Key generation is the process of generating keys for cryptography. A key is used to encrypt and decrypt whatever data is being encrypted/decrypted.

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How do certification authorities store their private root keys?

Knowledge of a CA private key would allow MitM attackers to transparently supplant any certificates signed by that private key. It would also allow cyber criminals to start forging their own trusted ...
86
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5answers
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SSH key-type, rsa, dsa, ecdsa, are there easy answers for which to choose when?

As someone who knows little about cryptography, I wonder about the choice I make when creating ssh-keys. ssh-keygen -t type, where type is either of dsa,rsa and ecdsa. Googling can give some ...
50
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4answers
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What is the best practice: separate ssh-key per host and user VS one ssh-key for all hosts?

Is it better to create a separate ssh-key for each host and user or just using the id_rsa key for all host to authenticate? Could one id_rsa be a malpractice for the privacy/anonymity policies? ...
26
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1answer
20k views

How should API keys be generated?

I want to make sure requests can't be forged and sent on to my server. In order to do this I need to generate an API key per user on my system. The purpose of the key will be to sign requests on the ...
19
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1answer
7k views

Where do I get prime numbers for Diffie-Hellman? Can I use them twice?

I realise it's very hard to generate suitable prime numbers and generators for the Diffie-Hellman key exchange. What is the best way to generate them? And if I have one, can I use it twice? ...
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4answers
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Generate cryptographically strong pseudorandom numbers in Javascript?

Is there any good way to generate cryptographically strong pseudorandom (or true random) numbers in Javascript? The crucial requirement: if a.com's Javascript generates some random numbers, no one ...
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4answers
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Is there any reason someone wouldn't use a longer key?

Larger key sizes are said to be more difficult to bruteforce; is there any reason someone would then decide to instead use a smaller key? Is there any negative effect in using a larger key size, such ...
15
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Creating user specific authentication methods in SSH

I have configured sshd on an Ubuntu server to use key authentication and it is working fine. I had to disable password authentication for key authentication to work. Server is always accessed via ...
15
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Why OpenSSL can't use /dev/random directly?

I couldn't find the answer for the reason anywhere, even the wiki page doesn't explain it. This seems like using a PRNG for seeding an another PRNG. The first one (/dev/random) may itself be seeded by ...
15
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2answers
625 views

Alternatives to HTML's deprecated <keygen> for client certs?

The keygen tag is used to make browsers generate private keys and POST the resulting CSR to the server, which can then issue a certificate. It's now been deprecated, for rather stupid reasons but ...
14
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4answers
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What are you doing when you move your mouse randomly during a truecrypt volume creation?

Is that called a 'round' every time you move your mouse when creating a new volume? I'm talking about the screen with the random numbers during the volume creation process. What is the purpose of ...
13
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2answers
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How many iterations of Rabin-Miller should be used to generate cryptographic safe primes?

I am generating a 2048-bit safe prime for a Diffie-Hellman-type key, p such that p and (p-1)/2 are both prime. How few iterations of Rabin-Miller can I use on both p and (p-1)/2 and still be ...
13
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3answers
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Can I use the same password both for SRP and for client-side encryption?

Suppose a less-than-trusted server is used to store users' confidential data (encrypted at the client side), and both tasks - authentication and encryption/decryption - should be doable with a single ...
12
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3answers
13k views

What is the DUKPT Key Derivation Function?

I'm tasked with decrypting ciphertext acquired from an encrypted card reader. The card reader utilizes DUKPT(derived unique key per transaction) scheme and 3DES encryption. I don't have a problem with ...
12
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1answer
1k views

MPPE-Send and Receive key derivation from MS-CHAPv2

I am trying to get the MS-MPPE-Send-key and MS-MPPE-Recv-key from the MS-CHAPv2 challenge material. I am able to follow the RFCs 2548 3078 and 3079 to the step of getting the GetNewKeyFromSHA() it is ...
11
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5answers
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Generate a PGP key with more than 4096 bits?

