Questions tagged [cryptography]

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 password storage) and digital signatures (provable integrity and authenticity with non-repudiation).

Filter by
Sorted by
Tagged with
0
votes
0answers
111 views

Why does linux cryptsetup use PBKDF2 instead of bcrypt?

I've noticed that linux's cryptsetup utility by default uses the PBKDF2 for a key derivative function (KDF) versus using bcrypt, when bcrypt has more resistance to brute forcing from gpus. Why would ...
0
votes
0answers
63 views

How to determine the encoding used when you have the data not the source code [duplicate]

The source code converts the data as below: 00000 - 62F0CBA67EA6A2C03D399A1B06D82787CB46480370FDA0C1CF5016E59A61F0A6 000000 - F657FC2120036C2EF29AF87E4194539B1728AB2F204676E413C6FFD5970453B9 ...
0
votes
2answers
146 views

How do you use a public key to encrypt a string

I am oversimplifying but I understand that a public key is the product of two large prime numbers. In essence as long as the private key is kept private, the owner knows something that the outside ...
0
votes
1answer
61 views

How to identify the right hash from a list of salts and pre-given password during authentication?

I apologize for being naive, but I only recently started learning about cryptography and how to go about the security online. From what I've gathered, the safest-without-sacrificing-efficiency way ...
33
votes
8answers
116k views

Why is WPA Enterprise more secure than WPA2?

In personal mode WPA2 is more secure than WPA. However, I have read that WPA Enterprise provides stronger security than WPA2 and I am unsure exactly how this is achieved.
105
votes
5answers
24k 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 "...
10
votes
1answer
723 views

OpenSSL EVP aes_256_cbc Initialization Vector Size

I'm looking at the crypto library examples (programmed in c) provided for OpenSSL EVP on OpenSSL Wiki. Their example for a 128 bit Initialization Vector is as follows: /* A 128 bit IV */ unsigned ...
0
votes
3answers
88 views

Is it possible to build a partial search mechanism on hashed values? [closed]

I am hashing some sensitive values to support search mechanism as decrypting the values at run-time would be time consuming. I'm using SHA-512 with salt. For now, things look good. I have the hashes ...
0
votes
0answers
44 views

CSP/KSP module for MacOS

My company developed a custom Key Storage Provider for Microsoft CAPI so that CNG-using Windows apps can perform signatures using a remote signature service. I would like to know if there is support ...
33
votes
5answers
8k views

SSH - If Eve has the passphrase and public key, can she derive the private key?

I have used ssh-keygen for creating an RSA 4096-bit SSH private and public key pair. I used a passphrase for the private key. If an attacker, Eve, knows the passphrase in addition to the public key: ...
-2
votes
1answer
133 views

What is ECC / HECC, how does it differ from asymmetric encryption?

I'm relatively new to cryptography, and I would like to know what Elliptic Curve Cryptography and Hyper Ellipic Curve Cryptography (HECC) are, and where they are intended to be used. I have read ...
1
vote
2answers
1k views

Which keystore type is good for java / Tomcat based applications

The application is based on Java and Tomcat server. Which type of keystore is better ? does JKS or PCKS12 ? I understand JDK keytool by default creates JSK type then for which uses-cases one should ...
3
votes
2answers
1k views

How is an SSH public key fingerprint calculated?

I have a public key as the following 64 bytes encoded string AAAAB3NzaC1yc2EAAAADAQABAAABAQDapfZSmaVBZimVC7YAsISc+fKzuhbVmmbJNYELWov4ZVbdbFxf790xC0sKQTmbe1iDt25DdsandggApKZh6yvWD0Li5RV+...
6
votes
3answers
1k views

Patent free symmetric-only key exchange protocols?

I am working with a networked embedded device with AES-128 and no public key cryptography (1KB RAM, 8KB flash). At install, the device is pre-loaded with a longterm AES-128 key known also to the ...
12
votes
1answer
2k views

How to get a 'million rounds of PKCS#8 + PBKDF2' with OpenSSL?

