The System.Security.Cryptography namespace contains several commonly used cryptographic algorithms. I propose the addition of two commonly used algorithms which are currently missing:

• Ed25519 is an implementation of an Edwards-curve Digital Signature Algorithm.
• Curve25519 is an algorithm designed to be used with elliptic curve Diffie-Hellman (ECDH) key exchange algorithm.

Both are based on the same elliptic curve. Many open source projects (e.g. OpenSSH, OpenBSD) seem to prefer this elliptic curve for use in elliptic curve cryptography (ECC). It is therefore beneficial to have these algorithms implemented in CoreFX.

The two algorithms should be included in the existing classes in the System.Security.Cryptography namespace, but it must be possible to explicitly ask for the usage of these algorithms.