=item EVP_chacha20()
The ChaCha20 stream cipher. The key length is 256 bits, the IV is 128 bits long.
-The first 32 bits consists of a counter in little-endian order followed by a 96
+The first 64 bits consists of a counter in little-endian order followed by a 64
bit nonce. For example a nonce of:
-000000000000000000000002
+0000000000000002
With an initial counter of 42 (2a in hex) would be expressed as:
L<EVP_CIPHER_fetch(3)> instead.
See L<crypto(7)/Performance> for further information.
+L<RFC 7539|https://www.rfc-editor.org/rfc/rfc7539.html#section-2.4>
+uses a 32 bit counter and a 96 bit nonce for the IV.
+
=head1 RETURN VALUES
These functions return an B<EVP_CIPHER> structure that contains the