RFC 8439, "ChaCha20 and Poly1305 for IETF Protocols", June 2018

Errata ID: 5689
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Stefan Heiss
Date Reported: 2019-04-11
Verifier Name: Colin Perkins
Date Verified: 2019-04-15

Section 2.5.1 says:

for i=1 upto ceil(msg length in bytes / 16)
   n = le_bytes_to_num(msg[((i-1)*16)..(i*16)] | [0x01])
   a += n
   a = (r * a) % p
   end

It should say:

for i=1 upto ceil(msg length in bytes / 16)
   j = min(i*16-1, msg length in bytes - 1)
   n = le_bytes_to_num(msg[((i-1)*16)..j] | [0x01])
   a += n
   a = (r * a) % p
   end

Notes:

Correction of Errata 5675

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