Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for ...

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46
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5answers
11k views

Why should one not use the same asymmetric key for encryption as they do for signing?

In an answer to a question about RSA and PGP, PulpSpy noted this: It is possible to generate an RSA key pair using GPG (for both encryption and signing -- you should not use the same key for ...
3
votes
0answers
272 views

What are the vulnerabilities of this homemade encryption algorithm? [migrated]

I decided to program a relatively trivial encryption algorithm in my downtime. This algorithm takes a seed from a user (supports floating point seeds), and then adds 1 to the seed for every iteration ...
4
votes
6answers
378 views
+100

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 ...
-1
votes
1answer
51 views

What encryption algorithm does CryptEncrypt in Crypto API use?

I am writing a code to perform encryption and decryption using CryptEncrypt and CryptDecrypt functions, a part of Windows' Crypto API. Can anyone tell me what kind of encryption these two function ...
26
votes
3answers
6k views

symmetric encryption session keys in SSL/TLS

This question concerns the session send and receive keys used in SSL/TLS protocol. my understanding is that this key uses symmetric encryption (DES, AES, BlowFish, etc.) I'm wondering, if ...
0
votes
2answers
323 views

Generating authentication token from PHP sessions

I have a traditional PHP site which uses sessions. I've developed a real-time app in nodejs and wish to authenticate users here based on their PHP session. The procedure would go something like this: ...
-2
votes
0answers
33 views

Encoding scheme and padding with '=' [on hold]

Does anyone know which algorithm uses '=' as padding character besides Base64? I got the encoded text ...
2
votes
1answer
43 views

difference between public key and host key and security of host key

In SSH, what is the difference between host key and public key. Public key I believe that is part of private/public key pair, so, that anything sent by server(encrypted using private) can be ...
1
vote
2answers
139 views

Using OAuth 2.0 without token storage

I am building a system for a product which requires Authentication and Authorization. Naturally I have chosen using OAuth 2.0 as it is a commonly used protocol and has proven to be useful. I am ...
0
votes
0answers
19 views

How should I approach learning Verifiable Encryption?

I need to act as a proxy for certain types of encrypted data, and I want to make sure that my service isn't abused. To that end I need to verify the general structure of the data going through my ...
2
votes
1answer
63 views

Why does WPA2 need a 4 way handshake?

If client and AP both have the Pairwise Master Key (PMK) available, why do we need a 4 way handshake again to derive some other key (PTK)? Why can't we use PMK for further security process?
1
vote
2answers
133 views

How to store derby database encryption key in HSM?

The Derby Database supports encryption with a key or password. Traditionally this key is stored in the file systems, now I am looking to store and protect this key in the HSM instead, but I couldn't ...
0
votes
1answer
32 views

Subject verification of certificates

Suppose H has taken C’s certificate and manually changed the subject information in C’s certificate from C to H. Would this modification be detected by A during the certificate verification process?
0
votes
1answer
111 views

Crypto Ransomware - How decryption is done when user accept to cooperate?

When you have been "hacked" and you accept to pay for decrypting your encrypted files, how the attacker do the job ? I understood that a symmetric key is used, itself encrypted by the attacker public ...
7
votes
4answers
430 views

Decentralised password recovery

Are there good/established techniques for password/key recovery in situations without a centralised service? (Anything goes, but I'd prefer solutions that distribute the recovery information across ...
140
votes
3answers
115k views

What's the difference between SSL, TLS, and HTTPS?

I get confused with the terms in this area. What is SSL, TLS, and HTTPS? What are the differences between them?
2
votes
2answers
114 views

Reducing hash output length [duplicate]

I am using output of (keyed) hash function to make sure the input was not modified, I store it along with input. Now output of SHA-1 is 20 bytes. Say I want to reduce the output. And have it output 10 ...
1
vote
1answer
28 views

Is CAST5-CBC as supported by OpenSSL an authenticated encryption method?

I'm looking to encrypt some files using a simple cipher plugin. I have access to using AES-256 in CBC mode, but this doesn't offer message authentication and I'd have to build my own HMAC for it. ...
0
votes
0answers
47 views

Is it dangerous to use the same key (RSA) for both encryption (PGP) and authentication (SSH)?

Alice wants to send an encrypted message to Bob, but she also wants to connect to Carol's server. Are there any dangers associated with using the same RSA key for both PGP and SSH (other than a lack ...
28
votes
4answers
19k views

How does PGP differ from S/MIME?

Is S/MIME an abstracted system for general MIME type encryption, whereas PGP is more for email? Why would I want to choose one over the other, or can I use both at the same time?
0
votes
2answers
112 views

Untraceable Digital Cash?

I have read some articles regarding digital cash with untraceable(Here). Their protocol is provided below Withdrawal: Alice creates an electronic coin and blinds it. Alice sends the blinded ...
0
votes
0answers
11 views

Finding out key size used in ECDH algorithm in C#? [migrated]

I am a beginner when it comes to any EC algorithm, so please help me understand this basic question. While reviewing the C# code, how can we find out the key-size used in the ECDH implementation? or ...
1
vote
1answer
20 views

How can i store encryption key into Microsoft provided Key container?

I'm working on an application in which user will enter encryption key via GUI and my app will fetch that encryption key. Now i need to store that received key into Microsoft key container. I got this ...
0
votes
1answer
170 views

Asymmetric vs Symmetric Encryption Benchmarks

I have found these benchmarks in Crypto++'s site. http://www.cryptopp.com/benchmarks.html But I am, quite honestly, not entirely sure how to interpret them. I am really looking for a set of ...
2
votes
2answers
120 views

Encrypting USB traffic: Is RSA necessary for AES session key exchange when using pre-installed secret keys?