I posted this question Is a passphrase-protected SSH private key susceptible to a dictionary attack? a few days back. An excerpt from the final answer: With PKCS#8 + PBKDF2 and one million rounds ...
0
votes
1answer
155 views

Deciphering ciphertext with an unknown key and algorithm [closed]

How can I get started on understanding how to decipher this ciphertext when I don't know the algorithm or key used? TDcbY xqCa NeAA OsWMirK FNFOm bYRUYAkxl,  tqwl  axZU  XTaLrBSFv OI G vWjBZyqhz.  ...
0
votes
0answers
41 views

How ECDH Implement in Microservices

I have a problem when I want to encrypt decrypt data by use the same key in every services.I use ECDH Method to encrypt decrypt data between client and server. I have a exchangeKey service to gen Key ...
10
votes
2answers
17k views

How can you check if a private key and certificate match in OpenSSL with ECDSA?

I know how to do this with RSA keys (see this article: Determine if private key belongs to certificate?) however I do not know how to do this for ECDSA certificate / key pairs. With RSA keys, the ...
0
votes
0answers
45 views

Convert openssl private key to openssh private key [duplicate]

I have an openssl format private key that i need to use as a host key for openssh connection.How can i convert the openssl format private key to openssh formatted private key using ssh-keygen.I have ...
8
votes
3answers
3k views

Can a zero knowledge proof of voting be made using a trusted auth server (without client side crypto)?

Questions: Can one implement a secure voting system having all the features described below? e.g. without disclosing any individual's vote to the government server (or the third party), preserving ...
0
votes
2answers
340 views

Understanding AES Keys and Passphrases

I am trying to get my head around how AES works and in particular I have queries around the key generation and 'passphrases'. My understanding is that AES has a 128 bit block size but the key length ...
35
votes
5answers
26k 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 has more advantages than another?
0
votes
1answer
172 views

Understand the “Windows Key Store”

I work in a enterprise environment and I often hear the use of the "Windows Key Store" to store various keys including symmetric. I do understand there is a "Windows Certificate Store" which as the ...
0
votes
0answers
55 views

Generate & secure private keys in a private network

I have seen latest mobile authentication solution where private key is generated and kept securely in a Secure Enclave/TrustZone and public key is sent to authentication server on a cloud. During User ...
1
vote
1answer
90 views

What's the goal behind signing a CRL with an old certificate key?

I was reading a CPS/CP for a CA, and it mentioned that there's a possibility after rekey that you can still use the old key to sign CRLs of the old end user certificates verified by the old CA ...
2
votes
4answers
234 views

Are multiple encrypted containers with the same passphase containing the same files a cryptographic risk?

Situation as follows: Let's assume two (or more) containers, encrypted using the same passphrase. They will contain the same files. So their content is identical. However, the containers themselves ...
0
votes
1answer
390 views

Validating a RSA public key

A a total noob to cryptography. Situation: Given only the public_key i need to know if it is valid; in that, if i use it to encrypt say a form submission, the form data will actually be encrypted. ...
17
votes
5answers
5k views

Hashcash, is this really used?

I just heard about this term, is it really used? The concept does not seem new, is it used and/or implemented in current technologies?
9
votes
4answers
4k views

Do keyfiles actually add any meaningful security in the presence of strong passwords?

In the context of protecting access to local encrypted files or devices against a determined (and competent) adversary, is there any reason to believe that the use of a key file actually presents a ...
1
vote
2answers
127 views

How do you use initialization vector? [duplicate]

My application needs to store some sensitive information. I want to encrypt the data before I store it. At some point in the future, I want to be able to read and decrypt all the data. For a ...
20
votes
2answers
13k views

What is the difference between DH and DHE?

I have been reading Bulletproof SSL and TLS Diffie Hellman is a key exchange mechanism, in which each of server and client share secret i.e. gx and gy respectively with each other where g is ...
0
votes
1answer
94 views

For encrypted chat app, how can I store sent messages so that they are encrypted but still can be viewed by the sender?

Actual implimentaton will be in android but this is more about general security than actual implimentaton details. I'm making an end-to-end encrypted chat app and I know that in order to send ...
189
votes
5answers
65k views

Recommended # of iterations when using PKBDF2-SHA256?

