@Override
  public boolean equalsKey(Key other) {
    if (!(other instanceof PrfBasedKeyDerivationKey)) {
      return false;
    }

    PrfBasedKeyDerivationKey otherKey = (PrfBasedKeyDerivationKey) other;
    return otherKey.getParameters().equals(getParameters())
        && otherKey.prfKey.equalsKey(prfKey)
        && Objects.equals(otherKey.idRequirementOrNull, idRequirementOrNull);
  }
Represents a Derivation key which is based on a PRF.

<p>An object of this class represents the map which 1) uses the given PRF (as specified by {@link
#getPrfKey}) to get sufficient key material from the salt, then 2) creates a key for the
parameters as specified in {@code getParameters().getDerivedKeyParameters()}.
java_src/src/main/java/com/google/crypto/tink/keyderivation/PrfBasedKeyDerivationKey.java