Enable skipped SSC.Algorithms tests on Andorid

DSAKeyGeneration.GenerateSecondMinKey and DSAKeyGeneration.GenerateMinKey no longer fail.  Added validation in RSAAndroid.cs to make RSAXml.FromNonsenseXml pass.

Fixes dotnet#50580
Fixes dotnet#50581

src/libraries/Common/src/System/Security/Cryptography/RSAAndroid.cs

@@ -381,6 +381,53 @@ public override void ImportParameters(RSAParameters parameters)
                 ValidateParameters(ref parameters);
                 ThrowIfDisposed();
 
+                if (parameters.Exponent == null || parameters.Modulus == null)
+                {
+                    throw new CryptographicException(SR.Cryptography_InvalidRsaParameters);
+                }
+
+                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;
+
+                    // The same checks are done by RSACryptoServiceProvider on import (when building the key blob)
+                    // Historically RSACng let CNG handle this (reporting NTE_NOT_SUPPORTED), but on RS1 CNG let the
+                    // import succeed, then on private key use (e.g. signing) it would report NTE_INVALID_PARAMETER.
+                    //
+                    // Doing the check here prevents the state in RS1 where the Import succeeds, but corrupts the key,
+                    // and makes for a friendlier exception message.
+                    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;
 

src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/DSA/DSAKeyGeneration.cs

@@ -24,14 +24,12 @@ public static void VerifyDefaultKeySize_Fips186_2()
         }
 
         [ConditionalFact(nameof(SupportsKeyGeneration))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/50580", TestPlatforms.Android)]
         public static void GenerateMinKey()
         {
             GenerateKey(dsa => GetMin(dsa.LegalKeySizes));
         }
 
         [ConditionalFact(nameof(SupportsKeyGeneration), nameof(HasSecondMinSize))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/50580", TestPlatforms.Android)]
         public static void GenerateSecondMinKey()
         {
             GenerateKey(dsa => GetSecondMin(dsa.LegalKeySizes));

src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/RSA/RSAXml.cs

@@ -1340,7 +1340,6 @@ public static void FromInvalidXml()
         }
 
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/29515", TestPlatforms.OSX | TestPlatforms.Android)]
         public static void FromNonsenseXml()
         {
             // This is DiminishedDPParameters XML, but with a P that is way too long.