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// Copyright 2017-2019 int08h LLC
//
// 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.
#[cfg(feature = "awskms")]
pub mod inner {
use std::collections::HashMap;
use std::default::Default;
use std::error::Error;
use std::fmt;
use std::fmt::Formatter;
use std::str::FromStr;
use rusoto_core::Region;
use rusoto_kms::{DecryptRequest, EncryptRequest, Kms, KmsClient};
use crate::kms::{EncryptedDEK, KmsError, KmsProvider, PlaintextDEK, AD, DEK_SIZE_BYTES};
/// Amazon Web Services Key Management Service
/// https://aws.amazon.com/kms/
pub struct AwsKms {
kms_client: KmsClient,
key_id: String,
}
impl AwsKms {
/// Create a new instance from the full ARN of a AWS KMS key. The ARN is expected
/// to be of the form `arn:aws:kms:some-aws-region:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab`
pub fn from_arn(arn: &str) -> Result<Self, KmsError> {
let parts: Vec<&str> = arn.split(':').collect();
if parts.len() != 6 {
return Err(KmsError::InvalidConfiguration(format!(
"invalid KMS arn: too few parts {}",
parts.len()
)));
}
let region_part = parts.get(3).expect("region is missing");
let region = match Region::from_str(region_part) {
Ok(r) => r,
Err(e) => return Err(KmsError::InvalidConfiguration(e.description().to_string())),
};
Ok(AwsKms {
kms_client: KmsClient::new(region),
key_id: arn.to_string(),
})
}
}
impl KmsProvider for AwsKms {
fn encrypt_dek(&self, plaintext_dek: &PlaintextDEK) -> Result<EncryptedDEK, KmsError> {
if plaintext_dek.len() != DEK_SIZE_BYTES {
return Err(KmsError::InvalidKey(format!(
"provided DEK wrong length: {}",
plaintext_dek.len()
)));
}
let mut encrypt_req: EncryptRequest = Default::default();
encrypt_req.key_id = self.key_id.clone();
encrypt_req.plaintext = plaintext_dek.clone();
let mut enc_context = HashMap::new();
enc_context.insert("AD".to_string(), AD.to_string());
encrypt_req.encryption_context = Some(enc_context);
match self.kms_client.encrypt(encrypt_req).sync() {
Ok(result) => {
if let Some(ciphertext) = result.ciphertext_blob {
Ok(ciphertext)
} else {
Err(KmsError::OperationFailed(
"no ciphertext despite successful response".to_string(),
))
}
}
Err(e) => Err(KmsError::OperationFailed(e.description().to_string())),
}
}
fn decrypt_dek(&self, encrypted_dek: &EncryptedDEK) -> Result<PlaintextDEK, KmsError> {
let mut decrypt_req: DecryptRequest = Default::default();
decrypt_req.ciphertext_blob = encrypted_dek.clone();
let mut dec_context = HashMap::new();
dec_context.insert("AD".to_string(), AD.to_string());
decrypt_req.encryption_context = Some(dec_context);
match self.kms_client.decrypt(decrypt_req).sync() {
Ok(result) => {
if let Some(plaintext_dek) = result.plaintext {
if plaintext_dek.len() == DEK_SIZE_BYTES {
Ok(plaintext_dek)
} else {
Err(KmsError::InvalidKey(format!(
"decrypted DEK wrong length: {}",
plaintext_dek.len()
)))
}
} else {
Err(KmsError::OperationFailed(
"decrypted payload is empty".to_string(),
))
}
}
Err(e) => Err(KmsError::OperationFailed(e.description().to_string())),
}
}
}
#[cfg(feature = "awskms")]
impl fmt::Display for AwsKms {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{}", self.key_id)
}
}
}
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