bip324: fix link to chacha20

Author: stratospher

bip-0324.mediawiki

@@ -396,7 +396,7 @@ Packet encryption is built on two existing primitives:
 * '''ChaCha20Poly1305''' is specified as <code>AEAD_CHACHA20_POLY1305</code> in [https://datatracker.ietf.org/doc/html/rfc8439#section-2.8 RFC 8439 section 2.8]. It is an authenticated encryption protocol with associated data (AEAD), taking a 256-bit key, 96-bit nonce, and an arbitrary-length byte array of associated authenticated data (AAD). Due to the built-in authentication tag, ciphertexts are 16 bytes longer than the corresponding plaintext. In what follows:
 ** <code>aead_chacha20_poly1305_encrypt(key, nonce, aad, plaintext)</code> refers to a function that takes as input a 32-byte array ''key'', a 12-byte array ''nonce'', an arbitrary-length byte array ''aad'', and an arbitrary-length byte array ''plaintext'', and returns a byte array ''ciphertext'', 16 bytes longer than the plaintext.
 ** <code>aead_chacha20_poly1305_decrypt(key, nonce, aad, ciphertext)</code> refers to a function that takes as input a 32-byte array ''key'', a 12-byte array ''nonce'', an arbitrary-length byte array ''aad'', and an arbitrary-length byte array ''ciphertext'', and returns either a byte array ''plaintext'' (16 bytes shorter than the ciphertext), or ''None'' in case the ciphertext was not a valid ChaCha20Poly1305 encryption of any plaintext with the specified ''key'', ''nonce'', and ''aad''.
-* The '''ChaCha20 Block Function''' is specified in [https://datatracker.ietf.org/doc/html/rfc8439#section-2.8 RFC 8439 section 2.3]. It is a pseudorandom function (PRF) taking a 256-bit key, 96-bit nonce, and 32-bit counter, and outputs 64 pseudorandom bytes. It is the underlying building block on which ChaCha20 (and ultimately, ChaCha20Poly1305) is built. In what follows:
+* The '''ChaCha20 Block Function''' is specified in [https://datatracker.ietf.org/doc/html/rfc8439#section-2.3 RFC 8439 section 2.3]. It is a pseudorandom function (PRF) taking a 256-bit key, 96-bit nonce, and 32-bit counter, and outputs 64 pseudorandom bytes. It is the underlying building block on which ChaCha20 (and ultimately, ChaCha20Poly1305) is built. In what follows:
 ** <code>chacha20_block(key, nonce, count)</code> refers to a function that takes as input a 32-byte array ''key'', a 12-byte array ''nonce'', and an integer ''count'' in range ''0..2<sup>32</sup>-1'', and returns a byte array of length 64.
 
 These will be used for plaintext encryption and length encryption, respectively.