private static bool TryDecrypt(
SafeRsaHandle key,
ReadOnlySpan <byte> data,
Span <byte> destination,
Interop.Crypto.RsaPadding rsaPadding,
RsaPaddingProcessor rsaPaddingProcessor,
out int bytesWritten)
{
// If rsaPadding is PKCS1 or OAEP-SHA1 then no depadding method should be present.
// If rsaPadding is NoPadding then a depadding method should be present.
Debug.Assert(
(rsaPadding == Interop.Crypto.RsaPadding.NoPadding) ==
(rsaPaddingProcessor != null));
// Caller should have already checked this.
Debug.Assert(!key.IsInvalid);
int rsaSize = Interop.Crypto.RsaSize(key);
if (destination.Length < rsaSize)
{
bytesWritten = 0;
return(false);
}
Span <byte> decryptBuf = destination;
byte[] paddingBuf = null;
if (rsaPaddingProcessor != null)
{
paddingBuf = ArrayPool <byte> .Shared.Rent(rsaSize);
decryptBuf = paddingBuf;
}
try
{
int returnValue = Interop.Crypto.RsaPrivateDecrypt(data.Length, data, decryptBuf, key, rsaPadding);
CheckReturn(returnValue);
if (rsaPaddingProcessor != null)
{
return(rsaPaddingProcessor.DepadOaep(paddingBuf, destination, out bytesWritten));
}
else
{
// If the padding mode is RSA_NO_PADDING then the size of the decrypted block
// will be RSA_size. If any padding was used, then some amount (determined by the padding algorithm)
// will have been reduced, and only returnValue bytes were part of the decrypted
// body. Either way, we can just use returnValue, but some additional bytes may have been overwritten
// in the destination span.
bytesWritten = returnValue;
}
return(true);
}
finally
{
if (paddingBuf != null)
{
// DecryptBuf is paddingBuf if paddingBuf is not null, erase it before returning it.
// If paddingBuf IS null then decryptBuf was destination, and shouldn't be cleared.
CryptographicOperations.ZeroMemory(decryptBuf);
ArrayPool <byte> .Shared.Return(paddingBuf);
}
}
}
private bool TrySignHash(
ReadOnlySpan <byte> hash,
Span <byte> destination,
HashAlgorithmName hashAlgorithm,
RSASignaturePadding padding,
bool allocateSignature,
out int bytesWritten,
out byte[] signature)
{
Debug.Assert(!string.IsNullOrEmpty(hashAlgorithm.Name));
Debug.Assert(padding != null);
signature = null;
// Do not factor out getting _key.Value, since the key creation should not happen on
// invalid padding modes.
if (padding.Mode == RSASignaturePaddingMode.Pkcs1)
{
int algorithmNid = GetAlgorithmNid(hashAlgorithm);
SafeRsaHandle rsa = _key.Value;
int bytesRequired = Interop.Crypto.RsaSize(rsa);
if (allocateSignature)
{
Debug.Assert(destination.Length == 0);
signature = new byte[bytesRequired];
destination = signature;
}
if (destination.Length < bytesRequired)
{
bytesWritten = 0;
return(false);
}
if (!Interop.Crypto.RsaSign(algorithmNid, hash, hash.Length, destination, out int signatureSize, rsa))
{
throw Interop.Crypto.CreateOpenSslCryptographicException();
}
Debug.Assert(
signatureSize == bytesRequired,
$"RSA_sign reported signatureSize was {signatureSize}, when {bytesRequired} was expected");
bytesWritten = signatureSize;
return(true);
}
else if (padding.Mode == RSASignaturePaddingMode.Pss)
{
RsaPaddingProcessor processor = RsaPaddingProcessor.OpenProcessor(hashAlgorithm);
SafeRsaHandle rsa = _key.Value;
int bytesRequired = Interop.Crypto.RsaSize(rsa);
if (allocateSignature)
{
Debug.Assert(destination.Length == 0);
signature = new byte[bytesRequired];
destination = signature;
}
if (destination.Length < bytesRequired)
{
bytesWritten = 0;
return(false);
}
byte[] pssRented = ArrayPool <byte> .Shared.Rent(bytesRequired);
Span <byte> pssBytes = new Span <byte>(pssRented, 0, bytesRequired);
processor.EncodePss(hash, pssBytes, KeySize);
int ret = Interop.Crypto.RsaSignPrimitive(pssBytes, destination, rsa);
pssBytes.Clear();
ArrayPool <byte> .Shared.Return(pssRented);
CheckReturn(ret);
Debug.Assert(
ret == bytesRequired,
$"RSA_private_encrypt returned {ret} when {bytesRequired} was expected");
bytesWritten = ret;
return(true);
}
throw PaddingModeNotSupported();
}
internal RSAAndroid(SafeRsaHandle key)
{
_key = new Lazy <SafeRsaHandle>(key.DuplicateHandle());
SetKeySizeFromHandle(key);
}
public override bool TryDecrypt(
ReadOnlySpan <byte> data,
Span <byte> destination,
RSAEncryptionPadding padding,
out int bytesWritten)
{
if (padding == null)
{
throw new ArgumentNullException(nameof(padding));
}
Interop.Crypto.RsaPadding rsaPadding = GetInteropPadding(padding, out RsaPaddingProcessor? oaepProcessor);
SafeRsaHandle key = GetKey();
int keySizeBytes = Interop.Crypto.RsaSize(key);
// OpenSSL does not take a length value for the destination, so it can write out of bounds.
