Well you had to have that sort of protection in "piracy" ridden devices such as gaming consoles and STBs. CableCard, Ugh I dont even wanna get into that. RSA/3DES/IDEA. One time a TV programming service used to run ECC post-processing on 56-bit DES odd/even control words, AFTER using a RSA/IDEA/RSA MECM decryption mechanism, ECC = Elliptic Curve Cryptography.
Oh, those control-words would rotate every 8 to 15 seconds with a brand new algorithm with each MECM transmission. This still happens today. Except now, the whole process is wrapped in an MDC2 signature checking to verify MECM authenticity prior to decryption, the unwrapped result contains the keyselect to know which IDEA key to pull. Once its pulled, it undergoes an expansion process that gives you P and Q to build the 1024bit RSA keys. and on and on and on and on... ill stop here. lol.
And the most amazing part about all of this, This all happens on an 8-bit 6805 based core!
But I digress.....
Oh, those control-words would rotate every 8 to 15 seconds with a brand new algorithm with each MECM transmission. This still happens today. Except now, the whole process is wrapped in an MDC2 signature checking to verify MECM authenticity prior to decryption, the unwrapped result contains the keyselect to know which IDEA key to pull. Once its pulled, it undergoes an expansion process that gives you P and Q to build the 1024bit RSA keys. and on and on and on and on... ill stop here. lol.
And the most amazing part about all of this, This all happens on an 8-bit 6805 based core!
But I digress.....