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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
//! Low level AES IGE and key wrapping functionality
//!
//! AES ECB, CBC, XTS, CTR, CFB, GCM and other conventional symmetric encryption
//! modes are found in [`symm`].  This is the implementation of AES IGE and key wrapping
//!
//! Advanced Encryption Standard (AES) provides symmetric key cipher that
//! the same key is used to encrypt and decrypt data.  This implementation
//! uses 128, 192, or 256 bit keys.  This module provides functions to
//! create a new key with [`new_encrypt`] and perform an encryption/decryption
//! using that key with [`aes_ige`].
//!
//! [`new_encrypt`]: struct.AesKey.html#method.new_encrypt
//! [`aes_ige`]: fn.aes_ige.html
//!
//! The [`symm`] module should be used in preference to this module in most cases.
//! The IGE block cypher is a non-traditional cipher mode.  More traditional AES
//! encryption methods are found in the [`Crypter`] and [`Cipher`] structs.
//!
//! [`symm`]: ../symm/index.html
//! [`Crypter`]: ../symm/struct.Crypter.html
//! [`Cipher`]: ../symm/struct.Cipher.html
//!
//! # Examples
//!
//! ## AES IGE
//! ```rust
//! use openssl::aes::{AesKey, aes_ige};
//! use openssl::symm::Mode;
//!
//! let key = b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F";
//! let plaintext = b"\x12\x34\x56\x78\x90\x12\x34\x56\x12\x34\x56\x78\x90\x12\x34\x56";
//! let mut iv = *b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\
//!                 \x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F";
//!
//!  let key = AesKey::new_encrypt(key).unwrap();
//!  let mut output = [0u8; 16];
//!  aes_ige(plaintext, &mut output, &key, &mut iv, Mode::Encrypt);
//!  assert_eq!(output, *b"\xa6\xad\x97\x4d\x5c\xea\x1d\x36\xd2\xf3\x67\x98\x09\x07\xed\x32");
//! ```
//!
//! ## Key wrapping
//! ```rust
//! use openssl::aes::{AesKey, unwrap_key, wrap_key};
//!
//! let kek = b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F";
//! let key_to_wrap = b"\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xAA\xBB\xCC\xDD\xEE\xFF";
//!
//! let enc_key = AesKey::new_encrypt(kek).unwrap();
//! let mut ciphertext = [0u8; 24];
//! wrap_key(&enc_key, None, &mut ciphertext, &key_to_wrap[..]).unwrap();
//! let dec_key = AesKey::new_decrypt(kek).unwrap();
//! let mut orig_key = [0u8; 16];
//! unwrap_key(&dec_key, None, &mut orig_key, &ciphertext[..]).unwrap();
//!
//! assert_eq!(&orig_key[..], &key_to_wrap[..]);
//! ```
//!
use ffi;
use libc::{c_int, c_uint};
use std::{mem, ptr};

use symm::Mode;

/// Provides Error handling for parsing keys.
#[derive(Debug)]
pub struct KeyError(());

/// The key used to encrypt or decrypt cipher blocks.
pub struct AesKey(ffi::AES_KEY);

impl AesKey {
    /// Prepares a key for encryption.
    ///
    /// # Failure
    ///
    /// Returns an error if the key is not 128, 192, or 256 bits.
    #[allow(deprecated)] // https://github.com/rust-lang/rust/issues/63566
    pub fn new_encrypt(key: &[u8]) -> Result<AesKey, KeyError> {
        unsafe {
            assert!(key.len() <= c_int::max_value() as usize / 8);

            let mut aes_key = mem::uninitialized();
            let r = ffi::AES_set_encrypt_key(
                key.as_ptr() as *const _,
                key.len() as c_int * 8,
                &mut aes_key,
            );
            if r == 0 {
                Ok(AesKey(aes_key))
            } else {
                Err(KeyError(()))
            }
        }
    }

