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// Copyright 2020 The Tink-Rust Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////////

//! Provides subtle implementations of the Streaming AEAD primitive.

mod aes_ctr_hmac;
pub use aes_ctr_hmac::*;
mod aes_gcm_hkdf;
pub use aes_gcm_hkdf::*;

pub mod noncebased;

/// Supported AES variants.
#[derive(Clone, Copy)]
pub enum AesVariant {
    Aes128,
    Aes256,
}

/// Check if the given key size is a valid AES key size.
pub fn validate_aes_key_size(size_in_bytes: usize) -> Result<AesVariant, tink_core::TinkError> {
    match size_in_bytes {
        16 => Ok(AesVariant::Aes128),
        32 => Ok(AesVariant::Aes256),
        _ => Err(format!("invalid AES key size; want 16 or 32, got {}", size_in_bytes).into()),
    }
}

impl AesVariant {
    /// Return the key size in bytes for the specified AES variant.
    pub fn key_size(&self) -> usize {
        match self {
            AesVariant::Aes128 => 16,
            AesVariant::Aes256 => 32,
        }
    }
}