EVP_CIPHER-SM4(7)

NAME
EVP_CIPHER-SM4 - The SM4 EVP_CIPHER implementations

DESCRIPTION
Support for SM4 symmetric encryption using the EVP_CIPHER API.

  Algorithm Names
The following algorithms are available in the default provider:

"SM4-CBC:SM4"
"SM4-ECB"
"SM4-CTR"
"SM4-OFB" or "SM4-OFB128"
"SM4-CFB" or "SM4-CFB128"
"SM4-GCM"
"SM4-CCM"
"SM4-XTS"

  Parameters
This implementation supports the parameters described in "PARAMETERS" in EVP_EncryptInit(3).

NOTES
SM4 implementations in OpenSSL may use secret-dependent table lookups and are not guaranteed to be constant-time. In particular, the portable C implementation uses S-box and T-table lookups and may be vulnerable to cache-timing side-channel attacks. Which code path is used depends on CPU capabilities; see OPENSSL_armcap(3), OPENSSL_ia32cap(3) and OPENSSL_riscvcap(3).

The SM4-XTS implementation allows streaming to be performed, but each EVP_EncryptUpdate(3) or EVP_DecryptUpdate(3) call requires each input to be a multiple of the blocksize. Only the final EVP_EncryptUpdate() or EVP_DecryptUpdate() call can optionally have an input that is not a multiple of the blocksize but is larger than one block. In that case ciphertext stealing (CTS) is used to fill the block.

SEE ALSO
OPENSSL_armcap(3), OPENSSL_ia32cap(3), OPENSSL_riscvcap(3), OSSL_PROVIDER-default(7), provider-cipher(7)

COPYRIGHT
Copyright 2021-2026 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.