docs/sql-manual/sql-functions/encrypt-digest-functions/sm4-encrypt.md

---
{
"title": "SM4_ENCRYPT",
"language": "en"
}
---

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### Description

SM4 is a China's national standard symmetric key encryption algorithm, widely used in finance, communications, e-commerce, and other fields. The SM4_ENCRYPT function is used to encrypt data using the SM4 algorithm. By default, it uses the `SM4_128_ECB` algorithm.

### Syntax

```sql
VARCHAR SM4_ENCRYPT(VARCHAR str, VARCHAR key_str[, VARCHAR init_vector][, VARCHAR encryption_mode])
```

### Parameters

- `str` is the text to be encrypted;
- `key_str` is the key. Note that this key is not a hexadecimal encoding, but a string representation of the encoded key. For example, for 128-bit key encryption, `key_str` should be 16-length. If the key is not long enough, use **zero padding** to make it up. If it is longer than that, the final key is found using a cyclic xor method. For example, if the 128-bit key used by the algorithm finally is `key`, then `key[i] = key_str[i] ^ key_str[i+128] ^ key_str[i+256] ^ ...`
- `init_vector` is the initial vector to be used in the algorithm, this is only valid for some algorithms, if not specified then Doris will use the built-in value;
- `encryption_mode` is the encryption algorithm, optionally available in variable.

### Example

```sql
set block_encryption_mode='';
select TO_BASE64(SM4_ENCRYPT('text','F3229A0B371ED2D9441B830D21A390C3'));
```

```
+----------------------------------------------------------+
| to_base64(sm4_encrypt('text', '***', '', 'SM4_128_ECB')) |
+----------------------------------------------------------+
| aDjwRflBrDjhBZIOFNw3Tg==                                 |
+----------------------------------------------------------+
```

```sql
set block_encryption_mode="SM4_128_CBC";
select TO_BASE64(SM4_ENCRYPT('text','F3229A0B371ED2D9441B830D21A390C3')); --- since 2.1.7
```

```
+----------------------------------------------------------+
| to_base64(sm4_encrypt('text', '***', '', 'SM4_128_CBC')) |
+----------------------------------------------------------+
| FSYstvOmH2cXy7B/072Mug==                                 |
+----------------------------------------------------------+
```

```sql
select to_base64(SM4_ENCRYPT('text','F3229A0B371ED2D9441B830D21A390C3', '0123456789'));
```
+----------------------------------------------------------------------------------+
| to_base64(sm4_encrypt('text', 'F3229A0B371ED2D9441B830D21A390C3', '0123456789')) |
+----------------------------------------------------------------------------------+
| G7yqOKfEyxdagboz6Qf01A==                                                         |
+----------------------------------------------------------------------------------+
```