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

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// This file contains code that was copied from the ring crate which is under
// the ISC license, reproduced below:

// Copyright 2015-2017 Brian Smith.

// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.

// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

use crate::{aead, error::*};
use nss::aes;

/// AES-128 in GCM mode with 128-bit tags and 96 bit nonces.
pub static AES_128_GCM: aead::Algorithm = aead::Algorithm {
    key_len: 16,
    tag_len: 16,
    nonce_len: 96 / 8,
    open,
    seal,
};

/// AES-256 in GCM mode with 128-bit tags and 96 bit nonces.
pub static AES_256_GCM: aead::Algorithm = aead::Algorithm {
    key_len: 32,
    tag_len: 16,
    nonce_len: 96 / 8,
    open,
    seal,
};

pub(crate) fn open(
    key: &aead::Key,
    nonce: aead::Nonce,
    aad: &aead::Aad<'_>,
    ciphertext_and_tag: &[u8],
) -> Result<Vec<u8>> {
    aes_gcm(
        key,
        nonce,
        aad,
        ciphertext_and_tag,
        aead::Direction::Opening,
    )
}

pub(crate) fn seal(
    key: &aead::Key,
    nonce: aead::Nonce,
    aad: &aead::Aad<'_>,
    plaintext: &[u8],
) -> Result<Vec<u8>> {
    aes_gcm(key, nonce, aad, plaintext, aead::Direction::Sealing)
}

fn aes_gcm(
    key: &aead::Key,
    nonce: aead::Nonce,
    aad: &aead::Aad<'_>,
    data: &[u8],
    direction: aead::Direction,
) -> Result<Vec<u8>> {
    Ok(aes::aes_gcm_crypt(
        &key.key_value,
        &nonce.0,
        &aad.0,
        data,
        direction.to_nss_operation(),
    )?)
}

#[cfg(test)]
mod test {
    use super::*;

    // Test vector from the AES-GCM spec.
    const NONCE_HEX: &str = "cafebabefacedbaddecaf888";
    const KEY_HEX: &str = "feffe9928665731c6d6a8f9467308308feffe9928665731c6d6a8f9467308308";
    const AAD_HEX: &str = "feedfacedeadbeeffeedfacedeadbeefabaddad2";
    const TAG_HEX: &str = "76fc6ece0f4e1768cddf8853bb2d551b";
    const CIPHERTEXT_HEX: &str =
        "522dc1f099567d07f47f37a32a84427d643a8cdcbfe5c0c97598a2bd2555d1aa8cb08e48590dbb3da7b08b1056828838c5f61e6393ba7a0abcc9f662";
    const CLEARTEXT_HEX: &str =
        "d9313225f88406e5a55909c5aff5269a86a7a9531534f7da2e4c303d8a318a721c3c0c95956809532fcf0e2449a6b525b16aedf5aa0de657ba637b39";

    #[test]
    fn test_decrypt() {
        let key_bytes = hex::decode(KEY_HEX).unwrap();
        let key = aead::Key::new(&AES_256_GCM, &key_bytes).unwrap();
        let mut ciphertext_and_tag = hex::decode(&CIPHERTEXT_HEX).unwrap();
        let tag = hex::decode(&TAG_HEX).unwrap();
        ciphertext_and_tag.extend(&tag);

        let iv = hex::decode(NONCE_HEX).unwrap();
        let nonce = aead::Nonce::try_assume_unique_for_key(&AES_256_GCM, &iv).unwrap();
        let aad_bytes = hex::decode(AAD_HEX).unwrap();
        let aad = aead::Aad::from(&aad_bytes);
        let cleartext_bytes = open(&key, nonce, &aad, &ciphertext_and_tag).unwrap();
        let encoded_cleartext = hex::encode(cleartext_bytes);
        assert_eq!(&CLEARTEXT_HEX, &encoded_cleartext);
    }

    #[test]
    fn test_encrypt() {
        let key_bytes = hex::decode(KEY_HEX).unwrap();
        let key = aead::Key::new(&AES_256_GCM, &key_bytes).unwrap();
        let cleartext = hex::decode(&CLEARTEXT_HEX).unwrap();

        let iv = hex::decode(NONCE_HEX).unwrap();
        let nonce = aead::Nonce::try_assume_unique_for_key(&AES_256_GCM, &iv).unwrap();
        let aad_bytes = hex::decode(AAD_HEX).unwrap();
        let aad = aead::Aad::from(&aad_bytes);
        let ciphertext_bytes = seal(&key, nonce, &aad, &cleartext).unwrap();

        let expected_tag = hex::decode(&TAG_HEX).unwrap();
        let mut expected_ciphertext = hex::decode(&CIPHERTEXT_HEX).unwrap();
        expected_ciphertext.extend(&expected_tag);
        assert_eq!(&expected_ciphertext, &ciphertext_bytes);
    }

    #[test]
    fn test_roundtrip() {
        let key_bytes = hex::decode(KEY_HEX).unwrap();
        let key = aead::Key::new(&AES_256_GCM, &key_bytes).unwrap();
        let cleartext = hex::decode(&CLEARTEXT_HEX).unwrap();

        let iv = hex::decode(NONCE_HEX).unwrap();
        let nonce = aead::Nonce::try_assume_unique_for_key(&AES_256_GCM, &iv).unwrap();
        let ciphertext_bytes = seal(&key, nonce, &aead::Aad::empty(), &cleartext).unwrap();
        let nonce = aead::Nonce::try_assume_unique_for_key(&AES_256_GCM, &iv).unwrap();
        let roundtriped_cleartext_bytes =
            open(&key, nonce, &aead::Aad::empty(), &ciphertext_bytes).unwrap();
        assert_eq!(roundtriped_cleartext_bytes, cleartext);
    }
}