signature/
error.rs

1//! Signature error types
2
3use core::fmt::{self, Debug, Display};
4
5#[cfg(feature = "std")]
6use std::boxed::Box;
7
8/// Result type.
9///
10/// A result with the `signature` crate's [`Error`] type.
11pub type Result<T> = core::result::Result<T, Error>;
12
13/// Signature errors.
14///
15/// This type is deliberately opaque as to avoid sidechannel leakage which
16/// could potentially be used recover signing private keys or forge signatures
17/// (e.g. [BB'06]).
18///
19/// When the `std` feature is enabled, it impls [`std::error::Error`] and
20/// supports an optional [`std::error::Error::source`], which can be used by
21/// things like remote signers (e.g. HSM, KMS) to report I/O or auth errors.
22///
23/// [BB'06]: https://en.wikipedia.org/wiki/Daniel_Bleichenbacher
24#[derive(Default)]
25#[non_exhaustive]
26pub struct Error {
27    /// Source of the error (if applicable).
28    #[cfg(feature = "std")]
29    source: Option<Box<dyn std::error::Error + Send + Sync + 'static>>,
30}
31
32impl Error {
33    /// Create a new error with no associated source
34    pub fn new() -> Self {
35        Self::default()
36    }
37
38    /// Create a new error with an associated source.
39    ///
40    /// **NOTE:** The "source" should **NOT** be used to propagate cryptographic
41    /// errors e.g. signature parsing or verification errors. The intended use
42    /// cases are for propagating errors related to external signers, e.g.
43    /// communication/authentication errors with HSMs, KMS, etc.
44    #[cfg(feature = "std")]
45    pub fn from_source(
46        source: impl Into<Box<dyn std::error::Error + Send + Sync + 'static>>,
47    ) -> Self {
48        Self {
49            source: Some(source.into()),
50        }
51    }
52}
53
54impl Debug for Error {
55    #[cfg(not(feature = "std"))]
56    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
57        f.write_str("signature::Error {}")
58    }
59
60    #[cfg(feature = "std")]
61    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
62        f.write_str("signature::Error { source: ")?;
63
64        if let Some(source) = &self.source {
65            write!(f, "Some({})", source)?;
66        } else {
67            f.write_str("None")?;
68        }
69
70        f.write_str(" }")
71    }
72}
73
74impl Display for Error {
75    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
76        f.write_str("signature error")?;
77
78        #[cfg(feature = "std")]
79        {
80            if let Some(source) = &self.source {
81                write!(f, ": {}", source)?;
82            }
83        }
84
85        Ok(())
86    }
87}
88
89#[cfg(feature = "std")]
90impl From<Box<dyn std::error::Error + Send + Sync + 'static>> for Error {
91    fn from(source: Box<dyn std::error::Error + Send + Sync + 'static>) -> Error {
92        Self::from_source(source)
93    }
94}
95
96#[cfg(feature = "rand_core")]
97impl From<rand_core::Error> for Error {
98    #[cfg(not(feature = "std"))]
99    fn from(_source: rand_core::Error) -> Error {
100        Error::new()
101    }
102
103    #[cfg(feature = "std")]
104    fn from(source: rand_core::Error) -> Error {
105        Error::from_source(source)
106    }
107}
108
109#[cfg(feature = "std")]
110impl std::error::Error for Error {
111    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
112        self.source
113            .as_ref()
114            .map(|source| source.as_ref() as &(dyn std::error::Error + 'static))
115    }
116}
signature/error.rs

signature/
error.rs