    /// Prepares a key for decryption.
    ///
    /// # Failure
    ///
    /// Returns an error if the key is not 128, 192, or 256 bits.
    #[allow(deprecated)] // https://github.com/rust-lang/rust/issues/63566
    pub fn new_decrypt(key: &[u8]) -> Result<AesKey, KeyError> {
        unsafe {
            assert!(key.len() <= c_int::max_value() as usize / 8);

            let mut aes_key = mem::uninitialized();
            let r = ffi::AES_set_decrypt_key(
                key.as_ptr() as *const _,
                key.len() as c_int * 8,
                &mut aes_key,
            );

            if r == 0 {
                Ok(AesKey(aes_key))
            } else {
                Err(KeyError(()))
            }
        }
    }
}

/// Performs AES IGE encryption or decryption
///
/// AES IGE (Infinite Garble Extension) is a form of AES block cipher utilized in
/// OpenSSL.  Infinite Garble referes to propogating forward errors.  IGE, like other
/// block ciphers implemented for AES requires an initalization vector.  The IGE mode
/// allows a stream of blocks to be encrypted or decrypted without having the entire
/// plaintext available.  For more information, visit [AES IGE Encryption].
///
/// This block cipher uses 16 byte blocks.  The rust implmentation will panic
/// if the input or output does not meet this 16-byte boundry.  Attention must
/// be made in this low level implementation to pad the value to the 128-bit boundry.
///
/// [AES IGE Encryption]: http://www.links.org/files/openssl-ige.pdf
///
/// # Panics
///
/// Panics if `in_` is not the same length as `out`, if that length is not a multiple of 16, or if
/// `iv` is not at least 32 bytes.
pub fn aes_ige(in_: &[u8], out: &mut [u8], key: &AesKey, iv: &mut [u8], mode: Mode) {
    unsafe {
        assert!(in_.len() == out.len());
        assert!(in_.len() % ffi::AES_BLOCK_SIZE as usize == 0);
        assert!(iv.len() >= ffi::AES_BLOCK_SIZE as usize * 2);

        let mode = match mode {
            Mode::Encrypt => ffi::AES_ENCRYPT,
            Mode::Decrypt => ffi::AES_DECRYPT,
        };
        ffi::AES_ige_encrypt(
            in_.as_ptr() as *const _,
            out.as_mut_ptr() as *mut _,
            in_.len(),
            &key.0,
            iv.as_mut_ptr() as *mut _,
            mode,
        );
    }
}

/// Wrap a key, according to [RFC 3394](https://tools.ietf.org/html/rfc3394)
///
/// * `key`: The key-encrypting-key to use. Must be a encrypting key
/// * `iv`: The IV to use. You must use the same IV for both wrapping and unwrapping
/// * `out`: The output buffer to store the ciphertext
/// * `in_`: The input buffer, storing the key to be wrapped
///
/// Returns the number of bytes written into `out`
///
/// # Panics
///
/// Panics if either `out` or `in_` do not have sizes that are a multiple of 8, or if
/// `out` is not 8 bytes longer than `in_`
pub fn wrap_key(
    key: &AesKey,
    iv: Option<[u8; 8]>,
    out: &mut [u8],
    in_: &[u8],
) -> Result<usize, KeyError> {
    unsafe {
        assert!(out.len() >= in_.len() + 8); // Ciphertext is 64 bits longer (see 2.2.1)

        let written = ffi::AES_wrap_key(
            &key.0 as *const _ as *mut _, // this is safe, the implementation only uses the key as a const pointer.
            iv.as_ref()
                .map_or(ptr::null(), |iv| iv.as_ptr() as *const _),
            out.as_ptr() as *mut _,
            in_.as_ptr() as *const _,
            in_.len() as c_uint,
        );
        if written <= 0 {
            Err(KeyError(()))
        } else {
            Ok(written as usize)
        }
    }
}