// To prevent the OOB write, decrypt into a temporary buffer.
if (destination.Length < keySizeBytes)
{
Span <byte> tmp = stackalloc byte[0];
byte[]? rent = null;
// RSA up through 4096 stackalloc
if (keySizeBytes <= 512)
{
tmp = stackalloc byte[keySizeBytes];
}
else
{
rent = ArrayPool <byte> .Shared.Rent(keySizeBytes);
tmp = rent;
}
bool ret = TryDecrypt(key, data, tmp, rsaPadding, oaepProcessor, out bytesWritten);
if (ret)
{
tmp = tmp.Slice(0, bytesWritten);
if (bytesWritten > destination.Length)
{
ret = false;
bytesWritten = 0;
}
else
{
tmp.CopyTo(destination);
}
CryptographicOperations.ZeroMemory(tmp);
}
if (rent != null)
{
// Already cleared
ArrayPool <byte> .Shared.Return(rent);
}
return(ret);
}
return(TryDecrypt(key, data, destination, rsaPadding, oaepProcessor, out bytesWritten));
}
public override void ImportParameters(RSAParameters parameters)
{
ValidateParameters(ref parameters);
ThrowIfDisposed();
if (parameters.Exponent == null || parameters.Modulus == null)
{
throw new CryptographicException(SR.Cryptography_InvalidRsaParameters);
}
// Check that either all parameters are not null or all are null, if a subset were set, then the parameters are invalid.
// If the parameters are all not null, verify the integrity of their lengths.
if (parameters.D == null)
{
if (parameters.P != null ||
parameters.DP != null ||
parameters.Q != null ||
parameters.DQ != null ||
parameters.InverseQ != null)
{
throw new CryptographicException(SR.Cryptography_InvalidRsaParameters);
}
}
else
{
if (parameters.P == null ||
parameters.DP == null ||
parameters.Q == null ||
parameters.DQ == null ||
parameters.InverseQ == null)
{
throw new CryptographicException(SR.Cryptography_InvalidRsaParameters);
}
// Half, rounded up.
int halfModulusLength = (parameters.Modulus.Length + 1) / 2;
// Matching the .NET Framework RSACryptoServiceProvider behavior, as that's the .NET de facto standard
if (parameters.D.Length != parameters.Modulus.Length ||
parameters.P.Length != halfModulusLength ||
parameters.Q.Length != halfModulusLength ||
parameters.DP.Length != halfModulusLength ||
parameters.DQ.Length != halfModulusLength ||
parameters.InverseQ.Length != halfModulusLength)
{
throw new CryptographicException(SR.Cryptography_InvalidRsaParameters);
}
}
SafeRsaHandle key = Interop.AndroidCrypto.RsaCreate();
bool imported = false;
if (key is null || key.IsInvalid)
{
throw new CryptographicException();
}
try
{
if (!Interop.AndroidCrypto.SetRsaParameters(
key,
parameters.Modulus,
parameters.Modulus != null ? parameters.Modulus.Length : 0,
parameters.Exponent,
parameters.Exponent != null ? parameters.Exponent.Length : 0,
parameters.D,
parameters.D != null ? parameters.D.Length : 0,
parameters.P,
parameters.P != null ? parameters.P.Length : 0,
parameters.DP,
parameters.DP != null ? parameters.DP.Length : 0,
parameters.Q,
parameters.Q != null ? parameters.Q.Length : 0,
parameters.DQ,
parameters.DQ != null ? parameters.DQ.Length : 0,
parameters.InverseQ,
parameters.InverseQ != null ? parameters.InverseQ.Length : 0))
{
throw new CryptographicException();
}
imported = true;
}
finally
{
if (!imported)
{
key.Dispose();
}
}
FreeKey();
_key = new Lazy <SafeRsaHandle>(key);
SetKeySizeFromHandle(key);
}
public override bool VerifyHash(ReadOnlySpan <byte> hash, ReadOnlySpan <byte> signature, HashAlgorithmName hashAlgorithm, RSASignaturePadding padding)
