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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How secure is Certivox M-PIN?

CertiVox have designed a system with the aim of "getting rid of passwords". Essentially the system authenticates users with two factors of authentication: A 4 digit PIN and a token stored within the ...
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1answer
29 views

Google Chrome obsolete cryptography

I have a apache server running and following configuration for ssl: Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains" SSLProtocol -all +TLSv1.2 SSLCompression Off ...
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1answer
43 views

Linux Kernel module signing

If the linux kernel is compiled to check for kernel modules signing, it checks the validity of the public key (X.509) w.r.t the current system time. For the first time the system is booting up, it ...
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1answer
83 views

What can I do if someone is using my IP address? [on hold]

Another device in my network is using my IP address, what can he do if he is using my IP address? Is this a crime? Can him be caught by police or sue by Malaysia government?
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2answers
95 views

RSA public key and private key lengths

I'm having a problem understanding the size of an RSA public key and its private key pair. I saw different key sizes for RSA algorithm (512, 1024,... for example), but is this the length of public ...
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1answer
49 views

SSH Key: Ed25519 vs RSA

A lot of people recommend using Ed25519 instead of RSA keys for SSH. The introduction page of Ed25519 (http://ed25519.cr.yp.to/) says: [..] breaking it has similar difficulty to breaking [..] RSA ...
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0answers
30 views

Cryptographic enforcement schemes using Diffie-Hellman [migrated]

If one wants to set up a decentralized cryptographic enforcement scheme in which the level of 'confidentiality' of information is marked by its position in a poset, why not use Diffie-Hellman to ...
2
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2answers
102 views

Are hashes of hashes used for password storage in practice? Why/why not? [duplicate]

A naive developers might store a password in the database directly, which would then be compared directly with the password sent from a client. A more security conscious developer might instead store ...
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1answer
67 views

Is HTML5 sessionStorage secure for temporarily storing a cryptographic key?

Assume I am building a local web application (e.g. browser extension) in HTML5 to encrypt a database locally. Access to the database is controlled by a password and a cryptographic master key is ...
2
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1answer
28 views

How can the parallelization in CTR mode be attained?

I am using CTR mode to encrypt/decrypt files. Theoretically CTR mode is faster than CFB or CBC because of its individual operations on blocks. In my case CTR mode takes almost as long as CFB. How can ...
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2answers
51 views

Can I use AES CTR mode to encrypt files with same key and nonce?

I want to encrypt the files stored in SD card and I am using the CTR mode of AES to encrypt it. The key and IV are fixed. So each time I encrypt/decrypt I use the same key and nonce. Most of the ...
5
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3answers
130 views

Does TLS_FALLBACK_SCSV provide blanket protection against downgrade attacks?

The TLS_FALLBACK_SCSV flag was touted as a way to prevent POODLE, which abused the potential to downgrade to SSLv3 from TLS. Does the implementation of this flag prevent similar downgrade attacks ...
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20 views

Topics to start an interest group at our company [closed]

Good afternoon everyone, I'm looking to start a Communities of Practice at my job. Our company is largely involved in application development for our customers but we also want to get into, what my ...
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1answer
54 views

Crypto for penetration test [closed]

I'm a newbie but I want to become a penetration tester. I'm taking a course on cryptography but I'm wondering... how useful is crypto for penetration testing compared to other skills like operating ...
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0answers
41 views

What is the difference between XOR and poly-XOR? [closed]

What is the difference between XOR and poly-XOR in encryption?
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1answer
56 views

Cryptowall encryption files

This is a question concerning the way the Cryptowall ransomware encrypts files on the victim's computer. Someone knows if it is possible to recover the encryption key comparing the encrypted file and ...
1
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1answer
51 views

Prevent padding oracle attack on key exchange process

I found in my searches that the padding oracle attack can be used against the RSA with PKCS1PAdding or OAEP padding, and I used this algorithm for a symmetric key exchange. How can I prevent a padding ...
3
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2answers
74 views

Can the intended recipient be derived from a public-key encrypted ciphertext?

