bitcoin address with capital letters

[btc123thatthere]

I saw a bitcoin address on a video, and all of its letters were in capitals.

Is this common? Perhaps they made it this since it was in a video, making it harder to "copy & paste"?

Looked a bit weird.

[Pmalek]

Legacy and Nested SegWit addresses are case sensitive so you have to copy/paste those the way they are generated. You will see both uppercase and lowercase characters in those types of addresses.

Native SegWit addresses are different and are not case sensitive. They can either have all characters as uppercase or all characters as lowercase. You can't have a Native SegWit address with mixed uppercase and lowercase characters. I am pretty sure I remembered this correctly, but someone will chip in if I didn't.  

[BrewMaster]

bech32 addresses which are used for the SegWit addresses are not case sensitive so they can be represented in all caps letters too.
meaning both of these addresses (copied from BIP173) are the same:
bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4
BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4

the benefit of all upper case letters is smaller QR code when you want to encode an address as an image. this was not possible in base58 (aka legacy) addresses.

you can read more about this encoding here: https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki

[Charles-Tim]

I saw a bitcoin address on a video, and all of its letters were in capitals.

No more further explanation that bech32 addresses can either be in capital or small letter, but according to all the wallets I have used before, the bech32 addresses are in small letters and numbers, which should be the recommended way. Some people may want to change it to capital, this might lead to typo error, even if bech32 address can still point out few typo errors, it should not be recommended if the wallet someone is using uses small letter which I believe is the standard wallets are using which makes the QR code have smaller field.

[ranochigo]

No more further explanation that bech32 addresses can either be in capital or small letter, but according to all the wallets I have used before, the bech32 addresses are in small letters and numbers, which should be the recommended way. Some people may want to change it to capital, this might lead to typo error, even if bech32 address can still point out few typo errors, it should not be recommended if the wallet someone is using uses small letter which I believe is the standard wallets are using which makes the QR code have smaller field.

The way bech32 is designed is to make the address standard unambiguous. Those lookalike letters have already been eliminated and standardizing all of the characters to either be in uppercase or lowercase will reduce the chances of typos. It's fine for them to be represented in uppercase.

There is absolutely nothing wrong with representing them in uppercase. Wallets like Electrum will automatically convert it back into a lowercase string if you enter an address in uppercase. AFAICT, some wallets like Electrum represents bech32 addresses in lowercase when using the QR codes; nothing wrong just that not all follows the recommendation.

[BrewMaster]

AFAICT, some wallets like Electrum represents bech32 addresses in lowercase when using the QR codes; nothing wrong just that not all follows the recommendation.

it is not a recommendation to change the letter cases when turning them into QR code, it is an option that exists to server very special cases like if you wanted to print the address on a very small surface like a physical bitcoin otherwise it is best to stick to lower case because the other wallet that reads it may not be as sophisticated to recognize upper case!

[ranochigo]

it is not a recommendation to change the letter cases when turning them into QR code, it is an option that exists to server very special cases like if you wanted to print the address on a very small surface like a physical bitcoin otherwise it is best to stick to lower case because the other wallet that reads it may not be as sophisticated to recognize upper case!

For presentation, lowercase is usually preferable, but inside QR codes uppercase SHOULD be used, as those permit the use of alphanumeric mode, which is 45% more compact than the normal byte mode.

It's specified in the BIP though. I don't think it's difficult for wallets to change it back into lowercase. Definitely not necessary and wouldn't affect normal use, just wanted to align with the BIP. Bitcoin Core is one of the many wallets that represents both their URI and QR codes in caps.

[DaveF]

...
bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4
BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4
...

....
it is not a recommendation to change the letter cases when turning them into QR code, it is an option that exists to server very special cases like if you wanted to print the address on a very small surface like a physical bitcoin otherwise it is best to stick to lower case because the other wallet that reads it may not be as sophisticated to recognize upper case!

When doing demos / discussions I tend to put everything in uppercase because it tends to be a bit larger so you can read it better. Don't think about reading it on your PC screen, think about it in a youtube video or on a projected screen in the front of a room. Also I tend to use bogus / invalid addresses so nobody can copy / paste and send someplace they should not so it does mater as much in terms of invalid things. So there is that.

I would not want to change any letter case ever. QR code or anything else, 10 or 15 years from now if some standard changes having to track down "wallet x" because it will read some changed data could be a nightmare.

-Dave

[btc123thatthere]

it is not a recommendation to change the letter cases when turning them into QR code, it is an option that exists to server very special cases like if you wanted to print the address on a very small surface like a physical bitcoin otherwise it is best to stick to lower case because the other wallet that reads it may not be as sophisticated to recognize upper case!

For presentation, lowercase is usually preferable, but inside QR codes uppercase SHOULD be used, as those permit the use of alphanumeric mode, which is 45% more compact than the normal byte mode.

