[API Proposal]: Base64 parity with Base64Url #121454
Description
Background and motivation
The API on Base64Url is very nice. However, there are no equivalents for the things that deal with UTF-16 instead of UTF-8 on Base64 and the UTF-16 base64 functionality on Convert is not as nice.
Here's an example: using Convert, I can't tell if it has failed due to invalid input or destination-too-small. This is actually getting in my way right now in a use case where I want decode only some bytes from base64. I went to copy some code that used Base64Url and was surprised that just dropping the Url suffix didn't work.
using System.Buffers.Text;
using System.Security.Cryptography;
byte[] bytes = new byte[100_000];
RandomNumberGenerator.Fill(bytes);
string base64UrlInput = Base64Url.EncodeToString(bytes);
string base64Input = Convert.ToBase64String(bytes);
string badInput = "@#$!!@#";
byte[] buffer = new byte[1_000];
// Output of TryFromBase64Chars does not distinguish between bad input and destination too small.
{
Console.WriteLine();
Console.WriteLine("Bad input vs Convert.TryFromBase64Chars.");
bool success = Convert.TryFromBase64Chars(badInput, buffer, out int bytesWritten);
Console.WriteLine("bytesWritten: " + bytesWritten);
Console.WriteLine(" success: " + success);
}
{
Console.WriteLine();
Console.WriteLine("Too much input vs Convert.TryFromBase64Chars");
bool success = Convert.TryFromBase64Chars(base64Input, buffer, out int bytesWritten);
Console.WriteLine("bytesWritten: " + bytesWritten);
Console.WriteLine(" success: " + success);
}
// Output of DecodeFromChars is perfect, but it's only available on Base64Url.
{
Console.WriteLine();
Console.WriteLine("Too much input vs Base64Url.DecodeFromChars");
var status = Base64Url.DecodeFromChars(base64UrlInput, buffer, out int charsConsumed, out int bytesWritten);
Console.WriteLine("charsConsumed: " + charsConsumed);
Console.WriteLine(" bytesWritten: " + bytesWritten);
Console.WriteLine(" status : " + status);
}
{
Console.WriteLine();
Console.WriteLine("Bad input vs Base64Url.DecodeFromChars");
var status = Base64Url.DecodeFromChars(badInput, buffer, out int charsConsumed, out int bytesWritten);
Console.WriteLine("charsConsumed: " + charsConsumed);
Console.WriteLine(" bytesWritten: " + bytesWritten);
Console.WriteLine(" status : " + status);
}Output:
Bad input vs Convert.TryFromBase64Chars.
bytesWritten: 0
success: False
Too much input vs Convert.TryFromBase64Chars
bytesWritten: 0
success: False
Too much input vs Base64Url.DecodeFromChars
charsConsumed: 1332
bytesWritten: 999
status : DestinationTooSmall
Bad input vs Base64Url.DecodeFromChars
charsConsumed: 0
bytesWritten: 0
status : InvalidData
API Proposal
(Hitting submit early to save a draft and I will come back and populate this with full list of newly proposed API. Basically, it would be to mirror any functionality that's on Base64Url but not Base64 onto Base64.)
API Usage
(Pending)
Alternative Designs
No response
Risks
No response