# Key size for x25519

_Help · started by DeavmiDesktop on Sun, Nov 8, 2026 1:11 PM_

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## Original post

**DeavmiDesktop** · Sun, Nov 8, 2026 1:11 PM

I see that the specification mentions that the encryption is done via X25519 keys. These are using ECDH and specifically the curve 25519. I have a question though, as part of my Go implementation that I am writing, for pure fun and for learning fundementals. I noticed that the spcification mentions 512bits. Hopwever, `crypto/ecdh`, complains when one pushes in a key that is not exactly 32 bytes long. 32*8 = 256 bits, a shortfall of half the bytes.

Am I missing something then, because I feel somewhat dumb founded about this, unless I am reading the specification wrong:

>Asymmetric X25519 encryption and Ed25519 signatures as a basis for all communication

And then:

>The foundational Reticulum Identity Keys are 512-bit Elliptic Curve keysets

Any text-based explanatory help would be appreciated.

Regards,
TBVK

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