ring 0.3.1

Safe, fast, small crypto using Rust.
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
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

// Copyright 2015-2016 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.

#![allow(unsafe_code)]

//! EdDSA Signatures.

use {bssl, c, error, private, rand, signature};
use untrusted;

/// Parameters for EdDSA signing and verification.
pub struct EdDSAParameters;

/// An Ed25519 key pair, for signing.
pub struct Ed25519KeyPair {
    private_public: [u8; 64],
}

/// The raw bytes of the Ed25519 key pair, for serialization.
pub struct Ed25519KeyPairBytes {
    /// Private key bytes.
    pub private_key: [u8; 32],

    /// Public key bytes.
    pub public_key: [u8; 32],
}

impl<'a> Ed25519KeyPair {
    /// Generates a new random key pair. There is no way to extract the private
    /// key bytes to save them. If you need to save the private key bytes for
    /// future use then use `generate_serializable()` instead.
    pub fn generate(rng: &rand::SecureRandom)
                    -> Result<Ed25519KeyPair, error::Unspecified> {
        Ed25519KeyPair::generate_serializable(rng)
            .map(|(key_pair, _)| key_pair)
    }

    /// Generates a new key pair and returns the key pair as both an
    /// `Ed25519KeyPair` and a `Ed25519KeyPairBytes`. There is no way to
    /// extract the private key bytes from an `Ed25519KeyPair`, so extracting
    /// the values from the `Ed25519KeyPairBytes` is the only way to get them.
    pub fn generate_serializable(rng: &rand::SecureRandom)
            -> Result<(Ed25519KeyPair, Ed25519KeyPairBytes),
                      error::Unspecified> {
        let mut bytes = Ed25519KeyPairBytes {
            private_key: [0; 32],
            public_key: [0; 32],
        };
        try!(rng.fill(&mut bytes.private_key));
        unsafe {
            GFp_ed25519_public_from_private(bytes.public_key.as_mut_ptr(),
                                            bytes.private_key.as_ptr());
        }
        let key_pair =
            try!(Ed25519KeyPair::from_bytes_unchecked(&bytes.private_key,
                                                      &bytes.public_key));
        Ok((key_pair, bytes))
    }

    /// Copies key data from the given slices to create a new key pair. The
    /// first slice must hold the private key and the second slice must hold
    /// the public key. Both slices must contain 32 little-endian-encoded
    /// bytes.
    ///
    /// This is intended for use by code that deserializes key pairs.
    ///
    /// The private and public keys will be verified to be consistent. This
    /// helps protect, for example, against the accidental swapping of the
    /// public and private components of the key pair. This also detects
    /// corruption that might have occurred during storage of the key pair.
    pub fn from_bytes(private_key: &[u8], public_key: &[u8])
                      -> Result<Ed25519KeyPair, error::Unspecified> {
        let pair =
            try!(Ed25519KeyPair::from_bytes_unchecked(private_key, public_key));
        let mut public_key_check = [0; 32];
        unsafe {
            GFp_ed25519_public_from_private(public_key_check.as_mut_ptr(),
                                            pair.private_public.as_ptr());
        }
        if public_key != public_key_check {
            return Err(error::Unspecified);
        }
        Ok(pair)
    }

    fn from_bytes_unchecked(private_key: &[u8], public_key: &[u8])
                            -> Result<Ed25519KeyPair, error::Unspecified> {
        if private_key.len() != 32 {
            return Err(error::Unspecified);
        }
        if public_key.len() != 32 {
            return Err(error::Unspecified);
        }
        let mut pair = Ed25519KeyPair { private_public: [0; 64] };
        for i in 0..32 {
            pair.private_public[i] = private_key[i];
            pair.private_public[32 + i] = public_key[i];
        }
        Ok(pair)
    }

    /// Returns a reference to the little-endian-encoded public key bytes.
    pub fn public_key_bytes(&'a self) -> &'a [u8] {
        &self.private_public[32..]
    }

