[dev-crypto-csharp] PROBLEM CONVERTING FROM RSA PUBLIC KEYS FROM PKCS#1 TO SPKI FORMAT IN C#

[Vijay Tenneti]

Please can anyone help me convert RSA public keys (they are either RSA OAEP 
SHA256 keys for encryption / decryption or RSA SSA PKCS1 v1.5 with SHA256 
hashes for signing / verifying). iOS spits out keys in PKCS#1 format and 
WebCrypto on web browsers uses SPKI. I need interoperability between the two 
platforms, and am attempting to use Bouncy Castle in C# on the server (web api) 
to convert between the two formats.

Have been looking on the internet especially stack overflow and I can 
successfully convert from SPKI to PKCS1, thus:

        public static byte[] TranslateKeyInSpkiDERFormatToPKCS1(byte[] 
keyInSpkiFormat)
        {
            SubjectPublicKeyInfo spkiInfo = 
SubjectPublicKeyInfo.GetInstance((Asn1Sequence) 
Asn1Object.FromByteArray(keyInSpkiFormat));
            byte[] keyInPKCS1Format = spkiInfo.GetPublicKey().GetDerEncoded();

            return keyInPKCS1Format;
        }

Have been struggling to write a method that does the reverse - that converts 
PKCS#1 to SPKI - I wonder if someone has done something similar.

Thanks very much