PIN management

Set, rotate, verify, and remove the signing PIN.

The PIN gates signMessage, signTransactionHash, and deleteWallet when requirePin: true. It is stored only as a salted PBKDF2-HMAC-SHA256 digest inside flutter_secure_storage — the raw PIN never touches disk.

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Set a PIN

Call setPin once after wallet provisioning. The PIN must be exactly BmoniEmbeddedSdk.pinLength characters (default 6).

await BmoniEmbeddedSdk.setPin('123456');

Throws pinAlreadySet if a PIN already exists. Check first:

if (!await BmoniEmbeddedSdk.hasPin()) {
  await BmoniEmbeddedSdk.setPin('123456');
}

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Check whether a PIN is set

final bool hasPin = await BmoniEmbeddedSdk.hasPin();

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Verify a PIN without throwing

Use matchPin to check a PIN without triggering an exception. Useful for validating a user’s entry before attempting a gated operation.

final bool matches = await BmoniEmbeddedSdk.matchPin('123456');
if (!matches) {
  // Show "Incorrect PIN" to the user.
}

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Change a PIN

Requires the current PIN. Both the current and new PINs must be pinLength characters.

await BmoniEmbeddedSdk.changePin(
  currentPin: '123456',
  newPin: '654321',
);

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Remove a PIN

Removes the stored digest entirely. After removal, hasPin() returns false and PIN-gated operations are unavailable until a new PIN is set.

await BmoniEmbeddedSdk.removePin('123456');

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PIN length enforcement

All PIN operations enforce the pinLength set in BmoniEmbeddedSdk.initialize. Passing a PIN of the wrong length throws BmoniSignerException(errorCode: pinInvalid).

You can read the required length at runtime to drive your UI:

final int requiredLength = BmoniEmbeddedSdk.pinLength; // 6 by default

TextField(
  maxLength: requiredLength,
  keyboardType: TextInputType.number,
  // ...
)

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Full example

// 1. One-time setup.
await BmoniEmbeddedSdk.setPin('123456');

// 2. Rotate the PIN.
await BmoniEmbeddedSdk.changePin(
  currentPin: '123456',
  newPin: '654321',
);

// 3. Verify without throwing — useful for a PIN confirmation step.
final bool ok = await BmoniEmbeddedSdk.matchPin('654321');
print('PIN matches: $ok'); // true

// 4. Tear down (e.g. on logout).
await BmoniEmbeddedSdk.removePin('654321');