PHP RSA public encrypt not matching C# encrypt

I Am trying to replicate the RSA public key encryption a C# project is using with PHP

I am using this code using C# and a public key.

public static RSACryptoServiceProvider DecodeX509PublicKey(byte[] x509key)
{
    byte[] SeqOID = { 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01 };

    MemoryStream ms = new MemoryStream(x509key);
    BinaryReader reader = new BinaryReader(ms);

    if (reader.ReadByte() == 0x30)
        ReadASNLength(reader); //skip the size
    else
        return null;

    int identifierSize = 0; //total length of Object Identifier section
    if (reader.ReadByte() == 0x30)
        identifierSize = ReadASNLength(reader);
    else
        return null;

    if (reader.ReadByte() == 0x06) //is the next element an object identifier?
    {
        int oidLength = ReadASNLength(reader);
        byte[] oidBytes = new byte[oidLength];
        reader.Read(oidBytes, 0, oidBytes.Length);
        if (oidBytes.SequenceEqual(SeqOID) == false) //is the object identifier rsaEncryption PKCS#1?
            return null;

        int remainingBytes = identifierSize - 2 - oidBytes.Length;
        reader.ReadBytes(remainingBytes);
    }

    if (reader.ReadByte() == 0x03) //is the next element a bit string?
    {
        ReadASNLength(reader); //skip the size
        reader.ReadByte(); //skip unused bits indicator
        if (reader.ReadByte() == 0x30)
        {
            ReadASNLength(reader); //skip the size
            if (reader.ReadByte() == 0x02) //is it an integer?
            {
                int modulusSize = ReadASNLength(reader);
                byte[] modulus = new byte[modulusSize];
                reader.Read(modulus, 0, modulus.Length);
                if (modulus[0] == 0x00) //strip off the first byte if it's 0
                {
                    byte[] tempModulus = new byte[modulus.Length - 1];
                    Array.Copy(modulus, 1, tempModulus, 0, modulus.Length - 1);
                    modulus = tempModulus;
                }

                if (reader.ReadByte() == 0x02) //is it an integer?
                {
                    int exponentSize = ReadASNLength(reader);
                    byte[] exponent = new byte[exponentSize];
                    reader.Read(exponent, 0, exponent.Length);

                    RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
                    RSAParameters RSAKeyInfo = new RSAParameters();
                    RSAKeyInfo.Modulus = modulus;
                    RSAKeyInfo.Exponent = exponent;
                    RSA.ImportParameters(RSAKeyInfo);
                    return RSA;
                }
            }
        }
    }
    return null;
}

public static int ReadASNLength(BinaryReader reader)
{
    //Note: this method only reads lengths up to 4 bytes long as
    //this is satisfactory for the majority of situations.
    int length = reader.ReadByte();
    if ((length & 0x00000080) == 0x00000080) //is the length greater than 1 byte
    {
        int count = length & 0x0000000f;
        byte[] lengthBytes = new byte[4];
        reader.Read(lengthBytes, 4 - count, count);
        Array.Reverse(lengthBytes); //
        length = BitConverter.ToInt32(lengthBytes, 0);
    }
    return length;
}

When using the same certificate and open_ssl with PHP I always get different results. I know that the c# solution is working, since it is capable to connect with the service (mc server) that my PHP script fails to connect to.

I narrowed it down to the php RSA encryption not giving the right output.

This is the php code I am currently using for the encryption:

$key = openssl_pkey_get_public( $cert);
openssl_public_encrypt("asdf",$result,$key, OPENSSL_PKCS1_PADDING);
echo base64_encode($result);

And here is an example of a public key (PEM):

-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC+1KNonOhZVYIKYhDyYh1rEGEMSq6gXT8PIpWs1AmEHowW6upSBMmwCvuwCCiA+rdcJue7FyLYDx7qvKAomDKzX4lKK7T5M7LU2el34nCYzMmiidp6cZ9IxIqvCNpJMIlPXuCXpVg1RtZxyWU7p0/PMQWSANy9JkDsGUuoGqnBIwIDAQAB
-----END PUBLIC KEY-----

I am trying to encrypt "asdf" with this key.

The c# code (which should be right since its being accepted by the server) is giving me this as a result

var test = RSAService.Encrypt(Encoding.UTF8.GetBytes("asdf"), false);
ConsoleIO.WriteLine(Convert.ToBase64String(dataTypes.GetArray(test)));

gAEqOSvVyTcqFxPPYB84EOE9nm4NFfu3rWihZStgAMlE4pPkT0ugeYWtiswSxSx48zlfqoaMh15nes0osRs4yGwhjv+FqqV12/FccpdWCMKp1WVluhDvOUmgI7v8a/YGOGCk6tyuPGcWiv0XawcFdvqwkCEBTc2Z2FI9nkAS9M6swg==

while PHP (using the code I posted above) is giving me

UpRBZX8mGr9NhY7l7VZYjFe3jFwJjEnGfx750cBEI4G0E+c6guKMlPLk9IM82nqjj9H62ohd2nN5Rs8iay1rchLLaVxSOdPnqaxb7t6VJ6jiwpwSTvfODd2Cafw3bzAEbCNIcl6t8LlekdYyx3onEIBLbWGGe/clxJMDqAXlr84=

Every help is appreciated, thank you very much!