key?

The BIP32 spec says this in the security section: ...
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How to handle IKEv1 and IKEv2 diffie-hellman shared secret bits length not multiple of 8?

In Cryptographic Algorithm Validation Program for KDF document, here, page 9, it says "If a field size that is not a multiple of 8 bits, the shared secret is represented by a string of bytes that ...
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How to Derive a Child RSA Key Pair from an Existing RSA Key Pair?

I want to understand how, using standard tools like openssl (or similar), to derive a child RSA key pair from an existing RSA key pair. Additionally I would like the derived key to contain a ...
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KDF for generating RSA and ECC keys from a 2048 bit secret

Do KDFs exist for generating RSA and ECC keys from a 2048-bit random secret?
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Are My Answers to This AES Question Correct?

Question I am extremely new to cryptography and AES and so I am not confident that I did this question orrectly. Please can you check my answers and let me know if anything jumps out as incorrect, ...
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KDF options for a ECDH shared secret

the answer to this question suggests that the x-coordinate of an ECDH shared secret is itself usable as an encryption key without apply a KDF.... if so, then what additional security is provided by ...
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Is it necessary to stretch/derive an AES key when I already have enough bytes from a 'cryptographically secure RNG'?

I'm using AES-CBC-256 with PKCS#7 compatible padding. I already have 32 bytes that come from a 'cryptographically secure random number generator'. In this scenario, does it make sense to use PBKDF2 to ...
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Meaning of the term “Key Material”

I am reading specifications from my client that focuses on the topic of security. In these specs, the term key material has appeared many times. I used Google to look for what the term means. ...
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Secure password reset

In my model I use two different keys, one for authentication and the other for the encryption / decryption of the data that the user saves, each derived from the master password with a KDF function. ...
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KDF and salt storage

Regardless of the KDF I will use, let's imagine that I have to generate two keys, one for authentication and the other for encryption (which will always remain on the device that generates it until ...
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Is Argon2id safe from the discovered Argon2i issues?

So far, as I understand it, two ways to reduce the complexity of Argon2i have been found, one of which was fixed in Argon2 1.3, and one of which is still unfixed but is not a practical problem given ...
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Apply HKDF After DIffie-hellman Key Exchange

Im trying to use HKDF after DIffie-hellman key exchange. However, i got stuck on HKDF part. ...
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How to apply a block cipher to (large) packetized communication when packets can get lost/erased?

In light of current events (Zoom getting strong headwinds for using AES-128 in ECB mode), I was wondering what the general approach is to packetized data encryption, where the packet length (UDP for ...
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Computationally expensive key derivation whose difficulty is asymmetric

I am looking for a primitive or a construction that meets the following requirements. Is such a construction (a) theoretically possible, and (b) in existence right now? Given are: a long secret $X$ ...
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How passwords are fed to key derivation functions?

Suppose I want to encrypt data, send it over the network, and decrypt it on the receiver side. I know the elegant way to do this is by using a symmetric key to encrypt the data and an asymmetric key ...
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DHE parameters: which parameters need to be random each time?

In DH key exchange, first, both parties need to agree on a generator $g$ and prime $p$. After that each party computes its key (party A: $g^a \bmod p$) and (party B: $g^b \bmod p$), then they exchange ...
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ChaCha20-Poly1305: Can my salt/pass for a KDF also be the nonce?

I have a PSK. I don't want to use it directly. I want to pass a "salt"/password into a KDF and get a new key for authenticated encryption with ChaCha20-Poly1305 . I need to give the other side the ...
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Using PSK starting a new session, encrypt the new session key with old, or sign a derivative to be used on the old key?

I have two endpoints that go through a middleman. Both have a pre-shared and secure key, 16bytes to be used with ChaCha20-Poly1305. Extremely constrained device. No packet larger than 100 bytes total. ...
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TDES (Triple DES) DUKPT decryption

We have a POS (Ingenico) that uses DES3-CBC encryption using a derived key. It sends encrypted data, and 10 bytes size Key Serial Number (KSN). I tried to use ...
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KDF3 - implementation explanation

An old project that I did not code is using the KDF3 algorithm, but I struggle to find an explanation about the way this key derivation algorithm works. I know that this algorithm is part of the ISO-...
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Is it safe to use a deterministic salt as an input to KDF (Argon2)?

