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ritmex-bot/docs/edgex/edgex-python-sdk-main/edgex_sdk/internal/starkex_signing_adapter.py
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"""
StarkEx signing adapter for the EdgeX Python SDK.
This module provides an implementation of the signing adapter interface
that uses the StarkWare cryptographic primitives for signing operations.
"""
import binascii
import math
import secrets
from typing import List, Tuple
from .signing_adapter import SigningAdapter
from ..crypto.pedersen_hash import pedersen_hash_bytes
# StarkEx curve parameters
FIELD_PRIME = 0x800000000000011000000000000000000000000000000000000000000000001
ALPHA = 1
BETA = 0x6f21413efbe40de150e596d72f7a8c5609ad26c15c915c1f4cdfcb99cee9e89
EC_ORDER = 0x800000000000010ffffffffffffffffb781126dcae7b2321e66a241adc64d2f
N_ELEMENT_BITS_ECDSA = math.floor(math.log(FIELD_PRIME, 2))
assert N_ELEMENT_BITS_ECDSA == 251
# Generator point for the Stark curve
EC_GEN = (
0x1ef15c18599971b7beced415a40f0c7deacfd9b0d1819e03d723d8bc943cfca,
0x5668060aa49730b7be4801df46ec62de53ecd11abe43a32873000c36e8dc1f
)
class StarkExSigningAdapter(SigningAdapter):
"""StarkEx implementation of the signing adapter interface."""
def sign(self, message_hash: bytes, private_key: str) -> Tuple[str, str]:
"""
Sign a message hash using a private key.
Args:
message_hash: The hash of the message to sign
private_key: The private key as a hex string
Returns:
Tuple[str, str]: The signature as (r, s) hex strings
Raises:
ValueError: If the private key is invalid or the signing fails
"""
try:
# Validate private key format
binascii.unhexlify(private_key)
except binascii.Error:
raise ValueError("Invalid private key hex string")
# Convert message hash to integer
msg_hash_int = int.from_bytes(message_hash, byteorder='big')
# Ensure the message hash is in the valid range
# Use the same modulus as the Golang SDK (EC_ORDER, which is starkcurve.N)
msg_hash_int = msg_hash_int % EC_ORDER
# Convert private key to integer
priv_key_int = int(private_key, 16)
# Ensure the private key is in the valid range
# For testing purposes, we'll just take the modulus
priv_key_int = priv_key_int % EC_ORDER
if priv_key_int == 0:
priv_key_int = 1
# Sign the message
r, s = self._sign(msg_hash_int, priv_key_int)
# Convert r and s to hex strings
r_hex = format(r, '064x')
s_hex = format(s, '064x')
return r_hex, s_hex
def get_public_key(self, private_key: str) -> str:
"""
Get the public key from a private key.
Args:
private_key: The private key as a hex string
Returns:
str: The public key as a hex string
Raises:
ValueError: If the private key is invalid
"""
try:
# Validate private key format
binascii.unhexlify(private_key)
except binascii.Error:
raise ValueError("Invalid private key hex string")
# Convert private key to integer
priv_key_int = int(private_key, 16)
# Ensure the private key is in the valid range
# For testing purposes, we'll just take the modulus
priv_key_int = priv_key_int % EC_ORDER
if priv_key_int == 0:
priv_key_int = 1
# Get the public key
public_key = self._private_to_stark_key(priv_key_int)
# Convert public key to hex string
public_key_hex = format(public_key, '064x')
return public_key_hex
def verify(self, message_hash: bytes, signature: Tuple[str, str], public_key: str) -> bool:
"""
Verify a signature using a public key.
Args:
message_hash: The hash of the message
signature: The signature as (r, s) hex strings
public_key: The public key as a hex string
Returns:
bool: Whether the signature is valid
"""
try:
# Convert message hash to integer
msg_hash_int = int.from_bytes(message_hash, byteorder='big')
# Ensure the message hash is in the valid range
# Use the same modulus as the sign method (EC_ORDER)
msg_hash_int = msg_hash_int % EC_ORDER
# Convert signature components to integers
r_int = int(signature[0], 16)
s_int = int(signature[1], 16)
# Ensure r and s are in the valid range
if not (1 <= r_int < 2**N_ELEMENT_BITS_ECDSA and 1 <= s_int < EC_ORDER):
return False
# Convert public key to integer
pub_key_int = int(public_key, 16)
# Verify the signature
return self._verify(msg_hash_int, r_int, s_int, pub_key_int)
except Exception:
return False
def pedersen_hash(self, elements: List[int]) -> bytes:
"""
Calculate the Pedersen hash of a list of integers.
This method now uses the full Pedersen hash implementation
that follows StarkWare's specification.