I need a solution to encrypt USB communication between device A and device B. I was thinking about configuring each device with a secret RSA-2048 key, which would be used to exchange an AES-256 ...
7
votes
3answers
3k views

Google Chrome “Your connection to website is encrypted with obsolete cryptography”

Google Chrome is showing new information in the certificate section. Is this a big deal? If so how can I fix it on the server end? EDIT: Thanks for the answers but I'm not skilled in cryptography ...
4
votes
3answers
13k views

CryptoWall 3 - how to prevent and how to decrypt?

My father's computer is now infected with CryptoWall 3, according to the link below. http://www.bleepingcomputer.com/virus-removal/cryptowall-ransomware-information#CryptoWall Is there a way to ...
0
votes
0answers
22 views

Which stream ciphers are supported in am335x cryptographic accelerator?

I want to use cryptographic accelerator in aes cfb mode [or any other stream cipher]. According to http://e2e.ti.com/support/arm/sitara_arm/f/791/p/156983/658334 link cfb is supported in am335x. I ...
1
vote
1answer
97 views

How does OTR's authentication using “Question and answer” protect against MiTM?

I've read that the answer has something to do Socialist Millionaire, but I still don't understand how can the user be protected against malicious Man In The Middle, which would capture the question ...
2
votes
1answer
301 views

Requiring 2 keys to access a content

I need to use an external service that can only be accessed by password. I don't like the idea of storing the plaintext password on the server, but AFAIK there's not much I can do. Considering this ...
2
votes
0answers
25 views

Statistical saturation attack on block ciphers [migrated]

I was wondering if anyone around here could give me some explanation on this type of attacks. Pretty much the only thing that I could find is this What I really need is basic explanation of the ...
50
votes
4answers
5k views

What kinds of encryption are _not_ breakable via Quantum Computers?

There's the recent article NSA seeks to build quantum computer that could crack most types of encryption. Now I'm not surprised by the NSA trying anything1, but what slightly baffles me is the word ...
24
votes
6answers
10k views

Could SQRL really be as secure as they say?

I just came across https://www.grc.com/sqrl/sqrl.htm With Secure QR Login, your phone snaps the QR code displayed on a website's login page . . . . and YOU are securely logged in. This ...
16
votes
4answers
3k views

Is it dangerous to publicly share ciphertext?

Alice wants to share a message with Bob, but Alice and Bob can never be in the same place at the same time. We can assume they both know each others public keys (or agreed on a shared key, if that ...
2
votes
1answer
147 views

Does OpenSSH use export ciphers?

With all of this talk of 'FREAK', no one has mentioned OpenSSH. It implements libraries from OpenSSL (until recently, anyway). Why aren't people talking about this? is there even a way to configure ...
0
votes
1answer
95 views

Client authentication with a collection of open source distributed servers

With a collection of open source distributed servers, all sharing every users data. How can the user authenticate with any server, without the passwords being compromised by a malicious server? ...
2
votes
3answers
103 views

Simple string comparisons not secure against timing attacks [duplicate]

As I learned in a comment for How to encrypt in PHP, properly?, I was told using a string comparison like the following in PHP is susceptible to timing attacks. So it should not be used to compare two ...
17
votes
1answer
453 views

How to encrypt in PHP, properly?

How do I encrypt data in PHP, properly, using symmetric-key encryption? I have a message M and a secret S. I'm looking for a solution that uses cryptography properly without making any of the usual ...
15
votes
1answer
11k 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 ...
233
votes
7answers
177k 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 ...
85
votes
6answers
29k views

Password Hashing add salt + pepper or is salt enough?

Please Note: I'm aware that the proper method for secure password storage hashing is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. ...
0
votes
1answer
86 views

How can I tell if my client has been infected with CryptoWall?

Today a client ran a file they believed to be something else, they said a black window appeared, so I checked the code to see what it ran in CMD, but can't quite work out what it's doing. I've just ...
7
votes
4answers
299 views

How to check randomness of random number generators?

Assume that I have a smart card that returns an 8 byte (for example) random value on reception of a command. The question is that: How I can check if this value is really random? (I don't have any ...
0
votes
1answer
57 views

Can you recover the password from ZipCrypto encrypted ZIP file?

I know that "legacy ZIP-crypto" is not secure and you can get at the contents of the file quite easily. Now the question is, can you also get at the password (assume this is a very long, very high ...
1
vote
1answer
80 views

How to keep a reasonable level of entropy in an encrypted file?

Encrypted (or random) data, by nature exhibit a high entropy value and non unencrypted data will exhibit a low entropy value. From an attacker point of view the precense of this high entropy value in ...
0
votes
0answers
15 views

Can AES IGE be parallelized? [migrated]

As far as I know in AES IGE each block depends on the previous one. In that case can it be parallelized. Is there some way to do it??
0
votes
1answer
30 views

length of a session key in EC?

In elliptic curve cryptography what should be the length of session key? Is there a specific metric to choose one, or are they randomly generated? I was studying one paper about defence against a ...
0
votes
1answer
117 views

Publicly Available API + Sensitive ID/Key Transmission Over HTTP

I've run into a predicament... I'm developing a mobile application that utilizes a server for various things. One portion is that it stores an id/key pair related to accessing and processing ...
3
votes
1answer
98 views

Security of hybrid encryption scheme

I want to use a hybrid encryption scheme for file encryption. The scheme must use PKCS#1 v1.5 – which is vulerable to padding oracle attacks – because many smartcards (e.g. the OpenPGP Card) only ...
1
vote
1answer
39 views

ssl+symmetric with my own encryption algorithm? [closed]

I am a final year student currently doing my project, the title is "Mitigating man in the middle attacks using ssl+symmetric key algorithm". I would like to create my own encryption algorithm. I need ...