自定义openssl生成RSA密钥参数

Question

I want to generate a keypair with openssl, but I can't set parameters to generate my private/public key. I want pass an input parameter, for example a identifier (example mac address), to obtain an unique private/public key. For the same identifier I want the same private/public key. How I can make this? Thanks in advance :D

Answer 1

RSA key pairs have to be generated randomly.

Making the generation deterministically - you no longer generate a key but derive the key from certain data (eg based on a MAC address). This reduces the security of the generated keys to zero - hence they are useless and you don't even have to start to generate them.

The central assumption the security of RSA bases on is that the private key is only known to the key owner. If you take a public information like the MAC address the following formula applies:

RSA key pair = your-derivation-algorithm( MAC address )

If you want to know the RSA private key (which is part of the key pair) you need the MAC address and the derivation-algorithm. The MAC is public and the derivation-algorithm will be public earlier or later.

Hence the RSA private key is public too, which makes it useless from a security perspective because everybody who knows the MAC address can generate it.

Keep in mind: Security bases on secret data in combination with a well-engineered algorithm. Whether the algorithm is public or not should not have any effect on the security. If it has an effect you have an insecure algorithm you can throw away.