It's specified in the BIP though. I don't think it's difficult for wallets to change it back into lowercase. Definitely not necessary and wouldn't affect normal use, just wanted to align with the BIP. Bitcoin Core is one of the many wallets that represents both their URI and QR codes in caps.

When I produce a QR code to show a receival address in Bitcoin Core, it comes up with both lowercase and uppercase letters in the address. (Core v0.18.0, Qt v5.9.7, old, I know...).

[ranochigo]

When I produce a QR code to show a receival address in Bitcoin Core, it comes up with both lowercase and uppercase letters in the address. (Core v0.18.0, Qt v5.9.7, old, I know...).

Does it start with a 3 or 1? Those are case sensitive.

Bech32 is not case sensitive and should either have all of it's letter in uppercase or lowercase.

[Evilish]

I won't mention the case insensitivity of bech32 addresses because it's already been mentioned but thought I'd link you to this thread that contains many unusual addresses.

Rare address hall of fame

Linked on that thread I found a stackoverflow question under which a user mentions a legacy address that is all uppercase.

1QBDLYTDFHHZAABYSKGKPWKLSXZWCCJQBX

This address is one of a kind as far as I am aware and it appears that it's owned by the autor of Armory Bitcoin Client. I have not seen any other similar addresses.

If you were to generate an address similar to this using vanitygen it would take a long long time unless you get extremely lucky.

[WanderingPhilospher]

All uppercase/capital letters are fairly easy to come by...

1AFVLMVBDNWHBRLANSNLY1WWPGQGPGLQPK

So yes, they do exist, but they do look "odd"

Edit: Ok, maybe all caps is a little tougher than expected 

[NeuroticFish]

If you were to generate an address similar to this using vanitygen it would take a long long time unless you get extremely lucky.

That's incorrect. Vanitygen accepts regular expressions and although I am not great at regexp I still managed, after 3 minutes of searching the internet, to give the correct parameters to vanitygen and receive all-uppercase addresses. And in a couple of minutes, on my CPU, I already got 3 of them.

[WanderingPhilospher]

If you were to generate an address similar to this using vanitygen it would take a long long time unless you get extremely lucky.

That's incorrect. Vanitygen accepts regular expressions and although I am not great at regexp I still managed, after 3 minutes of searching the internet, to give the correct parameters to vanitygen and receive all-uppercase addresses. And in a couple of minutes, on my CPU, I already got 3 of them.

Looks like your addresses all have numbers in them as well. So they are not all capital letters. Can you try for only all CAPS?

[pooya87]

All uppercase/capital letters are fairly easy to come by...
1AFVLMVBDNWHBRLANSNLY1WWPGQGPGLQPK

According to @NeuroticFish "benchmark" this type of addresses don't seem to be that tough but still you should keep in mind that creating a base58 string with a checksum where the string is bruteforced is a lot easier to creating an actual address using the private key. Considering this address is never used I'm guessing it is the former type.

[NeuroticFish]

Looks like your addresses all have numbers in them as well. So they are not all capital letters. Can you try for only all CAPS?

Sure, but I expect to take much longer. After some 10 minutes on the same 8 threads I've got no result.
I will leave it on 3 threads instead of 8 so I can do my work too, but I will leave it for much longer, let's see what happens.
However, the address you have posted had digit in it  so I was not "cheating".

[WanderingPhilospher]

Looks like your addresses all have numbers in them as well. So they are not all capital letters. Can you try for only all CAPS?

Sure, but I expect to take much longer. After some 10 minutes on the same 8 threads I've got no result.
I will leave it on 3 threads instead of 8 so I can do my work too, but I will leave it for much longer, let's see what happens.
However, the address you have posted had digit in it  so I was not "cheating".

Very true, that's why I posted my edit 
I'll leave a few threads running as well. See what we come up with

[Evilish]

If you were to generate an address similar to this using vanitygen it would take a long long time unless you get extremely lucky.

That's incorrect. Vanitygen accepts regular expressions and although I am not great at regexp I still managed, after 3 minutes of searching the internet, to give the correct parameters to vanitygen and receive all-uppercase addresses. And in a couple of minutes, on my CPU, I already got 3 of them.

I am correct. Try generating one with "all uppercase letters" and containing no numbers. I recall someone mentioning a while back it would take 70 days to generate one. Might be less now with ever increasing CPU/GPU power, but nowhere near 3 minutes.

Please give it a shot and let me know if you're able to generate one with the criteria I mentioned above.

[NeuroticFish]

Try generating one with "all uppercase letters" and containing no numbers.

I guess that I have misunderstood your initial criteria. You've seen what I've generated. And yes, I also admitted that uppercase-letters-only is much more difficult/should take much longer.
As for now, on 3 threads (of 8 ) I have no results. The most it ran it was some 3 hours, since I needed a restart for more important things. And this is also the reason I won't be able to run a 70-days test