I'm curious if anyone has any advice or points of reference when it comes to determining how many iterations is 'good enough' when using PBKDF2 (specifically with SHA-256). Certainly, 'good enough' is ...
0
votes
1answer
66 views

How to authorize access to a resource when requested with CORS and validate the origin?

I'll try to make the explanation simple and to the point (keyword try). And if that's not sufficient, then maybe I can expand on the question. Imagine two sites: resources.example.com and www.example....
18
votes
4answers
4k views

At what point does adding more iterations to PBKDF2 provide no extra security?

If my true passphrase is used only to generate a hash which is used as the cipher's actual key, doesn't that mean it's possible to try and brute force the cipher itself? I know it would take an ...
0
votes
0answers
54 views

Is it safe to use Giphy API keys in public Github repo?

I am making a game of which one of the hidden features is displaying a GIF from Giphy at a fixed command. For this, I am using Giphy API, hosting the game as a website on Github Pages with a public ...
251
votes
11answers
62k views

Why shouldn't we roll our own?

Why shouldn't we create our own security schemes? I see a lot of questions around here about custom crypto and custom security mechanisms, especially around password hashing. With that in mind, I'm ...
0
votes
1answer
147 views

How do digital signatures work - beginner's explanation?

I'm new to cryptography, and I'm confused about digital signatures. How do they work? Please illustrate with an example in a way that a beginner can understand.
3
votes
1answer
5k views

Bitdefender Antivirus SSL Cert substitution

I am using Bitdefender AV 2013 ed and I have noticed that when the Scan SSL is enabled in the configuration BD will use a local certificate, as mentioned here. This modifies the cert chain with BD as ...
3
votes
1answer
358 views

Does revoking a certificate result in revocation of its key?

If I request my identity certificate to be revoked for any reason other than key compromise, would the private key also be revoked in result?
2
votes
2answers
232 views

SSH key based login is not vulenerable to MiTM attack. Is it true?

I read somewhere that when using key based login instead of a password based login, it is not possible for a Man-in-the-Middle attack to happen. This question is not about what is being more secure: ...
0
votes
2answers
2k views

Getting RSA private key from prime1, modulus and publicExponent [duplicate]

I am doing a hacking challenge but I don't manage to know how to decrypt the private key from the public key and the given private key "prime1" parameter. I've seen a private key is composed of : ...
-2
votes
3answers
260 views

Is this adaptation of using a One Time Pad safe?

For example, lets say there are two people named, Bob, and Jim. Bob wants to send Jim a long secret message, and he decides to use a OTP to encrypt his message. Both Bob and Jim know a secret ...
43
votes
5answers
44k views

How to achieve non-repudiation?

If I have a message that I need to send to another person, how do I achieve non repudiation ? Is digitally signing the message sufficient ?
1
vote
1answer
72 views

How to protect file integrity and history containing counters

I would like to create a solution that would sign the data and will have a increasing counter so I can track the number of signatures. One of the requirement is to have an increasing order of ...
0
votes
3answers
173 views

How is the strength of a key/Password determined

I was reading about the Principle of Key Sizes and came across this table: The deduction I made off this is that after a certain key size, increase in a single bit causes Time required for search to ...
4
votes
2answers
395 views

How does master secret calculates in encryption protocol used by WhatsApp?

I have read the algorithm behind WhatsApp encryption in this document. I can not understand how the initiator calculates a master secret. The initiator calculates a master secret as: ...
0
votes
1answer
73 views

Determine relation between many keys

I have many keys of short length (6 bytes) and I know some factors that might be used to calculate them. I know for sure that the can be obtained with the given information. Since the keys are very ...
8
votes
5answers
748 views

Who SHOULD write crypto code?

I've seen a lot of questions and answers acknowledging the dangers of inventing your own crypto algorithms — and even of implementing proven algorithms yourself. And, I don't disagree. I might ...
2
votes
0answers
232 views

OpenPGP smartcards compromised by blackhat 2015 simcard hack?

This blackhat was a new sidechannel attack in the SIM-card AES encryption announced. I am currently using the OpenPGP smart/SIM-card version 2.1 to store my PGP-private keys, which is the same model ...