Java is an object-oriented programming language. Java programs are compiled to bytecode and run in a virtual machine (JVM). Java should not be confused with JavaScript; JavaScript is an entirely different programming language.

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EC Schnorr or Ed25519 Java card implementation [migrated]

I am trying to implement ED25519 in java card. Since there are many restrictions with respect to data types and sizes, its becoming tough to implement it, especially curve operations. Is there any ...
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0answers
37 views

Strength of TripleDES (DESede) in Java (Sun JCE)?

I'm introducing Jasypt to a spring-boot project. The default algorithm for storing passwords with it is PBEWithMD5AndDES. Since I've got some reservations on using that cipher, I'm looking into ...
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0answers
17 views

$GF(2^n)$ for $n > 32 $ arithmetics free or opensource java library [migrated]

I need a library implementing the $GF(2^n)$ field arithmetic for a large $n$. I tried BouncyCastle but it provides only $n < 32$.
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1answer
193 views

Should I use RSA encryption since RSA is said to be broken by NSA? [closed]

I am developing a simple web app that uses asymmetric encryption, but I am not sure whether to chose RSA for the reasons mentioned above. What are your suggestions? Also if I decided to go with RSA ...
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1answer
97 views

Implementing AES-CBC (Matasano Crypto Challenge 10)

I am currently doing the Matasano Crypto Challenge to learn a bit about cryptography. In that specific challenge one had to implement AES in CBC mode. I did that and verified that encryption and ...
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1answer
95 views

Which is better? Serialize and then encrypt or Encrypt and then Serialize

Let say in a simple Java program, Considering all the facts, like security and performance, Which is the best way to follow. I tried searching for a answer but proper answer is not out there.
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1answer
47 views

PublicKey Unknown Encoding

I have a public key: ...
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0answers
30 views

ECSchnorr Still getting wrong (hash?) results [closed]

I'm writing Schnorr signature algorithm on elliptic curves. I get instructions from here (page 128) Here's my code ...
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1answer
174 views

Encrypt large data with RSA through blocks in java

I'm working on a communication protocol where a client sends encrypted data to a server. What happens is that in some point, the client creates a symmetric key used to create data digests through the ...
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1answer
98 views

About end to end algorithm SMS from Jo Mehmet Sollihagen Øztarman [closed]

This is a signcryption scheme from End-to-End Data Protection of SMS Messages by Jo Mehmet Sollihagen Øztarman (pdf, section 4.3.1): Public parameters C: an elliptic curve over GF(ph) with p ≥ ...
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1answer
48 views

PKCS5 having no padding

I am using the javax.crypto.Cipher in Java to do AES/CBC/PKCS5Padding encryption. What I am observing is that, if you try to encrypt a Plaintext with no padding, PKCS5 adds another entire block just ...
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1answer
47 views

How exactly is an enigma simulation software supposed to encrypt alphabets?

EDIT: The model I'm trying to make is "Enigma 1". I learned initially about it from a book called "Code Book" and then looked at it in detail from its wikipedia page. The rotor wiring and other ...
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1answer
151 views

How to determine the RSA Private key size from the Public.key file?

Question: How to determine the RSA Private key size from the Public.key file? Just roughly, how big it could be? ...
5
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2answers
423 views

How to verify the integrity of RSA encrypted messages?

I need to encrypt messages using PublicKeyCrypto and send it to the server, where the message should be decrypted. I'm aware of the Padding Oracle Attack and want to apply a server side integrity ...
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1answer
111 views

Converting ECC Code from python to Java. Extended Euclidean Algorithm not working. [closed]

I'm in the process of converting a Python program I found for calculating ECDSA public keypairs from a given private key. In this particular case it's on the Bitcoin curve. ...
0
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2answers
794 views

AES-CTR in BouncyCastle with string key, without IV or salt [closed]

Our team is encrypting data using a javascript snippet. My problem is I'm supposed to parse them back in my Java code. I am having troubles identifying parts of the algorithm. The code says it's CTR ...
2
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2answers
524 views

Using ECB as RSA encryption mode, but encrypted messages are unique

As I understand, ECB should not be used as encryption mode unless you are encrypting single blocks of data which are always unique and only are encrypted once. I have a collection of ids represented ...
0
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1answer
110 views

Rsa Key Exchange Protocol

Moderators: Maybe this question will be move to other sub-forum. My question is Anybody know some link with a tutorial of how implement the RSA key exchange protocol using java for chat comunication?
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1answer
3k views

Is it safe to use PBEWithMD5AndDES?