I would like to know if generating a PGP key with a number of bits higher than 4096 is possible and if so how?
11
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3answers
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Is TDEA (TripleDES) invulnerable to the weak keys of DES?

The key space of DES includes some keys that are weak, which results in a ciphertext that is extra vulnerable to cryptanalysis. Is TDEA (also known as TripleDES) invulnerable to those weak keys? Or, ...
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6answers
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Should I hash a password if it is randomly generated

The best practice is we should hash a user password using algorithms such as bcrpyt to protect the user, however, given the following conditions, is hashing in the backend still matters? the ...
9
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5answers
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What does key signing mean?

What exactly does the "key signing" mean? So for example I have a private/public GPG key so that people could send me encrypted e-mail, because they know my public key. But: what does key signing ...
9
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1answer
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HKDF and key stretching

I thought that all key derivation functions would do a key stretching phase, by iterating some kind of process. But I can't see that process in HKDF. HKDF doesn't do key strengthening? If I have a ...
9
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1answer
994 views

Would it make sense to use Bcrypt and PBKDF2 together?

I've read various opinions about whether Bcrypt or PDBKF2 is a better key derivation hashing method. The answer seems to depend on a lot of complicated factors that are not easy to analyze. Would ...
9
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1answer
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Using HMAC to generate secret keys

I am developing a platform that uses several secret keys for several usages: key1 for hashing passwords (using pbkdf2-hmac-sha256), key2 to generate non-repeating unpredictable uuids (using aes-128 ...
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3answers
382 views

How can I allow acces to encrypted data if only 2 out of 3 users provide a secret?

I want to encrypt data, but make sure that no single user can decrypt the data. Further, it is important not to require ALL users to be present to decrypt. This will allow for some flexibility and ...
8
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1answer
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Is a 2047-bit prime weaker than a 2048-bit prime?

I have a safe prime generator I'd like to speed up. I can benefit from a significant performance gain if the high order bit in the returned prime can be either 1 or 0. The returned prime would be ...
8
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2answers
562 views

Can the human brain generate cryptographically secure random numbers?

A security conscious friend of mine was attempting to generate entropy using random dice rolls to generate a random password, and I became curious about the security of random number generators and ...
7
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Is it possible to make a more secure random number generator algorithm by XORing two or more less secure random number algorithms?

Is it possible to make a more secure random number generator (e.g. for cryptologic purposes) by combining two or more less secure random number generator algorithms using XOR? Here is an example of ...
7
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3answers
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Where does StartSSL generate the cerificate, server or client-side?

I.e. do really only I have the private key or do I have to trust that StartSSL (or any other provider) don't store it themselves?
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2answers
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What is the difference between DHE and ECDH?

I learned that perfect forward secrecy is implemented through DHE and ECDH but what is the difference between these 2 key exchanges? Also can someone explain how perfect forward secrecy works? I've ...
7
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1answer
143 views

Is a 43 character GPG (symmetric) passphrase as secure as a 256-bit key?

A 43 character securely randomly generated mixed case alphanumeric password (with 2 extra chars to give 64 possibilities per character) would constitute 258 bits of entropy (6 * 43 = 258). Since the ...
7
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1answer
412 views

RSA key generation: gpg vs openssh

When I generate RSA key for ssh (both server-side and client-side): dpkg-reconfigure openssh-server ssh-keygen the key generation is completed instantly. However, when I generate RSA key for gpg, ...
6
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2answers
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What happens if two parties have a same pair of public&private keys

we know that we have to create Private key on server and generate its public key and create a certificate. But what if we get a private key which someone already has. Isn't the security becomes weak ...
6
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How much added security do I really get with a longer key size?

Imagine I have a cipher which supports keys of 128, 192 or 256 bits. Suppose that there are no vulnerabilities in the cipher regardless of key length. I'm going to use it to encrypt something, and ...
6
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1answer
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Select a TripleDES key so that it effectively behaves as regular DES

I'm working with a smartcard (DESFire) that supports both TripleDES and DES. In the specs it is stated that both modes of operation use 16 bytes keys. When the first 8 bytes in the key are identical ...
6
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2answers
792 views

How can you securely generate keys on AWS?