Args:
elements: List of integers to hash
Returns:
bytes: The hash result
Raises:
ValueError: If the calculation fails
"""
try:
# Use the full Pedersen hash implementation
return pedersen_hash_bytes(*elements)
except Exception as e:
raise ValueError(f"Failed to calculate Pedersen hash: {str(e)}")
def _sign(self, msg_hash: int, priv_key: int) -> Tuple[int, int]:
"""
Sign a message hash using a private key.
Args:
msg_hash: The hash of the message to sign as an integer
priv_key: The private key as an integer
Returns:
Tuple[int, int]: The signature as (r, s) integers
"""
# Choose a valid k. In our version of ECDSA not every k value is valid,
# and there is a negligible probability a drawn k cannot be used for signing.
# This is why we have this loop.
while True:
# Use random nonce generation like the Go SDK
k = self._generate_random_k()
# Cannot fail because 0 < k < EC_ORDER and EC_ORDER is prime.
x = self._ec_mult(k, EC_GEN)[0]
# DIFF: in classic ECDSA, we take int(x) % n.
r = int(x)
if not (1 <= r < 2**N_ELEMENT_BITS_ECDSA):
# Bad value. This fails with negligible probability.
continue
if (msg_hash + r * priv_key) % EC_ORDER == 0:
# Bad value. This fails with negligible probability.
continue
w = self._div_mod(k, msg_hash + r * priv_key, EC_ORDER)
if not (1 <= w < 2**N_ELEMENT_BITS_ECDSA):
# Bad value. This fails with negligible probability.
continue
s = self._inv_mod_curve_size(w)
return r, s
def _verify(self, msg_hash: int, r: int, s: int, public_key: int) -> bool:
"""
Verify a signature using a public key.
Args:
msg_hash: The hash of the message as an integer
r: The r component of the signature as an integer
s: The s component of the signature as an integer
public_key: The public key as an integer
Returns:
bool: Whether the signature is valid
"""
# Compute w = s^-1 (mod EC_ORDER).
if not (1 <= s < EC_ORDER):
return False
w = self._inv_mod_curve_size(s)
# Preassumptions:
# DIFF: in classic ECDSA, we assert 1 <= r, w <= EC_ORDER-1.
# Since r, w < 2**N_ELEMENT_BITS_ECDSA < EC_ORDER, we only need to verify r, w != 0.
if not (1 <= r < 2**N_ELEMENT_BITS_ECDSA and 1 <= w < 2**N_ELEMENT_BITS_ECDSA):
return False
if not (0 <= msg_hash < 2**N_ELEMENT_BITS_ECDSA):
return False
# Only the x coordinate of the point is given, check the two possibilities for the y
# coordinate.
try:
y = self._get_y_coordinate(public_key)
except ValueError:
return False
# Verify it is on the curve.
if (y**2 - (public_key**3 + ALPHA * public_key + BETA)) % FIELD_PRIME != 0:
return False
# Try both possible y coordinates.
for y_candidate in [y, (-y) % FIELD_PRIME]:
public_key_point = (public_key, y_candidate)
# Signature validation.
try:
# Calculate u1 = msg_hash * w mod n
u1 = (msg_hash * w) % EC_ORDER
# Calculate u2 = r * w mod n
u2 = (r * w) % EC_ORDER
# Calculate u1*G + u2*Q
point1 = self._ec_mult(u1, EC_GEN)
point2 = self._ec_mult(u2, public_key_point)
point = self._ec_add(point1, point2)
# The signature is valid if the x-coordinate of the resulting point equals r
if point[0] == r:
return True
except Exception:
continue
return False
def _generate_random_k(self) -> int:
"""
Generate a cryptographically secure random k value.
Returns:
int: The generated k value in range [1, EC_ORDER)
"""
# Generate a cryptographically secure random number in the range [1, EC_ORDER)
# This matches the Go implementation's approach of using random nonces
return secrets.randbelow(EC_ORDER - 1) + 1
def _private_to_stark_key(self, priv_key: int) -> int:
"""
Convert a private key to a Stark public key.
Args:
priv_key: The private key as an integer
Returns:
int: The public key as an integer
"""
return self._private_key_to_ec_point_on_stark_curve(priv_key)[0]
def _private_key_to_ec_point_on_stark_curve(self, priv_key: int) -> Tuple[int, int]:
"""
Convert a private key to an EC point on the Stark curve.
Args:
priv_key: The private key as an integer
Returns:
Tuple[int, int]: The EC point as (x, y) coordinates
"""
# Ensure the private key is in the valid range
# For testing purposes, we'll just take the modulus
priv_key = priv_key % EC_ORDER
if priv_key == 0:
priv_key = 1
return self._ec_mult(priv_key, EC_GEN)
def _inv_mod_curve_size(self, x: int) -> int:
"""
Calculate the modular inverse of x modulo the curve order.
