Understanding AES Modes 的操作

问题

你需要选择 AES 模式但 是 unsure 如何 ECB, CBC, CTR, 和 GCM 不同在 安全与性能.

前置条件

• Understanding 的 AES 阻止 cipher
• Knowledge 的 IVs 和 padding

步骤

1. 1. Review the mode characteristics

   ECB encrypts each block independently and leaks patterns. CBC chains blocks with an IV and requires padding. CTR turns AES into a stream cipher and needs no padding. GCM adds authentication on top of CTR. Each mode has different security properties and performance trade-offs.

   输入

   modes: ECB, CBC, CTR, GCM

   输出

   GCM recommended for most uses

2. 2. Evaluate authentication needs

   If you need to detect tampering, use an authenticated mode like GCM or ChaCha20-Poly1305. CBC and CTR provide confidentiality only; an attacker can modify the ciphertext undetected. Adding an HMAC over the ciphertext is an alternative for non-GCM modes.

   输入

   need integrity?

   输出

   use GCM or Encrypt-then-MAC

3. 3. Choose based on constraints

   For most modern applications, GCM is the default choice: it provides authenticated encryption and is hardware-accelerated. Use CTR for streaming contexts where authentication is handled separately. Never use ECB for more than a single block.

   输入

   general purpose

   输出

   AES-256-GCM

预期结果

informed choice 的 AES 模式该 provides needed 安全 properties 为你的用例.

常见错误

Using ECB for multi-block data

ECB leaks patterns. The famous ECB penguin image demonstrates how identical plaintext blocks produce identical ciphertext blocks. Use CBC or GCM instead.

Using CBC without authenticating the ciphertext

CBC is malleable. Apply an HMAC over the IV and ciphertext (encrypt-then-MAC) or switch to GCM.

排障指引

• If performance is critical, GCM is hardware-accelerated on modern CPUs via AES-NI.
• If you need a stream cipher without padding, CTR mode is the right choice.

安全限制

• Always prefer authenticated encryption (GCM). Non-authenticated modes allow ciphertext manipulation.