Converting ECDSA Signature to DER Encoded Format in Python

In this article, we will explore the process of converting an ECDSA signature from a hexadecimal string to a DER (Distinguished Encoding Rules) encoded format using Python’s ecdsa and hashlib libraries.

Required Libraries

• ecdsa: for generating and verifying ECDSA signatures

• hashlib: for hashing and signing the input data

Sample Code

import ecdsa 
Importing the ECDSA library

import hashlib 
Importing the hash library

from ecc import ec 
Importing the ecc module from the Ecc library



Define the ECDSA key and signature

pubKey = b'your_pub_key_hex_here'

signature = b'signature_hex_here'



Create a new VerifyingKey object using the provided public key

vk = ecdsa.VerifyingKey.from_string(bytes.fromhex(pubKey), curve=ecdsa.SECP256k1)



Define the SHA-256 hash function and an instance of the hashlib library

sha256_hash = hashlib.sha256()



Sign the input data using ECDSA (replace with your own signature)

signing_data = bytearray()

vk.sign(signature, signing_data, sha256_hash)



Convert the DER encoded signature to a hexadecimal string

der_encoded_signature = bytes(signing_data).hex()


if vk.verify(bytes.fromhex(signature), bytes.fromhex(der_encoded_signature), hashlib.sha256, sigdecode=ecdsa.SigningHash.DER) == True:

    print("Successful verification!")

else:

    print("Verification failed!")

Explanation

• We first import the necessary libraries: ecdsa for generating and verifying ECDSA signatures and hashlib for hashing and signing.

• We define the ECDSA key (public and private) and the signature in hexadecimal format.

• We create a new VerifyingKey object using the provided public key.

• We define the SHA-256 hash function and an instance of the hashlib library to sign the input data using ECDSA.

• We use the vk.sign() method to convert the DER encoded signature to a hexadecimal string, which represents the DER-encoded format.

• We verify the signature by comparing it with the original signature using the vk.verify() method. If they match, we print “Verification successful!”. Otherwise, where print “Verification failed!”.

Important Notes

• Make sure you replace 'your_pub_key_hex_here' and 'signature_hex_here' with your actual public key and signature in hexadecimal format.

• The ecdsa.SigningHash.DER flag is used to encode the signature in DER format. This is a standard encoding scheme for ECDSA signatures.

• You may need to adjust the code according to your specific requirements or handle errors differently.

By following this example, you should be able to successfully convert an ECDSA signature from hexadecimal to DER encoded format using Python’s ecdsa and hashlib libraries.

ETHEREUM SIMPLE ADDRESS