/// Unwrap a key, according to [RFC 3394](https://tools.ietf.org/html/rfc3394)
///
/// * `key`: The key-encrypting-key to decrypt the wrapped key. Must be a decrypting key
/// * `iv`: The same IV used for wrapping the key
/// * `out`: The buffer to write the unwrapped key to
/// * `in_`: The input ciphertext
///
/// Returns the number of bytes written into `out`
///
/// # Panics
///
/// Panics if either `out` or `in_` do not have sizes that are a multiple of 8, or
/// if `in` is not 8 bytes longer than `in_`
pub fn unwrap_key(
    key: &AesKey,
    iv: Option<[u8; 8]>,
    out: &mut [u8],
    in_: &[u8],
) -> Result<usize, KeyError> {
    unsafe {
        assert!(out.len() + 8 <= in_.len());

        let written = ffi::AES_unwrap_key(
            &key.0 as *const _ as *mut _, // this is safe, the implementation only uses the key as a const pointer.
            iv.as_ref()
                .map_or(ptr::null(), |iv| iv.as_ptr() as *const _),
            out.as_ptr() as *mut _,
            in_.as_ptr() as *const _,
            in_.len() as c_uint,
        );

        if written <= 0 {
            Err(KeyError(()))
        } else {
            Ok(written as usize)
        }
    }
}

#[cfg(test)]
mod test {
    use hex::FromHex;

    use super::*;
    use symm::Mode;

    // From https://www.mgp25.com/AESIGE/
    #[test]
    fn ige_vector_1() {
        let raw_key = "000102030405060708090A0B0C0D0E0F";
        let raw_iv = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F";
        let raw_pt = "0000000000000000000000000000000000000000000000000000000000000000";
        let raw_ct = "1A8519A6557BE652E9DA8E43DA4EF4453CF456B4CA488AA383C79C98B34797CB";

        let key = AesKey::new_encrypt(&Vec::from_hex(raw_key).unwrap()).unwrap();
        let mut iv = Vec::from_hex(raw_iv).unwrap();
        let pt = Vec::from_hex(raw_pt).unwrap();
        let ct = Vec::from_hex(raw_ct).unwrap();

        let mut ct_actual = vec![0; ct.len()];
        aes_ige(&pt, &mut ct_actual, &key, &mut iv, Mode::Encrypt);
        assert_eq!(ct_actual, ct);

        let key = AesKey::new_decrypt(&Vec::from_hex(raw_key).unwrap()).unwrap();
        let mut iv = Vec::from_hex(raw_iv).unwrap();
        let mut pt_actual = vec![0; pt.len()];
        aes_ige(&ct, &mut pt_actual, &key, &mut iv, Mode::Decrypt);
        assert_eq!(pt_actual, pt);
    }

    // from the RFC https://tools.ietf.org/html/rfc3394#section-2.2.3
    #[test]
    fn test_wrap_unwrap() {
        let raw_key = Vec::from_hex("000102030405060708090A0B0C0D0E0F").unwrap();
        let key_data = Vec::from_hex("00112233445566778899AABBCCDDEEFF").unwrap();
        let expected_ciphertext =
            Vec::from_hex("1FA68B0A8112B447AEF34BD8FB5A7B829D3E862371D2CFE5").unwrap();

        let enc_key = AesKey::new_encrypt(&raw_key).unwrap();
        let mut wrapped = [0; 24];
        assert_eq!(
            wrap_key(&enc_key, None, &mut wrapped, &key_data).unwrap(),
            24
        );
        assert_eq!(&wrapped[..], &expected_ciphertext[..]);

        let dec_key = AesKey::new_decrypt(&raw_key).unwrap();
        let mut unwrapped = [0; 16];
        assert_eq!(
            unwrap_key(&dec_key, None, &mut unwrapped, &wrapped).unwrap(),
            16
        );
        assert_eq!(&unwrapped[..], &key_data[..]);
    }
}