dat 4.0.2

DAT - Distributed Access Token
Documentation 
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
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158

use crate::crypto::DatCryptoAlgorithm::{IvAes128Gcm, IvAes256Gcm};
use crate::error::DatError;
use aes_gcm::aead::array::Array;
use aes_gcm::aead::common::Generate;
use aes_gcm::aead::consts::{U12, U16, U32};
use aes_gcm::aead::inout::InOutBuf;
use aes_gcm::{AeadInOut, AesGcm, Key, KeyInit, Nonce};
use std::fmt::Display;
use std::str::FromStr;

#[repr(u8)]
#[derive(Debug, Clone, Copy, Eq, PartialEq)]
pub enum DatCryptoAlgorithm {
    IvAes128Gcm,
    IvAes256Gcm,
}

impl DatCryptoAlgorithm {
    #[inline]
    pub fn list() -> &'static [DatCryptoAlgorithm] {
        &[IvAes128Gcm, IvAes256Gcm]
    }
    #[inline]
    pub fn as_str(&self) -> &'static str {
        match self {
            IvAes128Gcm => "IV-AES128-GCM",
            IvAes256Gcm => "IV-AES256-GCM",
        }
    }
}

const IV_LEN: usize = 12;
const TAG_LEN: usize = 16;

impl FromStr for DatCryptoAlgorithm {
    type Err = DatError;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "IV-AES128-GCM" => Ok(IvAes128Gcm),
            "IV-AES256-GCM" => Ok(IvAes256Gcm),
            _ => Err(DatError::UnknownCryptoAlgorithm),
        }
    }
}

impl Display for DatCryptoAlgorithm {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_str())
    }
}

#[derive(Clone)]
pub enum DatCrypto {
    IvAes128Gcm(AesGcm<aes_gcm::aes::Aes128, U12>, Array<u8, U16>),
    IvAes256Gcm(AesGcm<aes_gcm::aes::Aes256, U12>, Array<u8, U32>),
}

impl DatCrypto {
    pub fn generate(algorithm: DatCryptoAlgorithm) -> Self {
        match algorithm {
            IvAes128Gcm => {
                let key = Key::<aes_gcm::aes::Aes128>::generate();
                let cipher = AesGcm::<aes_gcm::aes::Aes128, U12>::new(&key);
                Self::IvAes128Gcm(cipher, key)
            }
            IvAes256Gcm => {
                let key = Key::<aes_gcm::aes::Aes256>::generate();
                let cipher = AesGcm::<aes_gcm::aes::Aes256, U12>::new(&key);
                Self::IvAes256Gcm(cipher, key)
            }
        }
    }

    pub fn from_key(algorithm: DatCryptoAlgorithm, key: &[u8]) -> Result<Self, DatError> {
        match algorithm {
            IvAes128Gcm => {
                let key = Key::<aes_gcm::aes::Aes128>::try_from(key)
            .map_err(|_| DatError::InvalidCryptoKey)?;
                let cipher = AesGcm::<aes_gcm::aes::Aes128, U12>::new(&key);

                Ok(Self::IvAes128Gcm(cipher, key))
            }
            IvAes256Gcm => {
                let key = Key::<aes_gcm::aes::Aes256>::try_from(key)
            .map_err(|_| DatError::InvalidCryptoKey)?;
                let cipher = AesGcm::<aes_gcm::aes::Aes256, U12>::new(&key);

                Ok(Self::IvAes256Gcm(cipher, key))
            }
        }
    }

    #[inline]
    pub fn algorithm(&self) -> DatCryptoAlgorithm {
        match self {
            Self::IvAes128Gcm(_, _) => IvAes128Gcm,
            Self::IvAes256Gcm(_, _) => IvAes256Gcm,
        }
    }

    pub fn export_key(&self) -> Box<[u8]> {
        match self {
            Self::IvAes128Gcm(_, key) => Box::from(key.as_slice()),
            Self::IvAes256Gcm(_, key) => Box::from(key.as_slice()),
        }
    }

    #[inline]
    pub fn key_base64_len(&self) -> usize {
        match self {
            Self::IvAes128Gcm(_, _) => 22,
            Self::IvAes256Gcm(_, _) => 43,
        }
    }

    pub fn encrypt(&self, body: &[u8]) -> Result<Vec<u8>, DatError> {
        if body.is_empty() {
            return Ok(vec![]);
        }
        let iv: Array<u8, U12> = Nonce::generate();
        let mut enc_data = Vec::with_capacity(IV_LEN + body.len() + TAG_LEN);
        enc_data.extend_from_slice(&iv);
        enc_data.extend_from_slice(body);

        let inout = InOutBuf::from(&mut enc_data[IV_LEN..]);

        let tag = match self {
            Self::IvAes128Gcm(cipher, _) => cipher.encrypt_inout_detached(&iv, &[], inout),
            Self::IvAes256Gcm(cipher, _) => cipher.encrypt_inout_detached(&iv, &[], inout),
        }.map_err(|_| DatError::EncryptError)?;

        enc_data.extend_from_slice(&tag.as_slice());

        Ok(enc_data)
    }

    pub fn decrypt(&self, mut data: Vec<u8>) -> Result<Vec<u8>, DatError> {
        if data.is_empty() {
            return Ok(Vec::with_capacity(0));
        }
        if data.len() <= IV_LEN {
            return Err(DatError::DecryptError);
        }
        let mut secure = data.split_off(IV_LEN);

        match self {
            Self::IvAes128Gcm(cipher, _) => {
                AeadInOut::decrypt_in_place(cipher, data.as_slice().try_into().map_err(|_| DatError::DecryptError)?, &[], &mut secure)
            },
            Self::IvAes256Gcm(cipher, _) => {
                AeadInOut::decrypt_in_place(cipher, data.as_slice().try_into().map_err(|_| DatError::DecryptError)?, &[], &mut secure)
            },
        }.map_err(|_| DatError::DecryptError)?;

        Ok(secure)
    }
}