Use more compact encoding (like base64) instead of hex?

[unwriter]

The original proposal suggests hex encoding because that's the one that's most widely used at the moment.

However hex format is not the most ideal when it comes to passing around because of its large size.

Here's a quick benchmark:

╔══════════╤════════════════════════════════╤══════╗
║ type     │ content                        │ size ║
╟──────────┼────────────────────────────────┼──────╢
║ Original │ Lorem ipsum dolor sit amet, co │ 212  ║
║          │ nsectetur adipiscing elit. Pro │      ║
║          │ in ut tortor blandit, placerat │      ║
║          │ ipsum non, vehicula odio. Nam  │      ║
║          │ cursus, mi sed dictum posuere, │      ║
║          │ orci nulla ultricies elit, sit │      ║
║          │ amet iaculis erat mi ut orci.  │      ║
║          │                                │      ║
╟──────────┼────────────────────────────────┼──────╢
║ Base64   │ TG9yZW0gaXBzdW0gZG9sb3Igc2l0IG │ 284  ║
║          │ FtZXQsIGNvbnNlY3RldHVyIGFkaXBp │      ║
║          │ c2NpbmcgZWxpdC4gUHJvaW4gdXQgdG │      ║
║          │ 9ydG9yIGJsYW5kaXQsIHBsYWNlcmF0 │      ║
║          │ IGlwc3VtIG5vbiwgdmVoaWN1bGEgb2 │      ║
║          │ Rpby4gTmFtIGN1cnN1cywgbWkgc2Vk │      ║
║          │ IGRpY3R1bSBwb3N1ZXJlLCBvcmNpIG │      ║
║          │ 51bGxhIHVsdHJpY2llcyBlbGl0LCBz │      ║
║          │ aXQgYW1ldCBpYWN1bGlzIGVyYXQgbW │      ║
║          │ kgdXQgb3JjaS4=                 │      ║
╟──────────┼────────────────────────────────┼──────╢
║ Hex      │ 4c6f72656d20697073756d20646f6c │ 424  ║
║          │ 6f722073697420616d65742c20636f │      ║
║          │ 6e7365637465747572206164697069 │      ║
║          │ 7363696e6720656c69742e2050726f │      ║
║          │ 696e20757420746f72746f7220626c │      ║
║          │ 616e6469742c20706c616365726174 │      ║
║          │ 20697073756d206e6f6e2c20766568 │      ║
║          │ 6963756c61206f64696f2e204e616d │      ║
║          │ 206375727375732c206d6920736564 │      ║
║          │ 2064696374756d20706f7375657265 │      ║
║          │ 2c206f726369206e756c6c6120756c │      ║
║          │ 7472696369657320656c69742c2073 │      ║
║          │ 697420616d657420696163756c6973 │      ║
║          │ 2065726174206d69207574206f7263 │      ║
║          │ 692e                           │      ║
╚══════════╧════════════════════════════════╧══════╝

The hex format in this case increases the original message's size 2x.

Also shown on the table, the base64 encoding also increases the size but not as much as hex. Plus it's also a widely used format (although not as much as hex format due to its lack of readability), so base64 might be a better choice.

Some people have brought up other types of encoding schemes as well. Will need to consider if they're better than base64.

[unwriter]

One concern against base64 is that it includes certain special characters like /, +, and =, each of which is already being used for special purposes in the conventional URI scheme (/ being used as a path identifier for example).

This issue could be ignored if the standard enforces a very strict and distinct grammar but will need to consider both pros and cons first.

[ghost]

There's browser safe base64. This is a good idea given that QRs are significantly smaller this way.