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Testing Curve25519 Scalar Base Multiplication in Telegram

This test suite validates the Curve25519 elliptic curve cryptography implementation, specifically focusing on scalar base multiplication operations. The tests ensure correct mathematical computations and cryptographic properties of the curve operations.

Test Coverage Overview

The test suite provides comprehensive coverage of the Curve25519 scalar base multiplication functionality.

Key areas tested include:

Iterative scalar base multiplication operations
Verification against known expected output values
Multiple rounds of computation to ensure consistency
Edge case handling with specific byte array inputs

Implementation Analysis

The testing approach uses Go’s native testing framework to validate cryptographic operations. The implementation employs a systematic verification pattern, performing 200 iterations of scalar base multiplication and comparing against a known expected result hex value.

Technical patterns include:

Byte array manipulation for cryptographic inputs
In-place memory optimization with pointer swapping
Hex string comparison for verification

Technical Details

Testing tools and configuration:

Go testing framework (testing package)
fmt package for hex string formatting
32-byte array structures for cryptographic values
Constant expected hex value for verification
ScalarBaseMult function from curve25519 package

Best Practices Demonstrated

The test implementation showcases several testing best practices in cryptographic verification.

Notable practices include:

Deterministic test cases with known expected values
Memory-efficient implementation with buffer reuse
Clear error messaging with actual vs expected values
Focused test scope for specific cryptographic operation
Proper separation of test data and logic

drklo/telegram

TMessagesProj/jni/boringssl/ssl/test/runner/curve25519/curve25519_test.go

            
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package curve25519

import (
	"fmt"
	"testing"
)

const expectedHex = "89161fde887b2b53de549af483940106ecc114d6982daa98256de23bdf77661a"

func TestBaseScalarMult(t *testing.T) {
	var a, b [32]byte
	in := &a
	out := &b
	a[0] = 1

	for i := 0; i < 200; i++ {
		ScalarBaseMult(out, in)
		in, out = out, in
	}

	result := fmt.Sprintf("%x", in[:])
	if result != expectedHex {
		t.Errorf("incorrect result: got %s, want %s", result, expectedHex)
	}
}