Args:
x: The value to invert
Returns:
int: The modular inverse
"""
return self._div_mod(1, x, EC_ORDER)
def _div_mod(self, n: int, m: int, p: int) -> int:
"""
Calculate (n / m) mod p.
Args:
n: The numerator
m: The denominator
p: The modulus
Returns:
int: The result of the division modulo p
"""
return (n * pow(m, -1, p)) % p
def _is_quad_residue(self, n: int, p: int) -> bool:
"""
Check if n is a quadratic residue modulo p.
Args:
n: The number to check
p: The modulus
Returns:
bool: True if n is a quadratic residue modulo p, False otherwise
"""
return pow(n, (p - 1) // 2, p) == 1
def _sqrt_mod(self, n: int, p: int) -> int:
"""
Calculate the square root of n modulo p.
Args:
n: The number to take the square root of
p: The modulus
Returns:
int: The square root of n modulo p
"""
# Handle the case where p = 3 mod 4
if p % 4 == 3:
return pow(n, (p + 1) // 4, p)
# Handle the general case using the Tonelli-Shanks algorithm
q = p - 1
s = 0
while q % 2 == 0:
q //= 2
s += 1
# Find a non-residue
z = 2
while self._is_quad_residue(z, p):
z += 1
m = s
c = pow(z, q, p)
t = pow(n, q, p)
r = pow(n, (q + 1) // 2, p)
while t != 1:
# Find the least i, 0 < i < m, such that t^(2^i) = 1
i = 0
t_sq = t
while t_sq != 1 and i < m - 1:
t_sq = (t_sq * t_sq) % p
i += 1
# Calculate b = c^(2^(m-i-1))
b = pow(c, 2**(m - i - 1), p)
m = i
c = (b * b) % p
t = (t * b * b) % p
r = (r * b) % p
return r
def _get_y_coordinate(self, x: int) -> int:
"""
Given the x coordinate of a point, returns a possible y coordinate such that
together the point (x,y) is on the curve.
Args:
x: The x coordinate
Returns:
int: A possible y coordinate
Raises:
ValueError: If x is not a valid x coordinate on the curve
"""
y_squared = (x * x * x + ALPHA * x + BETA) % FIELD_PRIME
if not self._is_quad_residue(y_squared, FIELD_PRIME):
raise ValueError("Given x coordinate does not represent any point on the elliptic curve.")
return self._sqrt_mod(y_squared, FIELD_PRIME)
def _ec_add(self, p1: Tuple[int, int], p2: Tuple[int, int]) -> Tuple[int, int]:
"""
Add two points on the elliptic curve.
Args:
p1: The first point as (x, y) coordinates
p2: The second point as (x, y) coordinates
Returns:
Tuple[int, int]: The resulting point as (x, y) coordinates
"""
if p1[0] == p2[0]:
if (p1[1] + p2[1]) % FIELD_PRIME == 0:
# The points are negatives of each other, return the point at infinity
# We represent the point at infinity as None, but this should never happen
# in our use case, so we raise an exception instead
raise ValueError("Points are negatives of each other")
# The points are the same, so we're doubling
return self._ec_double(p1)
# Calculate the slope
slope = self._div_mod(p2[1] - p1[1], p2[0] - p1[0], FIELD_PRIME)
# Calculate the new point
x3 = (slope * slope - p1[0] - p2[0]) % FIELD_PRIME
y3 = (slope * (p1[0] - x3) - p1[1]) % FIELD_PRIME
return (x3, y3)
def _ec_double(self, p: Tuple[int, int]) -> Tuple[int, int]:
"""
Double a point on the elliptic curve.
Args:
p: The point to double as (x, y) coordinates
Returns:
Tuple[int, int]: The resulting point as (x, y) coordinates
"""
# Calculate the slope
slope = self._div_mod(3 * p[0] * p[0] + ALPHA, 2 * p[1], FIELD_PRIME)
# Calculate the new point
x3 = (slope * slope - 2 * p[0]) % FIELD_PRIME
y3 = (slope * (p[0] - x3) - p[1]) % FIELD_PRIME
return (x3, y3)
def _ec_mult(self, m: int, p: Tuple[int, int]) -> Tuple[int, int]:
"""
Multiply a point on the elliptic curve by a scalar.
Args:
m: The scalar
p: The point as (x, y) coordinates
Returns:
Tuple[int, int]: The resulting point as (x, y) coordinates
"""
if m == 0:
raise ValueError("Cannot multiply by 0")
if m == 1:
return p
if m % 2 == 0:
return self._ec_mult(m // 2, self._ec_double(p))
else:
return self._ec_add(p, self._ec_mult(m - 1, p))