KeyPair GetAsymmetricKeyPair()
{
// set that we generated keys on pre-m device.
Preferences.Set(useSymmetricPreferenceKey, false, SecureStorage.Alias);
var asymmetricAlias = $"{alias}.asymmetric";
var privateKey = keyStore.GetKey(asymmetricAlias, null)?.JavaCast <IPrivateKey>();
var publicKey = keyStore.GetCertificate(asymmetricAlias)?.PublicKey;
// Return the existing key if found
if (privateKey != null && publicKey != null)
{
return(new KeyPair(publicKey, privateKey));
}
var originalLocale = Platform.GetLocale();
try
{
// Force to english for known bug in date parsing:
// https://issuetracker.google.com/issues/37095309
Platform.SetLocale(Java.Util.Locale.English);
// Otherwise we create a new key
var generator = KeyPairGenerator.GetInstance(KeyProperties.KeyAlgorithmRsa, androidKeyStore);
var end = DateTime.UtcNow.AddYears(20);
var startDate = new Java.Util.Date();
#pragma warning disable CS0618 // Type or member is obsolete
var endDate = new Java.Util.Date(end.Year, end.Month, end.Day);
#pragma warning restore CS0618 // Type or member is obsolete
#pragma warning disable CS0618
var builder = new KeyPairGeneratorSpec.Builder(Platform.AppContext)
.SetAlias(asymmetricAlias)
.SetSerialNumber(Java.Math.BigInteger.One)
.SetSubject(new Javax.Security.Auth.X500.X500Principal($"CN={asymmetricAlias} CA Certificate"))
.SetStartDate(startDate)
.SetEndDate(endDate);
generator.Initialize(builder.Build());
#pragma warning restore CS0618
return(generator.GenerateKeyPair());
}
finally
{
Platform.SetLocale(originalLocale);
}
}