Illegal base64 letter at input byte 4

[GuilhermeStrice]

What i want to do is pretty simple

var keys = await RSA.generate(2048);
_ourPrivateKey = keys.privateKey;
_ourPublicKey = keys.publicKey;

// Application 1
var enc = await RSA.encryptOAEP(message, "yes", Hash.SHA256, _ourPublicKey);

// at this point the message has arrived on Application 2
var dec = await RSA.decryptOAEP(message, "yes", Hash.SHA256, _ourPrivateKey);

But it throws RSAException - Illegal base64 letter at input byte 4

The public keys being negotiated between the applications are correct