n0-computer/iroh · info

slice with incorrect length

Error message

slice with incorrect length

What it means

PublicKey::fmt_short slices the key's 32 bytes to the first 5 and converts to a fixed-size array for a short hex display, expecting "slice with incorrect length" never to fire. The panic is impossible at runtime because the slice bounds [0..5] are hardcoded to 5 bytes, matching the target array length; it exists only to satisfy the compiler's try_into Result.

Solutions

1. No runtime action required; the expect documents a guaranteed-length slice.
2. If changing key representation, update both the slice range and the array size together, or handle try_into's error explicitly.
3. Keep unit tests asserting fmt_short output length to catch such regressions.

// Not applicable for users: fmt_short cannot panic; nothing to pre-validate.
null

When it happens

Trigger: Not reachable: `self.0.as_bytes()[0..5]` always yields exactly 5 bytes (keys are 32 bytes), so try_into into the 5-byte array always succeeds. Reachable only if key size or the slice range is changed in a refactor.

Common situations: Seen when reading/refactoring key.rs; a runtime panic here would mean PublicKey no longer holds 32 bytes or the literal range was edited.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

• data length checked above
• already verified

AI-assisted analysis of n0-computer/iroh@2b4de030ce (2026-09-08). Data as JSON: /api/errors/407bdee41651f877. Report an issue: GitHub.

Appendix: source

Thrown at iroh-base/src/key.rs:146

    /// Verify a signature on a message with this public key.
    ///
    /// # Return
    ///
    /// Returns `Ok(())` if the signature is valid, and `Err` otherwise.
    pub fn verify(&self, message: &[u8], signature: &Signature) -> Result<(), SignatureError> {
        self.as_verifying_key()
            .verify_strict(message, &signature.0)
            .map_err(|_| SignatureError::new())
    }

    /// Convert to a hex string limited to the first 5 bytes for a friendly string
    /// representation of the key.
    pub fn fmt_short(&self) -> impl Display + Copy + 'static {
        PublicKeyShort(
            self.0.as_bytes()[0..5]
                .try_into()
                .expect("slice with incorrect length"),
        )
    }

    /// Needed for internal conversions, not part of the stable API.
    #[doc(hidden)]
    pub fn as_verifying_key(&self) -> VerifyingKey {
        VerifyingKey::from_bytes(self.0.as_bytes()).expect("already verified")
    }

    /// Needed for internal conversions, not part of the stable API.
    #[doc(hidden)]
    pub fn from_verifying_key(key: VerifyingKey) -> Self {
        Self(CompressedEdwardsY(key.to_bytes()))
    }

    /// Encodes this key in [z-base-32](https://philzimmermann.com/docs/human-oriented-base-32-encoding.txt),
    /// the encoding used by [pkarr](https://pkarr.org) domain names.
    pub fn to_z32(&self) -> String {

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