Need

Implementation of secure elliptic curves for encryption

Context

• Usage of Dart for building cross-platform mobile, web, and desktop applications
• Usage of cryptoutils for cryptographic operations

Description

Non compliant code

        import 'package:cryptoutils/cryptoutils.dart';

void main() {
  var data = "Sensitive Information";
  var privateKey = "privateKey";

  // Using weak elliptic curve - secp112r1
  var ecdsa = ECDomainParameters('secp112r1');

  var signer = Signer("SHA-1/ECDSA");

  PrivateKeyParameter privateKeyParam = 
    PrivateKeyParameter(ecdsa.privateKeyFromBigInt(Utils.createUint8ListFromHexString(privateKey)));

  signer.init(true, privateKeyParam);

  ECSignature signature = signer.generateSignature(Uint8List.fromList(data.codeUnits));
  print("Signature: ${signature.r}, ${signature.s}");
}
        
        

The above code is an example of a security vulnerability related to the use of weak elliptic curve cryptography. The problem lies in the use of the secp112r1 elliptic curve, which is considered insecure due to its small size.

In the code, we are encrypting some sensitive data using the Elliptic Curve Digital Signature Algorithm (ECDSA). The ECDomainParameters object is created using the secp112r1 curve. This curve is known to be weak and vulnerable to attacks, which means that an attacker could potentially decrypt the sensitive data.

The PrivateKeyParameter object is created using the private key derived from the weak curve. The signer object is then initialized with this weak private key.

Finally, the sensitive data is signed using the signer's generateSignature method. The resulting signature is then printed out.

In summary, the use of a weak elliptic curve ( secp112r1) in this code makes the encryption of the sensitive data insecure. An attacker could exploit this weakness to decrypt the data.

Steps

• Replace the weak elliptic curve 'secp112r1' with a stronger one such as 'secp256r1'.
• Replace the SHA-1 hash function with a more secure one such as SHA-256 or SHA-3.
• Ensure that the private key is securely generated and stored, not hardcoded in the code.
• Consider using a library or framework that provides secure defaults to avoid these types of mistakes.

Compliant code

        import 'package:cryptoutils/cryptoutils.dart';

void main() {
  var data = "Sensitive Information";
  
  // Generate a secure private key
  var privateKey = generateSecurePrivateKey();

  // Using a stronger elliptic curve - secp256r1
  var ecdsa = ECDomainParameters('secp256r1');

  var signer = Signer("SHA-256/ECDSA");

  PrivateKeyParameter privateKeyParam = 
    PrivateKeyParameter(ecdsa.privateKeyFromBigInt(Utils.createUint8ListFromHexString(privateKey)));

  signer.init(true, privateKeyParam);

  ECSignature signature = signer.generateSignature(Uint8List.fromList(data.codeUnits));
  print("Signature: ${signature.r}, ${signature.s}");
}

Uint8List generateSecurePrivateKey() {
  // Implement a secure method to generate a private key
}
        
        

The original code was using a weak elliptic curve 'secp112r1' for encryption, which is not secure. The updated code now uses a stronger elliptic curve 'secp256r1'. This provides a higher level of security and makes it more difficult for attackers to break the encryption.

The original code was also using the SHA-1 hash function, which is considered insecure due to vulnerabilities that allow for collision attacks. The updated code uses the SHA-256 hash function, which is currently considered secure against all known practical attacks.

The private key was hardcoded in the original code, which is a security risk as anyone with access to the code would also have access to the private key. The updated code includes a placeholder function generateSecurePrivateKey() for generating a secure private key. This function should be implemented to generate a secure private key and store it securely.

It's important to use libraries or frameworks that provide secure defaults to avoid these types of mistakes. Always keep your libraries up to date and follow best practices for secure coding.

References

• 421. Insecure encryption algorithm - Insecure Elliptic Curve