Clarify the documentation on the use of ChaCha20
@@ -21,7 +21,15 @@ The ChaCha20 stream cipher for EVP.
=item EVP_chacha20()
-The ChaCha20 stream cipher. The key length is 256 bits, the IV is 96 bits long.
+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
+bit nonce. For example a nonce of:
+
+000000000000000000000002
+
+With an initial counter of 42 (2a in hex) would be expressed as:
+
+2a000000000000000000000000000002
=item EVP_chacha20_poly1305()
