# K230 SHA256 API reference

## Function introduction

SHA256 is mainly used to calculate the hash value of data. The SHA256 algorithm is implemented in the large core rt-smart and is used to calculate the hash value of data. The code logic is shown in the figure below:

![sha256](https://kendryte-download.canaan-creative.com/developer/pictures/sha256.png)

## API Reference

The SHA256 module mainly provides the following APIs:

- [kd_mpi_cipher_sha256](#kd_mpi_cipher_sha256)

### kd_mpi_cipher_sha256

Description

Calculate the hash value of the message based on the incoming message.

Syntax

kd_mpi_cipher_sha256(const void \*data, k_u32 len, k_u8 \*hash);

Parameters

| Parameter Name | Description | Input/Output |
|-----------------|-------------------------------|-----------|
| data | incoming message | Input |
| len | The length of the incoming message | Input |
| hash | The calculated hash value | Output |

Return Value

| Return Value | Description |
|---------|---------------------------------|
| 0 | success. |
| Not 0 | Failure, refer to error code definition |

Chip differences

None

Requirements

- Header File: mpi_cipher_api.h
- Library File: libcipher.a

Notes

None

Example

None

Related Topics

None

## Debugging and printing information

Write a userland application *sample_hash.c* to test the SHA256 functionality.

The test code has been written and is located in the *src/rtsmart/examples/mpp/sample_cipher/sample_hash* directory. The specific debugging method is as follows:

1. After the big core is started, enter the *bin* directory;
1. Run the *sample_hash.elf* program;
1. Print information.

The specific printing information is as follows:

```shell
msh />cd bin/
msh /bin>./sample_hash.elf
input = ''
digest: e3b0c442 98fc1c14 9afbf4c8 996fb924 27ae41e4 649b934c a495991b 7852b855
result: PASS

input = 'abc'
digest: ba7816bf 8f01cfea 414140de 5dae2223 b00361a3 96177a9c b410ff61 f20015ad
result: PASS

input = 'abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq'
digest: 248d6a61 d20638b8 e5c02693 0c3e6039 a33ce459 64ff2167 f6ecedd4 19db06c1
result: PASS

input = 'The quick brown fox jumps over the lazy dog'
digest: d7a8fbb3 07d78094 69ca9abc b0082e4f 8d5651e4 6d3cdb76 2d02d0bf 37c9e592
result: PASS

input = 'The quick brown fox jumps over the lazy cog'
digest: e4c4d8f3 bf76b692 de791a17 3e053211 50f7a345 b46484fe 427f6acc 7ecc81be
result: PASS

input = 'bhn5bjmoniertqea40wro2upyflkydsibsk8ylkmgbvwi420t44cq034eou1szc1k0mk46oeb7ktzmlxqkbte2sy'
digest: 9085df2f 02e0cc45 5928d0f5 1b27b4bf 1d9cd260 a66ed1fd a11b0a3f f5756d99
result: PASS
```