    /// Returns the signature of the message `msg`.
    pub fn sign(&self, msg: &[u8]) -> signature::Signature {
        let mut signature_bytes = [0u8; 64];
        unsafe {
            GFp_ed25519_sign(signature_bytes.as_mut_ptr(), msg.as_ptr(),
                             msg.len(), self.private_public.as_ptr());
        }
        signature::Signature::new(signature_bytes)
    }
}


/// Verification of [Ed25519] signatures.
///
/// Ed25519 uses SHA-512 as the digest algorithm.
///
/// [Ed25519]: https://ed25519.cr.yp.to/
pub static ED25519: EdDSAParameters = EdDSAParameters { };

impl signature::VerificationAlgorithm for EdDSAParameters {
    fn verify(&self, public_key: untrusted::Input, msg: untrusted::Input,
              signature: untrusted::Input) -> Result<(), error::Unspecified> {
        let public_key = public_key.as_slice_less_safe();
        if public_key.len() != 32 || signature.len() != 64 {
            return Err(error::Unspecified);
        }
        let msg = msg.as_slice_less_safe();
        let signature = signature.as_slice_less_safe();
        bssl::map_result(unsafe {
            GFp_ed25519_verify(msg.as_ptr(), msg.len(), signature.as_ptr(),
                               public_key.as_ptr())
        })
    }
}

impl private::Private for EdDSAParameters { }


extern  {
    fn GFp_ed25519_public_from_private(out: *mut u8/*[32]*/,
                                       in_: *const u8/*[32]*/);

    fn GFp_ed25519_sign(out_sig: *mut u8/*[64]*/, message: *const u8,
                        message_len: c::size_t, private_key: *const u8/*[64]*/);

    fn GFp_ed25519_verify(message: *const u8, message_len: c::size_t,
                          signature: *const u8/*[64]*/,
                          public_key: *const u8/*[32]*/) -> c::int;
}


#[cfg(test)]
mod tests {
    use {test, rand, signature};
    use super::Ed25519KeyPair;
    use untrusted;

    /// Test vectors from BoringSSL.
    #[test]
    fn test_signature_ed25519() {
        test::from_file("src/ec/ed25519_tests.txt", |section, test_case| {
            assert_eq!(section, "");
            let private_key = test_case.consume_bytes("PRIV");
            assert_eq!(64, private_key.len());
            let public_key = test_case.consume_bytes("PUB");
            assert_eq!(32, public_key.len());
            let msg = test_case.consume_bytes("MESSAGE");
            let expected_sig = test_case.consume_bytes("SIG");

            let key_pair = Ed25519KeyPair::from_bytes(&private_key[..32],
                                                      &public_key).unwrap();
            let actual_sig = key_pair.sign(&msg);
            assert_eq!(&expected_sig[..], actual_sig.as_slice());

            let public_key = untrusted::Input::from(&public_key);
            let msg = untrusted::Input::from(&msg);
            let expected_sig = untrusted::Input::from(&expected_sig);

            assert!(signature::verify(&signature::ED25519, public_key,
                                      msg, expected_sig).is_ok());

            Ok(())
        });
    }

    #[test]
    fn test_ed25519_from_bytes_misuse() {
        let rng = rand::SystemRandom::new();
        let (_, bytes) =
            Ed25519KeyPair::generate_serializable(&rng).unwrap();

        assert!(Ed25519KeyPair::from_bytes(&bytes.private_key,
                                           &bytes.public_key).is_ok());

        // Truncated private key.
        assert!(Ed25519KeyPair::from_bytes(&bytes.private_key[..31],
                                           &bytes.public_key).is_err());

        // Truncated public key.
        assert!(Ed25519KeyPair::from_bytes(&bytes.private_key,
                                           &bytes.public_key[..31]).is_err());

        // Swapped public and private key.
        assert!(Ed25519KeyPair::from_bytes(&bytes.public_key,
                                           &bytes.private_key).is_err());
    }
}