Verify Signature

---

Transaction Signature Verification

Parameters

Parameter	Type	Description
public_key	str	Public keys as hexadecimal string.
msg	str	Message used to verify the signature with public key.
signature	str	Signature to be verified with public key and message.

Example Usage

from pypergraph import KeyStore

valid_signature = KeyStore().verify(public_key="e123...", msg="...", signature="f123...")

if not valid_signature:
    print("Invalid signature.")
else:
    print("Valid signature.)

Lifecycle

import hashlib

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives.asymmetric.utils import Prehashed
from cryptography.exceptions import InvalidSignature

@staticmethod
def verify(public_key: str, msg: str, signature: str) -> bool:
    """
    Verify is the signature is valid.

    :param public_key:
    :param msg: Hex format
    :param signature:
    :return: True or False
    """
    # TODO
    # Compute SHA512 digest of the hex string's UTF-8 bytes and truncate
    sha512_digest = hashlib.sha512(msg.encode("utf-8")).digest()[:32]
    print(public_key)
    # Step 2: Load public key from hex
    public_key_bytes = bytes.fromhex(public_key)
    if len(public_key_bytes) == 65:
        public_key_bytes = public_key_bytes[1:] # Remove 04
    if len(public_key_bytes) != 64:
        raise ValueError("Public key must be 64 bytes (uncompressed SECP256k1).")

    # Split into x and y coordinates (32 bytes each)
    x = int.from_bytes(public_key_bytes[:32], byteorder="big")
    y = int.from_bytes(public_key_bytes[32:], byteorder="big")

    # Create public key object
    public_numbers = ec.EllipticCurvePublicNumbers(x, y, ec.SECP256K1())
    public_key = public_numbers.public_key(default_backend())

    # Step 3: Verify the signature
    try:
        public_key.verify(
            bytes.fromhex(signature),
            sha512_digest,
            ec.ECDSA(Prehashed(hashes.SHA256()))  # Treat digest as SHA256-sized
        )
        return True
    except InvalidSignature:
        return False

---

Data Signature Verification

Parameters

Parameters	Type	Description
public_key	str	Public keys as hexadecimal string.
encoded_msg	str	Message used to verify the signature with public key. Important: Encode the message according to the method used when signing the data.
signature	str	Signature to be verified with public key and message.

Example Usage

from pypergraph import KeyStore()

import time
import json

from pypergraph import KeyStore

pk = KeyStore.get_private_key_from_mnemonic("abandon ...")
pub_k = KeyStore.get_public_key_from_private(pk)
address = KeyStore.get_dag_address_from_public_key(pub_k)

# Sample data to sign
water_and_energy_usage = {
    "address": address,
    "energyUsage": {
        "usage": 7,
        "timestamp": int(time.time() * 1000),
    },
    "waterUsage": {
        "usage": 7,
        "timestamp": int(time.time() * 1000),
    },
}

# Custom encoding function example
def encode(data: dict) -> str:
    return json.dumps(data, separators=(',', ':'))

# Generate a signature and hash for the custom data
signature, hash_value = KeyStore().data_sign(
    private_key=pk,
    msg=water_and_energy_usage,
    prefix=False,
    encoding=encode
)

# Same encoding as used to sign
encoded_msg = encode(water_and_energy_usage)
valid_signature = KeyStore().verify_data(public_key=pub_k, encoded_msg=encoded_msg, signature=signature)

if not valid_signature:
    print("Invalid signature.")
else:
    print("Valid signature.")