SM4 Block Cipher Algorithm

Chinese commercial cryptography standard SM4 algorithm, 128-bit block symmetric encryption, supporting CBC/ECB/CTR modes with automatic key and IV generation

SM4 Block Cipher

Encryption Mode

Generate Key

Generate IV

Encrypt

Key

Initialization Vector

Plaintext

Input Format

Output Format

Decrypt

Key

Initialization Vector

Ciphertext

Input Format

Output Format

Documentation

This tool performs SM4 encryption and decryption with local browser-side processing, supporting multiple modes and format conversions.

Key Features

Modes: ECB, CBC, and CTR
Generate random key and IV
Input/output formats: Text/Base64/Hex/Spaced Hex/C-style Hex
One-click copy for encryption/decryption result

Steps

Select mode and prepare key (IV required for CBC/CTR).
Choose input/output formats.
Enter plaintext or ciphertext and run encryption/decryption.
Copy output for integration.

Use Cases

SM4 interoperability and integration testing
Local client-side encryption demos
Learning and validating national symmetric crypto flows

Notes

ECB does not use IV, while CBC/CTR requires correct IV.
Both sides must use identical mode, key, and IV.
In production, combine with secure key distribution and storage.