I'm encrypting some of my (not so much important) files with PBEWithMD5AndDES. Is it a strong method or it can be de-crypt easily without knowing my selected ...
0
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1answer
743 views

decrypt a saml 2.0 response having aes 128 and rsa [closed]

I need to decrypt a saml 2.0 response. But, the response object has reference to aes 128 and rsa algorithms, and I am having hard time in finding a way to decrypt. Below is the structure of the ...
0
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1answer
128 views

Generating cyclic group for Ciphertext-Policy Attribute-Based Encryption [closed]

I am doing Project under the topic CP-ABE.I need to generate a symmetric bilinear group Go of prime order p and with generator g...Then how to choose random elements from Zp....kindly anyone help ...
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2answers
466 views

Generation of a cyclic group of prime order

I am trying to implement a cyclic group generator in Java, but I am running into some issues. In many cryptosystems, the following phrase is expressed during the key generation stage. Let G be ...
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2answers
41 views

Combined message separation

I have two ciphertexts, I suppose that its RC4 with reused key. I have XORed both ciphertexts and obtained message containing combined cleartexts. I suppose that the underlaying messages are written ...
0
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1answer
66 views

Why the data length is shifted 3-bit in MD4 Java implementation? [closed]

In RFC 1320, It is stated that "A 64-bit representation of b (the length of the message before the padding bits were added) is appended to the result of the previous step. In the unlikely event that b ...
3
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2answers
947 views

PRNG determinism (and java.security.SecureRandom)

Looking at getDefaultPRNG() in java.security.SecureRandom makes me very unsure about how to use it. On my desktop, it uses sun.security.provider.NativePRNG, which reads from ...
10
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1answer
2k views

Why there are limitations on using encryption with keys beyond certain length?

I am writing a java program to encrypt a message using 256-bit AES encryption, but I am getting illegal key size error, I have read that I have to use some JCE ...
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0answers
129 views

java.util.Random and Dice Rolls

For this question, a dice roll will be considered two 6 six sided dice, to give a possible output of 2-12. Given a java.util.Random instance r, the output of one roll would be: ...
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1answer
1k views

What Java actually stores inside Keystore when generating Keys?

When we use Keytool to generate a Keystore to store Private/Public keys, what Java actually stores inside the Keystore file ? I ...
1
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1answer
694 views

Java: How to handle authenticated encryption for big files

First I need to mention that I can't use BouncyCastle to implement this solution. I have to encrypt files into the file system. Those files are not going to be tranfered over the wire to any other ...
0
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1answer
219 views

Bouncy Castle and Salsa 20 [closed]

I want to use Salsa 20 in Java, so I downloaded Bouncy Castle, and... it makes no sense to me. I've got it working, but most of my choices were essentially random. But I can't see there anything ...
0
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1answer
354 views

Bouncy Castle elliptic curve from explicit parameters (E-521)

I'd like to use a curve that's not included in the Bouncy Castle EC named curves spec, specifically E-521. According to the BC javadocs, you need a few values in order to do this: q, a, and b for the ...
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2answers
342 views

Why would an RSA library tell me that the public key must be at least 512 bits in size?

I'm trying to interoperate with a web service by reverse-engineering it. Currently, when sending a POST request, it encrypts the form data one-by-one with a 'RSA' function. But it's rather weird as ...
1
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0answers
437 views

Elliptic curves in java

I am writing you because I want to implement the DPS signature with elliptic curves in Java. I found this library http://docs.oracle.com/javase/7/docs/api/java/security/spec/package-summary.html which ...
2
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3answers
159 views

Does 3-DES take approximately the same time to encrypt 1B and 1KB?

