Need

Secure encryption algorithm using strong elliptic curves

Context

• Usage of Python 3 for general-purpose programming and scripting
• Usage of cryptography for secure data encryption and decryption

Description

Non compliant code

        from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import ec

private_key = ec.generate_private_key(ec.SECP192R1(), default_backend())
data = b"this is some data I'd like to encrypt"
signature = private_key.sign(data, ec.ECDSA(hashes.SHA256()))
        
        

The above code is an example of using an insecure elliptic curve, specifically SECP192R1, for cryptographic operations in a Python application using the cryptography library.

The ec.generate_private_key function is used to generate a private key using the SECP192R1 elliptic curve. This particular curve is considered insecure due to its small key size of 192 bits, which makes it susceptible to attacks that can compromise the security of the encrypted data.

The private_key.sign function is then used to sign some data using the insecure private key and the ECDSA algorithm with SHA256 hashing. The security of this signature is also compromised due to the use of the insecure private key.

In summary, the use of the SECP192R1 elliptic curve in this code makes it vulnerable to cryptographic attacks that can lead to the exposure of sensitive data or the forging of signatures. It is recommended to use a more secure elliptic curve, such as SECP384R1 or SECP521R1, which have larger key sizes and are currently considered secure.

Steps

• Replace the weak elliptic curve (SECP192R1) with a stronger one. A recommended curve is SECP384R1.
• Ensure that the new elliptic curve is supported by the cryptography library.
• Test the updated code to ensure that it works as expected and the encryption is now secure.

Compliant code

        from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import ec

# Use a stronger elliptic curve
private_key = ec.generate_private_key(ec.SECP384R1(), default_backend())
data = b"this is some data I'd like to encrypt"
signature = private_key.sign(data, ec.ECDSA(hashes.SHA256()))
        
        

The original code was using the SECP192R1 elliptic curve, which is considered weak and insecure for encryption. This could potentially lead to vulnerabilities where an attacker could break the encryption and gain access to sensitive data.

The updated code now uses the SECP384R1 elliptic curve, which is much stronger and provides a higher level of security. This curve is recommended for most applications as it provides a good balance between security and performance.

The generate_private_key function is used to generate a private key using the specified elliptic curve. This private key is then used to sign the data using the ECDSA (Elliptic Curve Digital Signature Algorithm) with the SHA256 hash function. This ensures that the data is securely encrypted and can only be decrypted with the corresponding public key.

It's important to note that the cryptography library must support the SECP384R1 elliptic curve. Most modern versions of the library should support this curve, but it's always a good idea to check the documentation or test the code to ensure compatibility.

After updating the code, it's recommended to thoroughly test the encryption and decryption process to ensure that it works as expected and that the encryption is secure. This could involve encrypting some test data, decrypting it with the corresponding public key, and verifying that the decrypted data matches the original data.

References

• 421. Insecure encryption algorithm - Insecure Elliptic Curve