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Insecure encryption algorithm - DSA

Need​

Implementation of a secure encryption algorithm

Context​

  • Usage of Scala for building scalable and high-performance applications
  • Usage of KeyPairGenerator for generating cryptographic key pairs in Java security
  • Usage of java.security.SecureRandom for generating secure random numbers
  • Usage of java.security.Signature for cryptographic signature generation and verification

Description​

Non compliant code​

import java.security.KeyPairGenerator
import java.security.SecureRandom
import java.security.Signature

object DsaEncryption {
  def main(args: Array[String]) {
    val keyGen = KeyPairGenerator.getInstance("DSA")
    val secrand = SecureRandom.getInstance("SHA1PRNG", "SUN")
    keyGen.initialize(1024, secrand)
    val pair = keyGen.generateKeyPair()
    val priKey = pair.getPrivate()
    val pubKey = pair.getPublic()

    val sig = Signature.getInstance("SHA1withDSA", "SUN")
    sig.initSign(priKey)

    val str = "This is an insecure DSA encryption"
    val strByte = str.getBytes("UTF8")
    sig.update(strByte)

    val signature = sig.sign()
  }
}

The above code represents a scenario where the DSA (Digital Signature Algorithm) insecure encryption algorithm is being used in a Scala backend application using the Play framework.

The KeyPairGenerator.getInstance("DSA") is used to generate a pair of keys for the DSA. A SecureRandom instance is created with the SHA1PRNG algorithm. This instance is used to initialize the KeyPairGenerator with a key size of 1024.

Then, a Signature object is created with the SHA1withDSA algorithm. The private key from the pair is used to initialize this Signature object for signing.

A string message "This is an insecure DSA encryption" is converted to bytes and updated to the Signature object. Finally, the sign() method is used to generate the signature of the updated data.

The vulnerability lies in the usage of the DSA algorithm for encryption. DSA is considered insecure due to its susceptibility to various attacks, such as timing attacks and fault attacks. Moreover, it's not recommended to use a key size of 1024 for encryption as it's considered weak. Modern standards recommend a key size of at least 2048 bits for RSA and DSA.

Steps​

  • Replace the use of DSA encryption algorithm with a more secure algorithm, such as RSA or ECDSA.
  • Use a cryptographically secure random number generator, such as SecureRandom, for generating the key pair.
  • Increase the key size to a more secure value, such as 2048 bits or higher.
  • Use a stronger hashing algorithm, such as SHA-256, instead of SHA-1.
  • Ensure that the encryption algorithm and parameters are compliant with the latest security standards and recommendations.
  • Regularly update the encryption libraries and dependencies to stay up-to-date with the latest security patches and improvements.

Compliant code​

import java.security.KeyPairGenerator
import java.security.SecureRandom
import java.security.Signature

object SecureEncryption {
  def main(args: Array[String]) {
    val keyGen = KeyPairGenerator.getInstance("RSA")
    val secrand = SecureRandom.getInstanceStrong()
    keyGen.initialize(2048, secrand)
    val pair = keyGen.generateKeyPair()
    val priKey = pair.getPrivate()
    val pubKey = pair.getPublic()

    val sig = Signature.getInstance("SHA256withRSA")
    sig.initSign(priKey)

    val str = "This is a secure RSA encryption"
    val strByte = str.getBytes("UTF8")
    sig.update(strByte)

    val signature = sig.sign()
  }
}

The above code is a secure version of the previously insecure DSA encryption. Here are the changes made:

  1. Encryption Algorithm: The insecure DSA encryption algorithm has been replaced with the more secure RSA encryption algorithm. This is done by changing the argument of KeyPairGenerator.getInstance() from "DSA" to "RSA".

  2. Random Number Generator: The SecureRandom.getInstanceStrong() method is used to get a cryptographically strong random number generator. This is more secure than the previously used SecureRandom.getInstance("SHA1PRNG", "SUN").

  3. Key Size: The key size has been increased from 1024 bits to 2048 bits. This is done by changing the first argument of keyGen.initialize() from 1024 to 2048.

  4. Hashing Algorithm: The SHA-1 hashing algorithm has been replaced with the stronger SHA-256 algorithm. This is done by changing the argument of Signature.getInstance() from "SHA1withDSA" to "SHA256withRSA".

By making these changes, the encryption process becomes more secure and resistant to cryptographic attacks. It's also important to regularly update the encryption libraries and dependencies to stay up-to-date with the latest security patches and improvements.

References​

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