Tagged Questions

6
votes
2answers
76 views

Backup schedule for Encryption Keys

How often should encryption keys be backed up? Should this be done on the same schedule as the encrypted content/configuration? That seems excessive, as the keys do not change as often. Perhaps ...
1
vote
1answer
138 views

Exchange of DEK and KEK (encryption keys) between app server and key server

In my application, it is required to encrypt a user's data before inserting it into the mysql database. I am using AES algorithm to encrypt the data using a 256 bit hash (and is calling it Data ...
1
vote
4answers
304 views

SSH: reusing public keys and known-man-in-the-middle

Usually, people recommend to use a single private-public key pair everywhere (if we're not talking about a possibility of compromising the private key): Best Practice: “One per-user ssh key” or ...
7
votes
3answers
294 views

AES using derived keys / IVs. Does it introduce a weakness?

I'm looking for an efficient way to encrypt multiple fields in a database with AES using a single global key, used throughout a large web application. Obviously in order to re-use this key, a unique ...
3
votes
4answers
672 views

Asymmetric crypto: Decrypt own messages without having private key

I have built a messages system for my website. Users can send the admin messages which are stored in the DB after being AES-encrypted. I think that using asymmetric crypto (RSA through openssl) ...
5
votes
3answers
3k 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 ...
25
votes
4answers
5k views

How can PrivateSky not see your data?

PrivateSky is a website that promises encrypted "cloud-like" secure information exchange. They promise that except the sender and receiver, nobody can see your data. After testing it yesterday, I do ...
3
votes
1answer
489 views

Storage of 'secrets', keystores, HSMs and the rest

I've been digging for the past few days into storage of sentitive data. If I store this data in a database, I believe the general accepted practice is to store sensitive data encrypted, for various ...
6
votes
5answers
3k views

What does “key with length of x bits” mean?

I'd like to know what it means to say "the cryptosystem C uses keys with a length of x bits". I do not understand what the bits length means... doesn't it depend on the encoding? The same word encodes ...
2
votes
3answers
1k views

RSA 4096 with AES 256 Encryption Process Using PyCrypto

I have the following process for encrypting and decrypting data in a python script using the PyCrypto module: Encryption - Server A AES 256 shared key is generated Associated IV is generated Data ...
1
vote
2answers
468 views

Need example and working Security Token Service (STS)?

Can anyone explain or post any link to a simple example and introduction about the Security Token Service (STS)?
7
votes
3answers
407 views

Server to server encryption: Key rotation over the air. Can it improve security?

In my other question, I explored whether to write my own encryption or use an existing one. I was advised to use TLS or AES or something that is established. This question is about key rotation. It ...
2
votes
1answer
994 views

DUKPT - Sample data other then in X9.24

I wrote some code that does PIN encryption/decryption according to rules in X9.24. It works great with examples provided in ANSI doc, but doesn't work with actual device from the client. Where can I ...
2
votes
4answers
649 views

Are there any “real world” implementations of secret-sharing encryption schemes?

Imagine something like TrueCrypt where user A can decrypt his files, or any 3 of the 10 directors in his organization can decrypt user A's files. As I understand it this is similar to the way the ...
6
votes
1answer
524 views

Public key length

I was wondering if there was (and I hope there is) a standard for public key size for ECDH (Elliptic Curve Diffie-Hellman) and ECDSA (Elliptic Curve Digital Signature Algorithm) for every curve type ...
73
votes
3answers
44k views

RSA vs. DSA for SSH authentication keys

When generating SSH authentication keys on a Unix/Linux system with ssh-keygen, you're given the choice of creating a RSA or DSA key pair (using -t type). What is the difference between RSA and DSA ...
3
votes
2answers
503 views

When should I use Message layer encryption vs transport layer encryption

Basically I will be having to secure a connection between different hops. Therefore even if TLS is widely known to be the best in class, I am wondering that in such a case message based encryption ...
9
votes
5answers
1k views

Use RSA keypair for PGP encryption and decryption

Is there a way that I can use a RSA keypair with PGP? What I mean is that I have 2048 length keypair and i want to use that to encrypt and decrypt data. But all I have found is that the PGP uses some ...
4
votes
2answers
2k views

mysql AES_ENCRYPT key length

AES_ENCRYPT uses a 128 bit long key to encrypt the data, but how does mysql handle longer or shorter keys? I found out that pycrypto for instances recomend to transform the key by using md5 sha1 sha2, ...
3
votes
1answer
149 views

Help on interpretation of FIPS-140 paragraph

This is from the FIPS 140-2 standard: Cryptographic keys stored within a cryptographic module shall be stored either in plaintext form or encrypted form. Plaintext secret and private ...
8
votes
3answers
742 views

Security implications of storing the password hash along an encrypted AES key

I am using the PKCS#5 standard to generate a key using a random and unique salt and the user's password in input. Consider this key as the "encryption" key. The "encryption" key is used to encrypt a ...
10
votes
6answers
766 views

Shouldn't GPG key fetching use a secure connection?

If I run this for example: gpg --keyserver hkp://keyserver.ubuntu.com --recv-keys 0xFBB75451 then does the importing occur in a secure way? I mean does it go over only secured connections? (HKP?) ...
23
votes
6answers
1k views

Is using a public-key for logging in to SSH any better than saving a password?

Using a public/private key pair is fairly convenient for logging in to frequented hosts, but if I'm using a key pair with no password, is that any safer (or less safe) than a password? The security ...
8
votes
3answers
25k views

How can I export my private key from a Java Keytool keystore?

