XIP4003C from Xiphera is a very compact Intellectual Property (IP) core designed for efficient X25519 key exchange and Ed25519-based Edwards-curve Digital Signature Algorithm (EdDSA). XIP4003C implements arithmetic on Curve25519 , and provides a security level of 128 bits. Curve25519 is used in numerous contemporary security protocols and applications, including TLS 1.3.
XIP4003C has been designed for easy integration with FPGA- and ASIC-based designs in a vendor-agnostic design methodology, and the functionality of XIP4003C does not rely on any FPGA manufacturer-specific features.
XIP4003C supports the following operations:
The internal word width is set to 17 bits, as this leads to an efficient internal implementation  of the multiplication algorithm.
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Figure 1: Internal high-level block diagram of XIP4003C
 Curve25519 is formally defined as y² = x³ + 486662x² + x over the finite field defined by the prime number 2²⁵⁵ − 19.
 The exact number depends on the targeted FPGA architecture.
 15 · 17 bits = 255 bits.
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