SHA-1 is considered broken. That's why I'm assuming that using SHA-1 for RFC2289 OTPs is broken as well. Is this assumption correct?
Going further with this assumption using SHA-1 for RFC4226 HOTPs should be broken too, is it? Although this blog states the following: "it doesn't affect applications such as HMAC where collisions aren't important". Does this also applies for HOTP?
A detailed explanation would be really appreciated.
Thank you very much in advance.