fix: normalize signature v value for proper recovery

[cloudonshore]

Summary

Ledger devices may return signature v as 0 or 1 (modern format), but Ethereum's ecrecover expects 27 or 28 (Yellow Paper §F). This causes "The signature doesnt match the right address" errors in signPersonalMessage and signTypedData.

Fix

if (v === 0 || v === 1) {
  v += 27;
}

Why This Wasn't Fixed Before

Original bug (pre-2022): The code subtracted 27 from v:

let v = payload.v - 27  // WRONG

This converted correct values (27/28) into incorrect ones (0/1).

PR #152 (August 2022): Changed to pass through the raw value:

let v = parseInt(payload.v, 10)  // Just pass through

This fixed the case where Ledger returns 27/28, but assumed Ledger always returns 27/28.

The gap: Ledger devices may return 0/1 depending on firmware, signing method, or device model. PR #152 didn't normalize these values.

Issue #10850 was closed prematurely in January 2024 with "I expect this was resolved in PR #152" — but PR #152 only fixed one direction of the problem.

References

This is a well-known issue with a standard fix across the ecosystem:

• Frame wallet - v = v === 0 || v === 1 ? v + 27 : v
• Rabby wallet - "Metamask with ledger returns V=0/1 here too"
• Gnosis Safe Android - if (v <= 1) v += 27
• Related issues: #134, #151, metamask-extension#10850

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Note

Medium Risk
Touches signature construction/verification in signPersonalMessage and signTypedData, which can affect whether Ledger-signed messages are accepted or rejected. Change is small and well-covered by new tests, but it impacts crypto-critical signing paths.

Overview
Fixes Ledger message signing compatibility by normalizing returned v values: when the device returns 0/1, the keyring now converts them to 27/28 before building the 0x{r}{s}{v} signature in signPersonalMessage and signTypedData.

Updates tests to cover v normalization for 0/1 and to ensure 27/28 are preserved, adjusting expected signature suffixes and validating address recovery behavior.

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