/// <summary>
/// Creates a new ECDsaAndroid object that will use a randomly generated key of the specified size.
/// </summary>
/// <param name="keySize">Size of the key to generate, in bits.</param>
public ECDsaAndroid(int keySize)
{
// Use the base setter to get the validation and field assignment without the
// side effect of dereferencing _key.
base.KeySize = keySize;
_key = new ECAndroid(this);
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
_key?.Dispose();
_key = null !;
}
base.Dispose(disposing);
}
internal ECDiffieHellmanAndroidPublicKey(SafeEcKeyHandle ecKeyHandle)
{
ArgumentNullException.ThrowIfNull(ecKeyHandle);
if (ecKeyHandle.IsInvalid)
{
throw new ArgumentException(SR.Cryptography_OpenInvalidHandle, nameof(ecKeyHandle));
}
_key = new ECAndroid(ecKeyHandle.DuplicateHandle());
}
public override ECParameters ExportParameters() => ECAndroid.ExportParameters(GetKey(), includePrivateParameters: false);
internal ECDiffieHellmanAndroidPublicKey(ECParameters parameters)
{
_key = new ECAndroid(parameters);
}
public override ECParameters ExportParameters(bool includePrivateParameters)
{
ThrowIfDisposed();
return(ECAndroid.ExportParameters(_key.Value, includePrivateParameters));
}
internal ECDsaAndroid(SafeEcKeyHandle ecKeyHandle)
{
_key = new ECAndroid(ecKeyHandle.DuplicateHandle());
ForceSetKeySize(_key.KeySize);
}
/// <summary>
/// Create an ECDsaAndroid algorithm with a named curve.
/// </summary>
/// <param name="curve">The <see cref="ECCurve"/> representing the curve.</param>
/// <exception cref="ArgumentNullException">if <paramref name="curve" /> is null.</exception>
public ECDsaAndroid(ECCurve curve)
{
_key = new ECAndroid(curve);
ForceSetKeySize(_key.KeySize);
}
public override ECParameters ExportParameters(bool includePrivateParameters) => ECAndroid.ExportParameters(GetKey(), includePrivateParameters);
public ECDiffieHellmanAndroid(int keySize)
{
base.KeySize = keySize;
_key = new ECAndroid(this);
}
public ECDiffieHellmanAndroid(ECCurve curve)
{
_key = new ECAndroid(curve);
KeySizeValue = _key.KeySize;
}
/// <summary>
/// Get the secret agreement generated between two parties
/// </summary>
private byte[]? DeriveSecretAgreement(ECDiffieHellmanPublicKey otherPartyPublicKey, IncrementalHash?hasher)
{
Debug.Assert(otherPartyPublicKey != null);
// Ensure that this ECDH object contains a private key by attempting a parameter export
// which will throw an OpenSslCryptoException if no private key is available
ECParameters thisKeyExplicit = ExportExplicitParameters(true);
bool thisIsNamed = Interop.AndroidCrypto.EcKeyHasCurveName(_key.Value);
ECDiffieHellmanAndroidPublicKey?otherKey = otherPartyPublicKey as ECDiffieHellmanAndroidPublicKey;
bool disposeOtherKey = false;
if (otherKey == null)
{
disposeOtherKey = true;
ECParameters otherParameters =
thisIsNamed
? otherPartyPublicKey.ExportParameters()
: otherPartyPublicKey.ExportExplicitParameters();
otherKey = new ECDiffieHellmanAndroidPublicKey(otherParameters);
}
bool otherIsNamed = otherKey.HasCurveName;
SafeEcKeyHandle?ourKey = null;
SafeEcKeyHandle?theirKey = null;
byte[]? rented = null;
// Calculate secretLength in bytes.
int secretLength = AsymmetricAlgorithmHelpers.BitsToBytes(KeySize);
try
{
if (otherKey.KeySize != KeySize)
{
throw new ArgumentException(SR.Cryptography_ArgECDHKeySizeMismatch, nameof(otherPartyPublicKey));
}
if (otherIsNamed == thisIsNamed)
{
ourKey = _key.UpRefKeyHandle();
theirKey = otherKey.DuplicateKeyHandle();
}
else if (otherIsNamed)
{
ourKey = _key.UpRefKeyHandle();
using (ECAndroid tmp = new ECAndroid(otherKey.ExportExplicitParameters()))
{
theirKey = tmp.UpRefKeyHandle();
}
}
else
{
using (ECAndroid tmp = new ECAndroid(thisKeyExplicit))
{
ourKey = tmp.UpRefKeyHandle();
}
theirKey = otherKey.DuplicateKeyHandle();
}
// Indicate that secret can hold stackallocs from nested scopes
Span <byte> secret = stackalloc byte[0];
// Arbitrary limit. But it covers secp521r1, which is the biggest common case.
const int StackAllocMax = 66;
if (secretLength > StackAllocMax)
{
rented = CryptoPool.Rent(secretLength);
secret = new Span <byte>(rented, 0, secretLength);
}
else
{
secret = stackalloc byte[secretLength];
}
if (!Interop.AndroidCrypto.EcdhDeriveKey(ourKey, theirKey, secret, out int usedBufferLength))
{
throw new CryptographicException();
}
Debug.Assert(secretLength == usedBufferLength, $"Expected secret length {secretLength} does not match actual secret length {usedBufferLength}.");
if (hasher == null)
{
return(secret.ToArray());
}
else
{
hasher.AppendData(secret);
return(null);
}
}
finally
{
theirKey?.Dispose();
ourKey?.Dispose();
if (disposeOtherKey)
{
otherKey.Dispose();
}
if (rented != null)
{
CryptoPool.Return(rented, secretLength);
}
}
}
internal ECDiffieHellmanAndroid(SafeEcKeyHandle ecKeyHandle)
{
_key = new ECAndroid(ecKeyHandle.DuplicateHandle());
KeySizeValue = _key.KeySize;
}
