SM2 is a public-key cryptographic algorithm based on elliptic curves, published by the Chinese State Cryptography Administration (SCA) in 2010. It's part of the Chinese national cryptographic standard (GM/T 0003) and is mandatory for certain government and financial applications in China. SM2 provides 128-bit security level, comparable to RSA-3072 or NIST P-256.

What's the difference between C1C3C2 and C1C2C3 modes?

These are two different ciphertext formats defined in the SM2 standard. C1C3C2 (mode 1) is the default and recommended format: C1 (elliptic curve point) + C3 (hash value) + C2 (encrypted data). C1C2C3 (mode 0) is an alternative format. Both provide the same security level. Use C1C3C2 unless you have specific compatibility requirements.

How does SM2 compare to RSA and ECDSA?

SM2 is based on a 256-bit elliptic curve, providing 128-bit security. This is equivalent to RSA-3072 or NIST P-256 (ECDSA). SM2 is generally faster than RSA for the same security level. Compared to ECDSA, SM2 uses a different curve equation and hash function (SM3), making it independent of NIST standards.

SM2 has been extensively analyzed by cryptographers worldwide. The curve parameters were chosen to resist known attacks, and no weaknesses have been found. SM2 is approved by the International Organization for Standardization (ISO) as ISO/IEC 14888-3 and is considered cryptographically strong. It's widely used in Chinese government, banking, and critical infrastructure.

Can I use SM2 for commercial applications?

Yes, SM2 is free to use without licensing fees. The algorithm specifications are publicly available (GM/T 0003). For applications in China's financial or government sectors, SM2 may be mandatory under Chinese regulations. For international applications, consider compatibility requirements with existing systems.

Tools

Mode

SM2 Encryption — Chinese National Standard Asymmetric Encryption

Free SM2 encryption tool for key generation, encryption, decryption, and digital signatures. SM2 is the Chinese national standard for elliptic curve cryptography (GM/T 0003). Supports C1C3C2 and C1C2C3 cipher modes. All operations performed locally in your browser.

Features

✓Generate SM2 key pairs (256-bit elliptic curve)
✓Encrypt data with public key
✓Decrypt ciphertext with private key
✓Sign messages with private key
✓Verify signatures with public key
✓Support C1C3C2 and C1C2C3 cipher modes
✓Compressed public key support (66 chars)
✓SM3 hash integration for signatures
✓Chinese national standard GM/T 0003
✓All operations performed locally in browser

How to Use

1Key Generation: Click 'Generate Key Pair' to create a new SM2 key pair.
2Encryption: Enter plaintext and public key, then click 'Encrypt'.
3Decryption: Enter ciphertext and private key, then click 'Decrypt'.
4Signing: Enter message and private key, then click 'Sign'.
5Verification: Enter message, signature, and public key, then click 'Verify'.

Frequently Asked Questions

Related Tools

SM4 Encryption — Chinese National Standard Symmetric Encryption

Free SM4 encryption tool for key generation, encryption, and decryption. SM4 is the Chinese national standard for symmetric block cipher (GM/T 0002). Supports ECB and CBC modes. All operations performed locally in your browser.