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

Errata ID: 5989
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Lê Minh Đăng
Date Reported: 2020-02-26
Verifier Name: Stanislav Smyshlyaev
Date Verified: 2021-04-28

Section 2.4.1 says:

encrypted_message +=  block ^ key_stream
...
encrypted_message += (block^key_stream)[0..len(plaintext)%64]

It should say:

encrypted_message |= block ^ key_stream
...
encrypted_message |= (block^key_stream)[0..len(plaintext)%64]

Notes:

The encrypted_message is the result of concatenation of blocks.
"|" and "|=" are used for concatenation elsewhere in the document, changing "+=" to "|=" will reduce ambiguity.

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