Chacha20poly1305.xkey: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/src/crypto/aead/chacha20poly1305.bend as Chacha20poly1305
Lines 69-72 of bend-collections@1.0.0.0/src/crypto/aead/chacha20poly1305.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/src/crypto/aead/chacha20poly1305.bend&start_line=69&end_line=72

import Base
import bend-collections@1.0.0.0/src/crypto/chacha/chacha20.bend as CH

# XChaCha20-Poly1305: the HChaCha20 subkey of nonce[0..16] and the nonce
# 0x00000000 || nonce[16..24].
def xkey(key: List<&2, U32>, nonce: List<&2, U32>) -> List<&2, U32>:
  CH.hchacha20_unchecked(key, CH.take(16n, nonce))

Uses (4):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/chacha/chacha20.bend&name=hchacha20_unchecked
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/crypto/chacha/chacha20.bend&name=take