如何Use ChaCha20 Encryption
加密 data with the ChaCha20 stream cipher, preferably with Poly1305 authentication.
问题
你 need 快, 安全流式处理 cipher 该不 require hardware AES acceleration, 如开 mobile 或 IoT devices.
前置条件
- Understanding 的流式处理 ciphers
- Knowledge 的已认证加密
步骤
-
1. Generate a key and nonce
ChaCha20 uses a 256-bit key and a 96-bit nonce (when used with Poly1305). Generate both using a CSPRNG. The nonce must be unique per key, just like in GCM.
输入256-bit key + 96-bit nonce输出32 + 12 random bytes -
2. Encrypt with ChaCha20-Poly1305
Use the authenticated ChaCha20-Poly1305 construction rather than raw ChaCha20. Poly1305 provides integrity, preventing ciphertext tampering. The cipher produces ciphertext and a 128-bit authentication tag.
输入plaintext + key + nonce输出ciphertext + tag -
3. Verify the tag on decryption
On decryption, verify the Poly1305 tag before using the plaintext. If the tag does not match, reject the data. This prevents using tampered or corrupted ciphertext.
输入ciphertext + tag + key输出plaintext (if tag valid)
预期结果
快已认证加密 suitable 为 environments 无 AES hardware acceleration.
常见错误
- Using raw ChaCha20 without Poly1305
- Raw ChaCha20 provides no integrity. Always use ChaCha20-Poly1305 for authenticated encryption.
- Reusing the nonce
- Like GCM, nonce reuse in ChaCha20-Poly1305 is catastrophic. Generate a unique nonce per encryption.
排障指引
- If performance is the concern, ChaCha20-Poly1305 is often faster than AES-GCM on devices without AES-NI.
- ChaCha20-Poly1305 is used in TLS 1.3 and WireGuard, proving its real-world adoption.
安全限制
- ChaCha20-Poly1305 is a modern, well-analyzed cipher. Its main risk is nonce reuse, which must be prevented.
- All operations are local.