Assuming you have a list of possible recipients' public keys, and a ciphertext encrypted with one of those public keys, would it be possible to determine which public key?
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1answer
50 views

RSA: same symbols in plaintext give same symbols ciphertext?

I just started studying Information Security, but I just ran this program: http://www.sanfoundry.com/cpp-program-implement-rsa-algorithm/ and faced this strange thing. For small keys (don't try to ...
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0answers
40 views

Designing a security system for road pricing

It's my first semester with Information Security and I still feel a little lost. Sorry in advance for stupid mistakes I may have made. the examples in round brackets below are my own ideas, wrote ...
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3answers
36 views

What type of hashing method is used for the private key to encrypt for signing messages?

To use RSA for signing, Alice takes a hash of the message, encrypts the hash using her own private key, and appends the result (this is the signature) to the message. Eve can of course still ...
4
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3answers
44 views

GnuPG symmetric encryption yields different output

I have a use case where I want to commit symmetrically encrypted source code using GnuPG (think of Coursera assignments for backup and collaboration). I encrypt/decrypt all sources in a batch with a ...
0
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1answer
89 views

Analyzing a TLS connection?

Suppose I want a secure TLS communication between me and myschool.edu. Which of the following should I trust to preserve confidentiality, integrity, and authenticity. Here are the options and my ...
0
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1answer
107 views

Prevent CryptoLocker on Server

A quick question, which may have a not-so-quick answer - Are there any ways to prevent files associated with CryptoLocker, to be propagated to a data server, by means of a back up? We use Cobian as ...
4
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0answers
31 views

At what point can you you implement crypto algorithms? [migrated]

First off, this feels like it should be a common question, so I'm sorry if I've missed an older thread. Note that in my question, I'm talking about "implementing AES" rather than "designing AES2" or ...
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2answers
256 views

What are the differences between TPM and HSM?

TPM (Trusted Platform Module) and HSM (Hardware Security Module) are considered as cryptoprocessor, but what are the differences exactly? Does one of them have more advantages than another?
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InvalidKeyException using ECPublicKey [migrated]

I'm getting the following exception when i try to encrypt a byte array with a EC public key : java.security.InvalidKeyException: No installed provider supports this key: ...
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2answers
89 views

Crypt-analysis methods for breaking or finding weakness in an encryption algorithm? [closed]

How cryptanalysts work on an algorithm related to diffusion/confusion factors in order to find a weaknesses in an algorithm, for example how cryptanalysts could find weakness on DES? is there methods ...
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4answers
81 views

How does PKI work for the client side?

As I send this question as a request to yahoo's server, the information in the request will be encrypted with yahoo's public key (which is available for everyone). Then the information will arrive at ...
2
votes
5answers
155 views

Does publishing the md5sum of a private key compromise the private key in any meaningful way?

If I have a 4096 DSA private key used for signing binaries, and I want to ensure that a partner has an identical server using the same private key, can I send the md5sum of the private keys over an ...
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1answer
23 views

How to get my GNUPG Elgamal private key exponent?

I have tried googling around. The closest solution I get is: private.key contains the private key file. $pgpdump -i private.key But this only gives me the following: ElGamal p ElGamal g ElGamal y ...
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votes
2answers
91 views

Is it a secure encoder and hasher?

I want to ask if my code secure or not. if this is not secure please tell me the reason. This code is mixed of Rjindael-256, base64_encode and SHA-512. function xencoder($input,$key) { $salt = ...
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votes
0answers
62 views

Can I use the output from a DRBG directly as K for AES, or do I need to use a key generator algorithm? [migrated]

NIST has 3 validated "Recommendation for Random Number Generation Using Deterministic Random Bit Generators" (DRBG's) that are based on NIST SP 800-90A: Hash_DRBG (based on hash functions) ...
4
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2answers
146 views

How does a Tor exit node know the public key of the client?

When the Tor exit node executes the client's request and receives a response from the server, it must create an onion cell that can be reversely decrypted along a circuit through the Tor network. ...
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1answer
87 views

Does it increase the security if we split data to n pieces and encrypt each one with different key and different algorithm?

