Corda - Crypto.doVerify never returns false

Question

I just found this code in Corda's crypto API for handling key verification:

fun doVerify(signatureScheme: SignatureScheme, publicKey: PublicKey, signatureData: ByteArray, clearData: ByteArray): Boolean {
    require(Crypto.isSupportedSignatureScheme(signatureScheme)) {
        "Unsupported key/algorithm for schemeCodeName: ${signatureScheme.schemeCodeName}"
    }
    if (signatureData.isEmpty()) throw IllegalArgumentException("Signature data is empty!")
    if (clearData.isEmpty()) throw IllegalArgumentException("Clear data is empty, nothing to verify!")
    val verificationResult = Crypto.isValid(signatureScheme, publicKey, signatureData, clearData)
    if (verificationResult) {
        return true
    } else {
        throw SignatureException("Signature Verification failed!")
    }
}

I can understand throwing exceptions when arguments are invalid, but I'm curious as to why this either returns true, or throws another exception when verificationResult is false, rather than just return verificationResult. This seems like a highly unusual design choice!

Could someone, ideally from the R3 engineering team explain?

Answer 1

No engineering team here, but I guess it is because Crypto.doVerify is the function called from TransactionSignature.verify, which is the one used in the flows to verify the signatures. Raising an exception in such an essential function, allows the flow to wrap it to a FlowException so that it can be managed by the Flow Hospital.