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Signal Protocol cryptography library for Java

There is a newer version: 0.62.0

//
// Copyright 2016 Signal Messenger, LLC.
// SPDX-License-Identifier: AGPL-3.0-only
//

package org.signal.libsignal.protocol.fingerprint;

import static org.signal.libsignal.internal.FilterExceptions.filterExceptions;

import org.signal.libsignal.internal.Native;
import org.signal.libsignal.protocol.IdentityKey;

public class NumericFingerprintGenerator implements FingerprintGenerator {
  private final int iterations;

  /**
   * Construct a fingerprint generator for 60 digit numerics.
   *
   * @param iterations The number of internal iterations to perform in the process of generating a
   *     fingerprint. This needs to be constant, and synchronized across all clients.
   *     The higher the iteration count, the higher the security level:
   *     

   *       1024 ~ 109.7 bits
   *       
1400 > 110 bits
   *       
5200 > 112 bits
   *     
   */
  public NumericFingerprintGenerator(int iterations) {
    this.iterations = iterations;
  }

  /**
   * Generate a scannable and displayable fingerprint.
   *
   * @param version The version of fingerprint you are generating.
   * @param localStableIdentifier The client's "stable" identifier.
   * @param localIdentityKey The client's identity key.
   * @param remoteStableIdentifier The remote party's "stable" identifier.
   * @param remoteIdentityKey The remote party's identity key.
   * @return A unique fingerprint for this conversation.
   */
  @Override
  public Fingerprint createFor(
      int version,
      byte[] localStableIdentifier,
      final IdentityKey localIdentityKey,
      byte[] remoteStableIdentifier,
      final IdentityKey remoteIdentityKey) {

    return filterExceptions(
        () -> {
          long handle =
              Native.NumericFingerprintGenerator_New(
                  this.iterations,
                  version,
                  localStableIdentifier,
                  localIdentityKey.serialize(),
                  remoteStableIdentifier,
                  remoteIdentityKey.serialize());

          DisplayableFingerprint displayableFingerprint =
              new DisplayableFingerprint(
                  Native.NumericFingerprintGenerator_GetDisplayString(handle));

          ScannableFingerprint scannableFingerprint =
              new ScannableFingerprint(
                  Native.NumericFingerprintGenerator_GetScannableEncoding(handle));

          Native.NumericFingerprintGenerator_Destroy(handle);

          return new Fingerprint(displayableFingerprint, scannableFingerprint);
        });
  }
}