For example: a 10 MB file will be sliced to 10 pieces (each 1 MB) and then dispersed between network nodes. Each node will encrypt it with its own key and different algorithm (AES, TwoFish, Blowfish, ...
2
votes
2answers
125 views

How can an attacker identify the encryption method with only ciphertext?

Assume that attacker only could obtain ciphertext, but knows that method is symmetric. Is there a way to find which algorithm was used for the encrytion? And in general, if attacker knows the ...
6
votes
1answer
511 views

can multiple encryption of data with multiple keys increase the security?

I mean: does encrypting data multiple times have an effect on diffusion and confusion? Does it increase security, or does it have no effect? Is it useless? Does it make it harder to break the secret, ...
1
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1answer
43 views

SSH: What's the difference or interplay between /etc/ssh/[host files] and ~/.ssh/[public key]

I'm new to SSH after a decade of dabbling with Ubuntu and other Linux builds. Today I successfully setup SSH, but I had a few hangups and headaches along the way. Although the system is now running ...
5
votes
1answer
106 views

Showing bank routing/account numbers, and storing them safely

EDIT: This is for the UK/Europe region. I've been scratching my head reading other posts similar to this one about safely storing bank routing and account numbers. I know that routing numbers can be ...
18
votes
5answers
936 views

How can I explain “zero knowledge proof” to an end user?

A ZKP allows proof of knowing the answer to a secret, without actually disclosing what that answer is. Is there any analogy that can help people put this concept into everyday practice? A "lie to ...
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3answers
94 views

Sharing a common public and private SSH keys for a cluster of machines

I guess this is way to settle an internal debate I am having with myself. In my provisioning process, I am wanting to share a common public and private ssh keys for each machine in a clusters, ...
3
votes
1answer
127 views

Is this symetric or asymetric encryption?

I’m at the beginning of my journey into the world of security. I am reading about the most fundamentals topics and I have encountered something unusual that has thrown me. The Conundrum: I have come ...
1
vote
1answer
33 views

Is it possible to convert a gpg key to a different encryption algorithm [duplicate]

Maybe the answer to this question is a simple and unequivocal "No", followed by "How can you possibly think that this is possible?". And if I think about it rationally this seems to be the only ...
22
votes
3answers
2k views

What ways are there to verify a self-written protocol?

Before everyone goes yelling: "NEVER DO YOUR OWN CRYPTO", I haven't, technically (I'm still half way), but apart from that I am making a TLS-like protocol, but way lighter. I needed to secure ...
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2answers
77 views

Securing communications in decentralized network of servers

Lets consider the following setup: One has a decentralized network of servers. A single root certificate has been distributed to all servers which has been positively checked as authentic and ...
4
votes
1answer
42 views

Is is possible to avoid internal seeding of a RNG and seed the generator manually using OpenSSL's RAND_bytes()?

I'm trying to write a random number generator with the OpenSSL library. The provided RAND_bytes() function is self-seeding with the /dev/urandom. That's why I am only able to reseed with the ...
5
votes
1answer
86 views

How does combining SHA256 with RIPE-MD160 compare to SHA256 + SHA-3?

Bitcoin stores its addresses as a combined SHA256 + RIPE-MD160 hash. Is it correct to assume this is done to prevent a failure in the algorithm? Since SHA3 was designed to be an alternative to ...
2
votes
1answer
92 views

Plain text password emailed back during registration [duplicate]

I would like to ask if the passwords in the database are not encrypted if during registration I am receiving plain text password with username.
2
votes
0answers
43 views

How does SHA3 (Keccak & SHAKE) compare to SHA2? Should I use non-SHAKE parameters?

Keccak is the winner of the SHA3 competition. Since Keccak is highly customizable (presumably for security/memory/time/speed tradeoffs) there does seem to be some controversy around how Keccak ...
4
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2answers
94 views

Should other processes be running while an iPhone or Android is generating a cryptographically random number?

I need to generate a cryptographically secure random number on iOS and Android. I could use a software approach or leverage the built in OS API for this. In each case, is it better to generate a ...