如何从先前生成的ecdsa两个编码密钥对中构造私钥?

生成了这样的私钥:

    fun getKeyPair(): Pair<ByteArray, ByteArray> {
        Security.addProvider(provider)
        val generator = KeyPairGenerator.getInstance("ECDSA")
        val ecSpec = ECNamedCurveTable.getParameterSpec("secp256r1")
        generator.initialize(ecSpec)
        val keyPair = generator.generateKeyPair()
        val publicKey = keyPair.public as ECPublicKey
        val privateKey = keyPair.private
        return Pair(publicKey.q.getEncoded(true), privateKey.getEncoded())
    }

公钥可以像这样重新构建:

    Security.addProvider(...spongy castle provider)
    val ecSpecs = ECNamedCurveTable.getParameterSpec("secp256r1")
    val q = ecSpecs.curve.decodePoint(publicKeyEncoded)
    val pubSpec = ECPublicKeySpec(q, ecSpecs)
    val keyFactory = KeyFactory.getInstance("ECDSA")
    val generatedPublic = keyFactory.generatePublic(pubSpec)

如何能够同时从字节重建私钥?

更新:

这段代码在实际的应用程序中运行良好,但在JUnit测试中不起作用:

val keyFactory = KeyFactory.getInstance("ECDSA")
val privSpec = PKCS8EncodedKeySpec(privateEncoded)
val generatedPrivate = keyFactory.generatePrivate(privSpec)

在junit测试中,我得到这个错误:

java.security.spec.InvalidKeySpecException: encoded key spec not recognised

我的私钥编码字节有150字节大小。