Our application needs to generate secure keys for long term storage on AWS using openssl. But I've seen some instance where entropy falls dangerously low on AWS machines and this doesn't appear to be ...
6
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1answer
194 views

Creating a Private Key using Human Intervention

In a hypothetical system, lets say that a design requirement is that people who snoop around the database of a web application (sysadmin gone rogue, or what have you), do not have access to the plain ...
6
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4answers
809 views

Relationship of password strength and key strength

I have just started educating myself about cryptography, and while it is mostly making sense, a few things are still eluding me. One being: In systems that take a user's pass-word/-phrase in order to ...
5
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3answers
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Can the salt for PBKDF2 be a hash of the user-entered password?

I want to derive a key from a password in a client application that will be used as a master key that decrypts a data key. As far as I understand the salt should be private knowledge. Would it be ...
5
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4answers
968 views

Is it possible to detect SSL private key changes?

I wonder if it would be possible to detect a change of an SSL private key? If you change the key, then I think one must issue a new certificate, but new certificates could be issued without changing ...
5
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2answers
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TrueCrypt and Keyfiles hidden among 500,000 other .pdf files

A question from a newby: I have a USB or Standalone HardDrive with a TRUECRYPT hidden partition on it that needs one or more "keyfiles" and a password to access. What tells the attacker what kind ...
5
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2answers
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Understanding PRGs: How can we expand randomness?

I am getting a bit confused with the PRGs employed in cryptography. Basically, a PRG is used to expand a random sequence (mostly a key) of length s to a length n>s, still looking random. Now while ...
5
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2answers
816 views

Best practice for password-protecting a secret key

What approaches are generally accepted for generating a password-protected symmetric key? My intuition is to generate and store a random string of appropriate length as the password-protected key, ...
5
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2answers
173 views

Best practices: Use of a single private key as a person, or multiple to identify self across domains?

Similar to the question here, I'd like to apply the same question to a person. For example, I have implanted a chip in my hand that holds an encrypted private key that serves as my personal unique ...
5
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1answer
76 views

Why is the Key Derivation Function important?

Let's consider this openssl command : openssl enc -aes-256-cbc -pass pass:PASSWORD Why is it important to have a good Key Derivation Function? This answer to another question suggest that GnuPG is ...
5
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1answer
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Security issues related to public keys and SSH

Do I have to mind something specific when using public keys and SSH? Well of course, I have to keep my private key secret (and therefore I should choose a strong pass phrase). But is there something ...
5
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1answer
103 views

Is this a safe way to verify public keys?

I want to verify a public key like this: Alice generates a public/private key pair for encryption Alice generates a public/private key pair for signing Alice signs a random 4-letter word + the ...
5
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5answers
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Should you notify software vendors that their software has been cracked?

Apologies if this is not the right place to ask this question, I will happily move it to another Stack Exchange site if need be. Before I explain the rationale behind the question, let me clear up a ...
5
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1answer
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Transparent key management for client computers

I'm tasked with adding a backup feature to our software. This backup feature should store the customer's database on external memory. One of the requirements for this feature is that the backup should ...
5
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Using plain-text phrases as public/private pair?

I'm working on an application that'll be used by relatively non tech-savvy users, and while the machines will have internet access, the app can't have any sort of hosted intermediary. The app allows ...
5
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2answers
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PKI/Why does Microsoft require my cert before encrypting an email?

Microsoft doesn't allow sending public-key encrypted messages using Outlook 2003-2012 on Windows 7-8x environments without first creating your own Digital ID or private key for signing. Per ...
5
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1answer
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Asynchonous Linear Feedback Shift Register : test vectors

Well I've been working on coding LFSR structures for my research projects. Being able to find sources on the subject, I've been able to test a single LFSR with different initialisation and TAP ...