I do not seem to understand how this challenge works.
In RSA you need the private key to decrypt anything that is encrypted by it by it. Now I don't know how it works with encryption, but when you're RSA/DSA/ECDSA signing something with the private key, the public key is exposed. But that doesn't really matter here because he also shared the public key by itself.
If something is "encrypted by the public key", that is by keypair and no password, right? Hopefully he did not use the public key as a pasword, because that would not make sense?
In RSA you need the private key to decrypt anything that is encrypted by it by it. Now I don't know how it works with encryption, but when you're RSA/DSA/ECDSA signing something with the private key, the public key is exposed. But that doesn't really matter here because he also shared the public key by itself.
If something is "encrypted by the public key", that is by keypair and no password, right? Hopefully he did not use the public key as a pasword, because that would not make sense?
Looks like more or less he is just making the point that he really can't decrypt anything.
If he can decrypt it, he would then have the private key and then could sign anything. So if he really did find out a way to to decrypt something without the private key somehow then he would have the private key.
But, since it can't be done its more or less a FU to him.
This is the same as the magic carburetor that allowed you to get 200 miles to a gallon of gas in your 2 ton truck, it just can't be done.
You just need to use uranium instead of gasoline.
-Dave