Base64::toBase64 but no Base64::fromBase64?

I’m trying to write code to encrypt/decrypt strings in a cross-platform way, basically so a Python-based server can send encrypted messages which are decrypted in a JUCE-based plugin, by base-64 encoding those strings and then applying RSA-encryption. I am having trouble simply encoding a string into a MemoryBlock and getting the original string back out. It seems that everything would work if there was a corresponding Base64::fromBase64 function, but there isn’t. My code so far:

String original = "Hello I am Example Text.";
String base64String = Base64::toBase64(original);

MemoryOutputStream inputStream;
Base64::convertFromBase64(static_cast<OutputStream&>(inputStream), base64String);

//For later:
//applyRSA(inputStream.getMemoryBlock(), key)

MemoryOutputStream outputStream;
Base64::convertToBase64(outputStream, inputStream.getData(), inputStream.getDataSize());
String recovered = outputStream.toString()

The value of recovered is the same as base64String - is there a way to effectively reverse the Base64::toBase64 function and recover the original String?

Also open to suggestions if I’m way off-base - I thought this would be easier so maybe I’m on the wrong path.

For anybody who comes across this in the future, here is what ended up working:

const String original = "Hello I am Example Text";
//Use getNumBytesAsUTF8() to prevent trailing bytes
MemoryBlock inputBlock(original.toRawUTF8(), original.getNumBytesAsUTF8());
applyRSA(inputBlock, privateKey);

MemoryOutputStream inputBase64;
bool success = Base64::convertToBase64(
	static_cast<OutputStream&>(inputBase64),
	inputBlock.getData(), inputBlock.getSize());
const String encryptedString = String::createStringFromData(inputBase64.getData(),
	inputBase64.getDataSize());

MemoryOutputStream outputBase64;
success = Base64::convertFromBase64(
	static_cast<OutputStream&>(outputBase64), encryptedString);
MemoryBlock outputBlock(outputBase64.getMemoryBlock());
applyRSA(outputBlock, publicKey);
const String recoveredString = block2.toString();