ED25519

• Ed25519 is an EdDSA signature scheme that uses Edwards curve equivalent of Curve25519 for digital signatures.
• The “25519” in Ed25519 and Curve25519 refers to the prime number ($2^{255}-19$), which is a fundamental part of the curve’s definition. Ed25519 uses 256-bit private keys and produces 256-bit public keys.
  • therefore, cryptographic-length of Ed25519 is 256 bits, i.e. $2^{256}$ of possible private keys.