EVP_SM4_CBC(3)

💖 EVP_SM4_CBC(3) 💖

Okay bestie, settle in: this is the EVP_SM4_CBC(3) page from the Library Functions Manual, and it's all about the SM4 cipher squad. It's giving "block cipher family, but make it EVP." Let's get into it. 💅

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✨ NAME ✨

The whole function fam is here:

• EVP_sm4_cbc
• EVP_sm4_ecb
• EVP_sm4_cfb
• EVP_sm4_cfb128
• EVP_sm4_ofb
• EVP_sm4_ctr

Collectively: the EVP SM4 cipher. periodt.

🌸 SYNOPSIS 🌸

The library line is literally:

library “libcrypto” #include <openssl/evp.h>

Then the declared besties all return const EVP_CIPHER * and look like this:

const EVP_CIPHER *
EVP_sm4_cbc(void);

const EVP_CIPHER *
EVP_sm4_ecb(void);

const EVP_CIPHER *
EVP_sm4_cfb(void);

const EVP_CIPHER *
EVP_sm4_cfb128(void);

const EVP_CIPHER *
EVP_sm4_ofb(void);

const EVP_CIPHER *
EVP_sm4_ctr(void);

💖 DESCRIPTION 💖

These functions provide the SM4 blockcipher in the evp(3) framework. That's the whole assignment. 💖

All modes use a key length of 128 bits and act on blocks of 128 bits. No cap.

EVP_sm4_cfb() is an alias for EVP_sm4_cfb128(), implemented as a macro. So yes, same energy, macro-style. 🫶

With an argument of "sm4" or "SM4", EVP_get_cipherbyname(3) returns EVP_sm4_cbc(). Iykyk.

🎀 RETURN VALUES 🎀

These functions return an EVP_CIPHER structure that provides the implementation of the symmetric cipher. That's the return-value tea. 🍓

🦋 SEE ALSO 🦋

• evp(3)
• EVP_EncryptInit(3)

Go read those if you wanna keep the cipher lore going, bestie. 💜

🌈 STANDARDS 🌈

The standard citation is:

Information security technology - SM4 block cipher algorithm, National Standards of People's Republic of China, GB/T 32907-2016, August 29, 2016.

⭐ HISTORY ⭐

These functions appeared in OpenSSL 1.1.1 and have been available since OpenBSD 6.5. Iconic timeline behavior. ✨

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Catch you later — this page's footer is from Debian, dated June 8, 2025, page name EVP_SM4_CBC(3). Mwah. 💋