# botan

A wrapper for the Botan cryptography library

## Supported
This library offers full bindings for everything exposed by Botan's FFI.
Wrappers for hashing algorithms have been added to match the API within
the Odin `core:crypto` library.

## Hashing algorithms

| Algorithm                                                                                                    |                  |
|:-------------------------------------------------------------------------------------------------------------|:-----------------|
| [BLAKE2B](https://datatracker.ietf.org/doc/html/rfc7693)                                                     | ✔️ |
| [SHA-2](https://csrc.nist.gov/csrc/media/publications/fips/180/2/archive/2002-08-01/documents/fips180-2.pdf) | ✔️ |
| [SHA-3](https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf)                                            | ✔️ |
| [SHAKE](https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf)                                            | ✔️ |
| [SM3](https://datatracker.ietf.org/doc/html/draft-sca-cfrg-sm3-02)                                           | ✔️ |
| legacy/[Keccak](https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf)                                    | ✔️ |
| legacy/[MD5](https://datatracker.ietf.org/doc/html/rfc1321)                                                  | ✔️ |
| legacy/[SHA-1](https://datatracker.ietf.org/doc/html/rfc3174)                                                | ✔️ |

#### High level API

Each hash algorithm contains a procedure group named `hash`, or if the algorithm provides more than one digest size `hash_<size>`.
Included in these groups are six procedures.
- `hash_string` - Hash a given string and return the computed hash. Just calls `hash_bytes` internally
- `hash_bytes` - Hash a given byte slice and return the computed hash
- `hash_string_to_buffer` - Hash a given string and put the computed hash in the second proc parameter. Just calls `hash_bytes_to_buffer` internally
- `hash_bytes_to_buffer` - Hash a given string and put the computed hash in the second proc parameter. The destination buffer has to be at least as big as the digest size of the hash
- `hash_stream` - Takes a stream from io.Stream and returns the computed hash from it
- `hash_file` - Takes a file handle and returns the computed hash from it. A second optional boolean parameter controls if the file is streamed (this is the default) or read at once (set to true)

#### Low level API

The above mentioned procedures internally call three procedures: `init`, `update` and `final`.
You may also directly call them, if you wish.

#### Example
```odin
package crypto_example

// Import the desired package
import "vendor:botan/blake2b"

main :: proc() {
    input := "foo"

    // Compute the hash, using the high level API
    computed_hash := blake2b.hash(input)

    // Variant that takes a destination buffer, instead of returning the computed hash
    hash := make([]byte, blake2b.DIGEST_SIZE) // @note: Destination buffer has to be at least as big as the digest size of the hash
    blake2b.hash(input, hash[:])

    // Compute the hash, using the low level API
    // @note: Botan's structs are opaque by design, they don't expose any fields
    ctx: blake2b.Context
    computed_hash_low: [blake2b.DIGEST_SIZE]byte
    blake2b.init(&ctx)
    blake2b.update(&ctx, transmute([]byte)input)
    blake2b.final(&ctx, computed_hash_low[:])
}
```
For example uses of all available algorithms, please see the tests within `tests/vendor/botan`.

### License

This library is made available under the BSD-3 license.