I'm prototyping an app that uses client-side password hashing in order to hide the "real" account password from a server (the server hashes any recieved password anyway, so no plaintext records in the ...
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Derived keys usable by threshold signatures

Suppose there are $n$ members in a $(t,n)$ threshold signature scheme. The global secret key $sk$ is not known to any single party, as the keys are generated distributed. The parties are able to ...
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BIP32 Extended Key to EC Private and Public Key Pair

We are working on an application in Android using Java. In our project, we used to generate EC key pairs (of size 384 bits) using SpongyCastle - an old Android version of Bouncy Castle. The problem ...
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Scrypt cipher - known vulnerabilities and cryptanalysis? [duplicate]

there is a Scrypt cipher which is used for exmaple by some cryptos like LItecoin for their mining algorithm. I never heared of scrypt. I know eg SHA256 which is well analyzed and considered as secure ...
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Multiple random keys vs multiple keys derived from master key

If Alice is going to share a symmetric encryption key and a kmac key with Bob using asymmetric encryption (sign with static key, encrypt with ephemeral keys - an authenticated KEM), what are the ...
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Multiple AES Key Derivation from a master key

I need cryptography advice regarding this issue. Kamus is a service that encrypts secrets for applications running on Kubernetes. When using AES (actually, Rijndael) symmetric encryption, Kamus uses ...
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ZKA Approval Scheme

I'm having hard time finding any resources for ZKA (Zentraler Kreditausschuss Approval) security schematics used by IFSF Part 3-21 Security Standard (https://ifsf.org/documents/ifsf-standards/). ...
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“Safe” or Safest Method for Non-Hardened Key Derivation Functionality

I'm currently working on the development of an unorthodox system in which, ideally, there would be one master key pair, with thousands of keys derived from it. There needs to be a way to prove that ...
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Is using AES-256 with a key of less than 256 bits of entropy still quantum-resistant?

Encrypting with AES-256 is widely claimed to be post-quantum secure. But let's take a case where you use an initial key that has less than 256 bits of real entropy. In this example, let's work with a ...
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aeskeygenassist with only one imm8

I'm analyzing a binary which for its AES encryption, its only calling aeskeygenassist once and for the last argument (imm8, the ...
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Why RSA-KEM is more secure than Textbook-RSA?

I am studying RSA-KEM but I can not see why it should be as secure as padding RSA messages (e.g with RSA-OAEP) when exchanging a key between two parties (say A and B). It is easy to see that Textbook-...
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Key-Agreement & Key-Transport for Symmetric Authentication System

Question: I want to know what kind of Master Key sharing process is pursuit on Symmetric encryption environments (strictly symmetric, also in the key sharing scheme). As I am aware there are several ...
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Would XOR'ing two Argon2 keys add extra security?

When a user registers on the app, they need to provide a password they create and we provide them with a randomly generated passphrase (e.g. Apple Cat Ladder Fire). We then use Libsodium's ...
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memory-hard KDF that's just a giant permutation?

Why aren't there memory-hard KDF functions that simply build a 1GB permutation and permute it? Then hash the 1GB result. For example, use a hash function (unfixed output mode) on the key+salt and use ...
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Why use PBKDF2 over SHA-512 to derive AES encryption key? [duplicate]

Suppose I am using user passwords to derive AES-128-CBC encryption key. This key will be used to encrypt some sensitive data for the user so that even the website owner / operator can not decrypt it. ...
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Given a hash function; assuming domain % codomain = 0 and uniform collision distribution; how is entropy lost by collisions (not output truncation)?

Assuming our domain and codomain both have 4 elements, the uniform distribution of inputs to outputs means the function is injective. It is widely agreed that randomly selecting a domain element ...

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