[mikehall314]

I agree 72 characters is plenty for most circumstances. However, as the blog points out, this is a byte limit not a character limit.

Some of the family emoji can be > 20 bytes. Some of the profession emoji can be > 17 bytes. If people are using emoji in their passwords, we could quite quickly run out of bytes.

I think it’s a limitation worth being aware of, even if “unsafe” is perhaps overstating it.

[byhemechi]

I still don't see how that's an issue, yes a password using a series of ridiculously complicated family emoji will be truncated but the actual bytes still provide entropy, just because the data doesn't use pixels when rendered doesn't mean it doesn't increase the search space

[anonym29]

If your password is comprised of three emojis that each take up 24 bytes, then yes, a 72 byte truncation dramatically reduces the search space for a brute force against these hypothetical 24-byte-emoji-only passwords.

There are far fewer possible combinations of any three emojis than there are any 72 ASCII characters.

This is x^3 vs y^72, where X is the total number of distinct emojs and Y is the total number of distinct ASCII characters.

24 bytes of data is not 24 bytes of entropy if there are only a couple thousand different possible inputs to produce all of the possible 24 byte sequences produced by those inputs.

For simplicity: picture having only two possible input buttons. Each one produces 1000 bytes of random-looking data, but each one always produces the exact same 1000-byte sequence, respectively. You have a maximum password of 1 button press. The "password" may contain 1000 bytes, but you only have one bit of entropy, because the attacker doesn't need to correctly guess all 1000 bytes, they only need to correctly guess which of the two buttons you pressed.

Of course, in practice, not all emojis are 24 bytes, and I'd assume few people are using emoji-only passwords, but the distinction between bytes of data and bytes of entropy is worth clarifying, regardless.

[zetanor]

The hash is 24 bytes. Even without an input character limit, you're likely to find tons of valid aliases for your 1000-character password within the 72-byte password space.

[cwbriscoe]

You could always pre-hash the password with sha256 or something similar to guarantee you won't go over the 72 byte limit.

[stavros]

I don't understand why this isn't a mandatory first step in the bcrypt algorithm itself. Who thought that a 72 byte limit was a good idea?

[testdelacc1]

Does anyone actually use emoji as a password.

[embedding-shape]

I never actually considered it until I read parent, and now I'm gonna try to start using it wherever it's supported, it's genius to use it for passwords as long as it's supported by the platform. Edit: Just to clarify, together with a password manager of course, otherwise I'd never have the patience for it.

[flysand7]

yea, me (pls dont crack)