> ## Documentation Index
> Fetch the complete documentation index at: https://docs.projectreal.gg/llms.txt
> Use this file to discover all available pages before exploring further.

# crypt.encrypt

> Encrypts Lua string bytes with AES CBC, ECB, or CTR using a Base64-decoded key, then returns Base64 ciphertext and the IV result.

Encrypts Lua string bytes with AES CBC, ECB, or CTR using a Base64-decoded key, then returns Base64 ciphertext and the IV result.

## Syntax

```lua theme={null}
crypt.encrypt(data: string, key: string, iv?: string, mode?: "CBC" | "ECB" | "CTR" | "AES-CBC" | "AES-ECB" | "AES-CTR"): string | string | nil
```

## Arguments

| Name   | Type                                                             | Required | Description                                                                                                                                   |
| ------ | ---------------------------------------------------------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------- |
| `data` | `string`                                                         | Yes      | Plaintext bytes read from a Lua string.                                                                                                       |
| `key`  | `string`                                                         | Yes      | Base64 key decoded before it is passed to AES.                                                                                                |
| `iv`   | `string`                                                         | No       | Optional Base64 IV for CBC or CTR. When omitted for CBC or CTR, a new AES block-size IV is generated.                                         |
| `mode` | `"CBC" \| "ECB" \| "CTR" \| "AES-CBC" \| "AES-ECB" \| "AES-CTR"` | No       | AES mode. The AES- prefix is removed when present. Defaults to AES-CBC. CBC and ECB use crypto library DEFAULT\_PADDING; CTR uses no padding. |

## Returns

| Name                   | Type            | Description                                     |
| ---------------------- | --------------- | ----------------------------------------------- |
| `ciphertext`           | `string`        | Base64-encoded ciphertext.                      |
| `initializationVector` | `string \| nil` | Base64-encoded IV for CBC and CTR; nil for ECB. |

## Example

Encrypt a Lua string and decrypt the returned ciphertext with the returned IV.

```lua theme={null}
local key = crypt.generatekey()
local ciphertext, iv = crypt.encrypt("hello world", key)

local plaintext = crypt.decrypt(ciphertext, key, iv)

print(ciphertext)
print(iv)
print(plaintext)
```