Having trouble decrypting in C# something encrypted on iPhone using RSA

Question

I\'ve spent two days on this so far and combed through every source at my disposal, so this is the last resort.

I have an X509 certificate whose public key I have stored

Answer 1

I believe you've answered the question yourself. The problem most certainly lies within the endianness.

This is a possible way of writing two-way conversion methods:

short convert_short(short in)
{
 short out;
 char *p_in = (char *) ∈
 char *p_out = (char *) &out;
 p_out[0] = p_in[1];
 p_out[1] = p_in[0];  
 return out;
}

long convert_long(long in)
{
 long out;
 char *p_in = (char *) ∈
 char *p_out = (char *) &out;
 p_out[0] = p_in[3];
 p_out[1] = p_in[2];
 p_out[2] = p_in[1];
 p_out[3] = p_in[0];  
 return out;
} 

This might be a good resource for you (other than wikipedia): http://betterexplained.com/articles/understanding-big-and-little-endian-byte-order/