A 1986 code-based encryption scheme that hid a Reed-Solomon code, broken in 1992.
The idea: Instead of encoding the message and adding errors (McEliece), Niederreiter turns the message into the error pattern itself and publishes a short summary of it (the syndrome). The owner, who can decode, recovers the errors and so the message. The weakness was the choice of code, not the construction.
Why it matters: Its construction survives in Classic McEliece, which hides a different kind of code.
On the map: ✗ proposed 1986
Harald Niederreiter's 1986 code-based encryption, the "dual" form of McEliece: the message is encoded as the error pattern itself, and the ciphertext is its syndrome. It is as secure as McEliece for the same code[1] and gives shorter ciphertexts.
The construction lives on: Classic McEliece is built in Niederreiter form[2], with binary Goppa codes. The Reed-Solomon version was broken in 1992.
If any of these breaks, this breaks too.
If this breaks, these break with it.
Nothing on the map depends on it: it is an end point, something people use directly.