I would like to export my private key from a Java Keytool keystore, so I can use it with openssl. How can I do that?
7
votes
3answers
1k views

Additional security of keyfile on top of a master password for KeePass

I use KeePass + Dropbox to manage and synchronize my passwords across my devices. This system works really great and I trust KeePass' security model. However my biggest remaining concern is the ...
3
votes
2answers
157 views

Encrypting a fixed format message?

I'm planning to send across TWO pieces of information over the internet from machine A A site identifier which will be like: $SiteName = "EXAMPLE" (in plaintext) Encoded text which will be like: ...
4
votes
2answers
141 views

Question about the SessionLock paper

Some time ago there was a big fuzz over Firesheep: by listening to wifi traffic your login session can be stolen which is very bad because now somebody can e.g. send emails on your behalf. Some people ...
5
votes
5answers
892 views

Should one sign and encrypt using the same key? The Azure Training Labs are taking this approach

I'm taking the Azure lab LoadBalancing with WCF and recognise what I have been told is bad from a security perspective, but am not sure if it applies here. Can someone look at this code and tell me ...
7
votes
2answers
1k views

Data Encryption and Key Management in C#

Which route to take, what are the pros and cons, which is more secure.. Generate AES key, encrypt the data with it and then encrypt the AES key with RSA, save the encrypted data and encrypted AES ...
12
votes
4answers
784 views

Is Steganography considered encryption and subject to USA export restrictions?

I have written an application for Apple's iOS which embeds messages in JPEG files using steganography (see http://en.wikipedia.org/wiki/Steganography). For the purposes of this question lets assume ...
5
votes
2answers
589 views

Generating one-time tokens from API-key?

I have a web-site for which I'm building a Drupal module that allows the users of that Drupal site to navigate to my web-site directly from the Drupal site. I intend to distribute secret API-keys to ...
13
votes
3answers
1k views

What are the chances to generate the same ssh key?

I could generate ssh keys on the client like (without password): ssh-keygen -b 8192 -t rsa -f /home/THEUSER/.ssh/id_rsa -P '' -v and copy the generated id_rsa.pub to the server: ssh-copy-id -i ...
4
votes
3answers
297 views

Are there any serious problems with this technique for generating symmetric keys?

I'm using a technique borrowed out of a book by Bruce Schneier and Niels Ferguson called Practical Cryptography. Basically, it boils down to this: Bob does this: pubk_A = Alice's public key ...
3
votes
4answers
321 views

Generating OpenPGP key pair with restrictions

I intend to generate an OpenPGP RSA key pair where a part (~half) of the private key is as I specify, i.e. a specific string. Are there tools for generating a key pair with such restrictions, or will ...
10
votes
3answers
574 views

Key management in cloud datacenters

In terms of infrastructure, how do Cloud providers (organizations providing SaaS, PaaS, or IaaS via the cloud) manage keys and cryptography? From my understanding, "private" datacenters tend to ...
8
votes
5answers
7k views

Compute the AES-encryption key given the plaintext and its ciphertext?

I'm tasked with creating database tables in Oracle which contain encrypted strings (i.e., the columns are RAW). The strings are encrypted by the application (using AES, 128-bit key) and stored in ...
8
votes
5answers
338 views

What can one do when encryption methods fail?

I'm in search of an expert to answer my curiosity. Suppose that methods like AES/DES, SSH, PGP, RSA, etc. can be cracked or fail somehow. In other words, suppose that it's possible to determine one ...
6
votes
1answer
1k views

Is SSL key generation client-side, server-side, or both?

Who generates the session keys for a SSL symmetric encryption? Is it the client for both client and server where client generates part of it while the server generates the other part?
6
votes
1answer
2k views

How can I enumerate all the saved RSA keys in the Microsoft CSP?

I have an application that is creating several keys and storing them in various stores (in this case the Machine store). How can I enumerate all the keys on a given Windows system? ...
3
votes
1answer
2k views

How do I use C# to encrypt/decrypt data where the private key is on a smartcard, hardware security module, TPM chip etc

Is anyone aware of a C# code sample to interact with smartcard, hardware security module, TPM chips (etc), that will allow me to encrypt and decrypt data? My goal is to allow my application to ...
8
votes
3answers
1k views

What common products use Public-key cryptography?

I want know what common use products are there that use public key/private key cryptography?
20
votes
5answers
2k views

PCI Encryption Key Management

(Full disclosure: I'm already an active participant here and at StackOverflow, but for reasons that should hopefully be obvious, I'm choosing to ask this particular question anonymously). I currently ...
6
votes
3answers
520 views

What are the pros and cons of outsourcing an organization's PKI?

I am looking for the pros and cons of outsourcing an organization's Public Key Infrastructure (PKI). I understand that the answer to whether or not to actually outsource is going to depend on the ...
10
votes
2answers
982 views

GnuPG/OpenPGP Key Practices

I'm looking for input on GnuPG (gpg) best practices. It's been discussed some on the gnupg-users mailing list, but I wanted to get as diverse a view as possible, so I thought to bring the topic to ...
13
votes
2answers
1k views

How secure is Keychain on OS X?

Keychain is a built-in app on OS X that stores all of the user credentials, and allows for one to keep encrypted notes in an easily accessible way. Does anyone know how secure Keychain is? I know ...
28
votes
6answers
9k views

How should I distribute my public key?

I've just started to use GPG and created a public key. It is kind of pointless if no-one knows about it. How should I distribute it? Should I post it on my profile on Facebook and LinkedIn? How about ...