I am using 3-DES to encrypt some data in Java. I decided to run some tests and plot some graphics to decide how to optimally pack data for its encryption (see how encryption/decryption time behave ...
2
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2answers
173 views

Storing encryption key

It's my first time using stackexchange! So, I am doing a password manager in Java. But now I am VERY confused because of the encryption. There will be the program login, where the user types its ...
2
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2answers
1k views

What curve and key length to use in ECDSA with BouncyCastle

I'm developing a client/server system in Java which is not interacting with third party software, so I don't have to worry about compatibility. At a certain point, I need the client and server to ...
1
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1answer
211 views

The relationship between the key length and encrypt time in Xor algorithm?

I did work on the encryption algorithm and the decryption using the XOR method noticed that when more the key length, the less time spent on encryption and decryption. I have two questions in ...
3
votes
1answer
975 views

Mapping of message onto elliptic curve and reverse it

I would like to perform a variant of Elliptic Curve ElGamal in java using the BouncyCastle libraries. I currently face the difficulty of mapping a message $m$ onto the elliptic curve $E_p$. I have so ...
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1answer
134 views

Adding “salt” to “doHash” function in Java [closed]

For one of my university projects I am being asked to "Improve the code to satisfy the pre-image resistance requirement." Basically the program is a basic encryption server system, and when I type a ...
2
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2answers
93 views

SHA-256 Wrong registers

I have a problem with my sha256 java implementation. The registers (a…h) are correct until j=24; ...
1
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1answer
550 views

Encrypting a payload for transmission over HTTP. AES256 with PBKDF2

I've done some reading about implementing AES256 and deriving a key from a password. If I understand correctly: I want to generate a new salt (for the key) and a new IV (for the encrypted message) ...
1
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1answer
647 views

Z*p Generator (Cyclic Group) in java

I am trying to implement ElGamal in java without using the in-built libraries. The problem occurs when I am trying to find the generators of the number(in this case 11). Everything works perfectly ...
3
votes
1answer
355 views

Predicting Java's PRNG using partial output

I have a program (a game) that uses Java's nextInt function with parameter 0x10000 to get a random 16-bit number. Java's ...
1
vote
1answer
63 views

byte length and offset for k3d3/ed25519 byte[] variables?

I've discovered for myself that java's BigInteger is very slow, so I'm trying to weakly optimize this java implementation of ed25519 which I will fork and post if ...
4
votes
1answer
361 views

How can k3d3/ed25519-java's performance be improved?

I tried asking this on stackoverflow because I thought it might be a simple coding question and didn't want to clutter up this amazing stack, but I received no responses. CodesInChaos showed me that ...
4
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1answer
949 views

Java's SecureRandom & plaintext attack?

Java's SecureRandom is meant to be cryptographically secure, and I know part of that means that the output should not be usable to predict further output. Though, ...
1
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1answer
290 views

Generate keys with k3d3 / ed25519-java

I'm trying to use a java implementation of ed25519. In the code, I can't find any functions that generate keys. My experience with cryptography is limited to about three weeks of asking questions on ...
3
votes
1answer
2k views

Is it true for Java that the transformation mode and padding is ignored when using RSA?

Consider GregS's comment to this question (more specific to bouncycastle's provider implementation): http://stackoverflow.com/questions/11717646/bouncycastle-rsa-key-size-and-padding The mode, ...
6
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3answers
6k views

PBKDF2WithHmacSHA512 Vs. PBKDF2WithHmacSHA1

I'm working on a Java authentication subsystem that specs the storage of passwords in the DB as PBKDF2-generated hashes, and I'm now trying to decide whether I ...
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0answers
461 views

RSA Attack with some known values

There is an RSA implementation which I need to attack to get the encrypted messages. Some of the values are known. Plain text value for input. So if I enter a message, say it "A", the plain text is ...