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

//! `Secret<T>` wrapper type for more carefully handling secret values
//! (e.g. passwords, cryptographic keys, access tokens or other credentials)

#![no_std]
#![deny(
    missing_docs,
    rust_2018_idioms,
    trivial_casts,
    unused_lifetimes,
    unused_qualifications
)]
#![forbid(unsafe_code)]
#![doc(html_root_url = "https://docs.rs/secrecy/0.4.0")]

#[cfg(feature = "alloc")]
extern crate alloc;

#[cfg(feature = "alloc")]
mod boxed;
#[cfg(feature = "bytes")]
mod bytes;
#[cfg(feature = "alloc")]
mod string;
#[cfg(feature = "alloc")]
mod vec;

#[cfg(feature = "alloc")]
pub use self::{boxed::SecretBox, string::SecretString, vec::SecretVec};

#[cfg(feature = "bytes")]
pub use self::bytes::{SecretBytes, SecretBytesMut};

use core::fmt::{self, Debug};
#[cfg(feature = "serde")]
use serde::{de, ser, Deserialize, Serialize};
use zeroize::Zeroize;

/// Wrapper type for values that contains secrets, which attempts to limit
/// accidental exposure and ensure secrets are wiped from memory when dropped.
/// (e.g. passwords, cryptographic keys, access tokens or other credentials)
///
/// Access to the secret inner value occurs through the `ExposeSecret` trait,
/// which provides an `expose_secret()` method for accessing the inner secret
/// value.
pub struct Secret<S>
where
    S: Zeroize,
{
    /// Inner secret value
    inner_secret: S,
}

impl<S> Secret<S>
where
    S: Zeroize,
{
    /// Take ownership of a secret value
    pub fn new(secret: S) -> Self {
        Secret {
            inner_secret: secret,
        }
    }
}

impl<S> ExposeSecret<S> for Secret<S>
where
    S: Zeroize,
{
    fn expose_secret(&self) -> &S {
        &self.inner_secret
    }
}

impl<S> Clone for Secret<S>
where
    S: CloneableSecret,
{
    fn clone(&self) -> Self {
        Secret {
            inner_secret: self.inner_secret.clone(),
        }
    }
}

impl<S> Debug for Secret<S>
where
    S: Zeroize + DebugSecret,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "Secret({})", S::debug_secret())
    }
}

impl<S> Drop for Secret<S>
where
    S: Zeroize,
{
    fn drop(&mut self) {
        // Zero the secret out from memory
        self.inner_secret.zeroize();
    }
}

/// Marker trait for secrets which are allowed to be cloned
pub trait CloneableSecret: Clone + Zeroize {}

/// Expose a reference to an inner secret
pub trait ExposeSecret<S> {
    /// Expose secret
    fn expose_secret(&self) -> &S;
}

/// Debugging trait which is specialized for handling secret values
pub trait DebugSecret {
    /// Information about what the secret contains.
    ///
    /// Static so as to discourage unintentional secret exposure.
    fn debug_secret() -> &'static str {
        "R3DACT3D::<GENERIC::S3CR3T"
    }
}

/// Marker trait for secrets which can be serialized directly by `serde`.
/// Since this provides a non-explicit exfiltration path for secrets,
/// types must explicitly opt into this.
///
/// If you are working with a `SecretString`, `SecretVec`, etc. type, they
/// do *NOT* impl this trait by design. Instead, if you really want to have
/// `serde` automatically serialize those types, use the `serialize_with`
/// attribute to specify a serializer that exposes the secret:
///
/// <https://serde.rs/field-attrs.html#serialize_with>
#[cfg(feature = "serde")]
pub trait SerializableSecret: Serialize {}

#[cfg(feature = "serde")]
impl<'de, T> Deserialize<'de> for Secret<T>
where
    T: Zeroize + Clone + DebugSecret + de::DeserializeOwned + Sized,
{
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: de::Deserializer<'de>,
    {
        T::deserialize(deserializer).map(Secret::new)
    }
}

#[cfg(feature = "serde")]
impl<T> Serialize for Secret<T>
where
    T: Zeroize + DebugSecret + Serialize + Sized,
{
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: ser::Serializer,
    {
        self.expose_secret().serialize(serializer)
    }
}