The number of rounds is 12, 14, or 16, depending on the key size.
The actual key size can be anywhere from 8 to 2048 bits.
See key size for a discussion of this and other lengths.
According to the authors, the approach can be used on any cipher with key size up to 64-bits.
The full 16 rounds are used when the key size is longer than 80 bits.
In other words, the message expansion factor is equal to the public key size.
Progress in this challenge should give an insight into which key sizes are still safe and for how long.
The algorithm uses a key size of 128, 192, or 256 bits.
The influence of key size is shown in Fig. 7.16.
We see that the key size is most likely five.