{
if (string.IsNullOrEmpty(hashAlgorithm.Name))
{
throw HashAlgorithmNameNullOrEmpty();
}
if (padding == null)
{
throw new ArgumentNullException(nameof(padding));
}
if (padding != RSASignaturePadding.Pkcs1 && padding != RSASignaturePadding.Pss)
{
throw PaddingModeNotSupported();
}
RsaPaddingProcessor processor = RsaPaddingProcessor.OpenProcessor(hashAlgorithm);
SafeRsaHandle rsa = GetKey();
int requiredBytes = Interop.AndroidCrypto.RsaSize(rsa);
if (signature.Length != requiredBytes)
{
return(false);
}
if (hash.Length != processor.HashLength)
{
return(false);
}
byte[] rented = CryptoPool.Rent(requiredBytes);
Span <byte> unwrapped = new Span <byte>(rented, 0, requiredBytes);
try
{
int ret = Interop.AndroidCrypto.RsaVerificationPrimitive(signature, unwrapped, rsa);
CheckReturn(ret);
if (ret == 0)
{
// Return value of 0 from RsaVerificationPrimitive indicates the signature could not be decrypted.
return(false);
}
Debug.Assert(
ret == requiredBytes,
$"RsaVerificationPrimitive returned {ret} when {requiredBytes} was expected");
if (padding == RSASignaturePadding.Pkcs1)
{
byte[] repadRent = CryptoPool.Rent(unwrapped.Length);
Span <byte> repadded = repadRent.AsSpan(0, requiredBytes);
processor.PadPkcs1Signature(hash, repadded);
bool valid = CryptographicOperations.FixedTimeEquals(repadded, unwrapped);
CryptoPool.Return(repadRent, requiredBytes);
return(valid);
}
else if (padding == RSASignaturePadding.Pss)
{
return(processor.VerifyPss(hash, unwrapped, KeySize));
}
else
{
Debug.Fail("Padding mode should be checked prior to this point.");
throw PaddingModeNotSupported();
}
}
finally
{
CryptoPool.Return(rented, requiredBytes);
}
throw PaddingModeNotSupported();
}
private bool TrySignHash(
ReadOnlySpan <byte> hash,
Span <byte> destination,
HashAlgorithmName hashAlgorithm,
RSASignaturePadding padding,
bool allocateSignature,
out int bytesWritten,
out byte[]?signature)
{
Debug.Assert(!string.IsNullOrEmpty(hashAlgorithm.Name));
Debug.Assert(padding != null);
signature = null;
if (padding != RSASignaturePadding.Pkcs1 && padding != RSASignaturePadding.Pss)
{
throw PaddingModeNotSupported();
}
RsaPaddingProcessor processor = RsaPaddingProcessor.OpenProcessor(hashAlgorithm);
SafeRsaHandle rsa = GetKey();
int bytesRequired = Interop.AndroidCrypto.RsaSize(rsa);
if (allocateSignature)
{
Debug.Assert(destination.Length == 0);
signature = new byte[bytesRequired];
destination = signature;
}
if (destination.Length < bytesRequired)
{
bytesWritten = 0;
return(false);
}
byte[] encodedRented = CryptoPool.Rent(bytesRequired);
Span <byte> encodedBytes = new Span <byte>(encodedRented, 0, bytesRequired);
if (padding.Mode == RSASignaturePaddingMode.Pkcs1)
{
processor.PadPkcs1Signature(hash, encodedBytes);
}
else if (padding.Mode == RSASignaturePaddingMode.Pss)
{
processor.EncodePss(hash, encodedBytes, KeySize);
}
else
{
Debug.Fail("Padding mode should be checked prior to this point.");
throw PaddingModeNotSupported();
}
int ret = Interop.AndroidCrypto.RsaSignPrimitive(encodedBytes, destination, rsa);
CryptoPool.Return(encodedRented, bytesRequired);
CheckReturn(ret);
Debug.Assert(
ret == bytesRequired,
$"RsaSignPrimitive returned {ret} when {bytesRequired} was expected");
bytesWritten = ret;
return(true);
}