test: add unit tests for crypto_utils (Issue hiero-ledger#993)

Signed-off-by: adityashirsatrao007 <adityashirsatrao007@gmail.com>

Author: adityashirsatrao007

CHANGELOG.md

@@ -7,9 +7,11 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 ## [Unreleased]
 
 ### Added
+
 - Modularized `transfer_transaction_fungible` example by introducing `account_balance_query()` & `transfer_transaction()`.Renamed `transfer_tokens()` → `main()`
 - Phase 2 of the inactivity-unassign bot:Automatically detects stale open pull requests (no commit activity for 21+ days), comments with a helpful InactivityBot message, closes the stale PR, and unassigns the contributor from the linked issue.
 - Added **str**() to CustomFixedFee and updated examples and tests accordingly.
+- Added unit tests for `crypto_utils` (#993)
 - Added a github template for good first issues
 - Added `.github/workflows/bot-assignment-check.yml` to limit non-maintainers to 2 concurrent issue assignments.
 - Added all missing fields to **str**() method and updated `test_tokem_info.py`
@@ -19,7 +21,7 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 - Made custom fraction fee end to end
 - feat: AccountCreateTransaction now supports both PrivateKey and PublicKey [#939](https://github.com/hiero-ledger/hiero-sdk-python/issues/939)
 - Added Acceptance Criteria section to Good First Issue template for better contributor guidance (#997)
-- Added __str__() to CustomRoyaltyFee and updated examples and tests accordingly (#986)
+- Added **str**() to CustomRoyaltyFee and updated examples and tests accordingly (#986)
 - Restore bug and feature request issue templates (#996)(https://github.com/hiero-ledger/hiero-sdk-python/issues/996)
 - Support selecting specific node account ID(s) for queries and transactions and added `Network._get_node()` with updated execution flow (#362)
 - Add TLS support with two-stage control (`set_transport_security()` and `set_verify_certificates()`) for encrypted connections to Hedera networks. TLS is enabled by default for hosted networks (mainnet, testnet, previewnet) and disabled for local networks (solo, localhost) (#855)

tests/unit/crypto_utils_test.py

@@ -0,0 +1,72 @@
+"""Unit tests for crypto_utils module."""
+from cryptography.hazmat.primitives.asymmetric import ec
+
+from hiero_sdk_python.utils.crypto_utils import (
+    compress_point_unchecked,
+    compress_with_cryptography,
+    decompress_point,
+    keccak256,
+)
+
+
+def test_keccak256():
+    """Test keccak256 hashing."""
+    # Known vector: empty string -> c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470
+    assert keccak256(b"").hex() == "c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470"
+
+    # "hello" -> 1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8
+    assert keccak256(b"hello").hex() == "1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8"
+
+
+def test_compress_point_unchecked():
+    """Test point compression logic."""
+    # Use cryptography to generate a valid point
+    priv = ec.generate_private_key(ec.SECP256K1())
+    pub = priv.public_key()
+    nums = pub.public_numbers()
+    x = nums.x
+    y = nums.y
+
+    compressed = compress_point_unchecked(x, y)
+    assert len(compressed) == 33
+
+    # Verify expected prefix
+    expected_prefix = 0x03 if y % 2 else 0x02
+    assert compressed[0] == expected_prefix
+    assert int.from_bytes(compressed[1:], "big") == x
+
+
+def test_decompress_point():
+    """Test point decompression logic."""
+    priv = ec.generate_private_key(ec.SECP256K1())
+    pub = priv.public_key()
+    nums = pub.public_numbers()
+
+    # Create valid compressed point
+    compressed = compress_point_unchecked(nums.x, nums.y)
+
+    # Test decompression
+    x, y = decompress_point(compressed)
+    assert x == nums.x
+    assert y == nums.y
+
+    # Test uncompressed 65-byte format (0x04 + x + y)
+    uncompressed = b'\x04' + nums.x.to_bytes(32, 'big') + nums.y.to_bytes(32, 'big')
+    x2, y2 = decompress_point(uncompressed)
+    assert x2 == nums.x
+    assert y2 == nums.y
+
+
+def test_compress_with_cryptography():
+    """Test compression using cryptography library."""
+    priv = ec.generate_private_key(ec.SECP256K1())
+    pub = priv.public_key()
+    nums = pub.public_numbers()
+
+    # Create uncompressed
+    uncompressed = b'\x04' + nums.x.to_bytes(32, 'big') + nums.y.to_bytes(32, 'big')
+
+    compressed_via_lib = compress_with_cryptography(uncompressed)
+    compressed_manual = compress_point_unchecked(nums.x, nums.y)
+
+    assert compressed_via_lib == compressed_manual