summaryrefslogtreecommitdiff
path: root/src/kms/awskms.rs
blob: 9a9a0613ed230e4772cfa65c853cc71f0ebe9c84 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
// 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 {
    extern crate bytes;

    use std::collections::HashMap;
    use std::default::Default;
    use std::fmt;
    use std::fmt::Formatter;
    use std::str::FromStr;

    use rusoto_core::Region;
    use rusoto_kms::{DecryptRequest, EncryptRequest, Kms, KmsClient};
    use bytes::Bytes;

    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.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 = Bytes::from(plaintext_dek.as_slice());

            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.to_vec())
                    } else {
                        Err(KmsError::OperationFailed(
                            "no ciphertext despite successful response".to_string(),
                        ))
                    }
                }
                Err(e) => Err(KmsError::OperationFailed(e.to_string())),
            }
        }

        fn decrypt_dek(&self, encrypted_dek: &EncryptedDEK) -> Result<PlaintextDEK, KmsError> {
            let mut decrypt_req: DecryptRequest = Default::default();
            decrypt_req.ciphertext_blob = Bytes::from(encrypted_dek.as_slice());

            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.to_vec())
                        } 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.to_string())),
            }
        }
    }

    #[cfg(feature = "awskms")]
    impl fmt::Display for AwsKms {
        fn fmt(&self, f: &mut Formatter) -> fmt::Result {
            write!(f, "{}", self.key_id)
        }
    }
}