可以使用下面的代码创建这样的键

func createPrivateKey() {
    let attributes = [
        kSecAttrKeyType: kSecAttrKeyTypeECSECPrimeRandom,
        kSecAttrKeyClass: kSecAttrKeyClassPrivate,
        kSecAttrKeySizeInBits: 256,
        kSecAttrIsPermanent: false
    ] as [CFString: Any]
    
    var error: Unmanaged<CFError>?
    let privateKey = SecKeyCreateRandomKey(attributes as CFDictionary, &error)
    print(privateKey ?? error!.takeUnretainedValue())
}

此SecKey中的密码有效，可以使用它们重新创建具有功能的P256密钥

try P256.Signing.PrivateKey(rawRepresentation: "PRIVATE_KEY_DATA")