CODEWITHSUNDEEP
c#base64
Kevin Driedger
Kevin Driedger

Reputation: 54372

How do I encode and decode a base64 string?

  1. How do I return a base64 encoded string given a string?

  2. How do I decode a base64 encoded string into a string?

Upvotes: 1399

Views: 1536809

Answers (3)

Kevin Driedger
Kevin Driedger

Reputation: 54372

Encode

public static string Base64Encode(string plainText) 
{
    var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(plainText);
    return System.Convert.ToBase64String(plainTextBytes);
}

Decode

public static string Base64Decode(string base64EncodedData) 
{
    var base64EncodedBytes = System.Convert.FromBase64String(base64EncodedData);
    return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
}

Upvotes: 2479

juliushuck
juliushuck

Reputation: 1694

URL safe Base64 Encoding/Decoding

public static class Base64Url
{
    public static string Encode(string text)
    {
        return Convert.ToBase64String(Encoding.UTF8.GetBytes(text)).TrimEnd('=').Replace('+', '-')
            .Replace('/', '_');
    }

    public static string Decode(string text)
    {
        text = text.Replace('_', '/').Replace('-', '+');
        switch (text.Length % 4)
        {
            case 2:
                text += "==";
                break;
            case 3:
                text += "=";
                break;
        }
        return Encoding.UTF8.GetString(Convert.FromBase64String(text));
    }
}

Upvotes: 20

Qwertie
Qwertie

Reputation: 17196

For those that simply want to encode/decode individual base64 digits:

public static int DecodeBase64Digit(char digit, string digit62 = "+-.~", string digit63 = "/_,")
{
    if (digit >= 'A' && digit <= 'Z') return digit - 'A';
    if (digit >= 'a' && digit <= 'z') return digit + (26 - 'a');
    if (digit >= '0' && digit <= '9') return digit + (52 - '0');
    if (digit62.IndexOf(digit) > -1)  return 62;
    if (digit63.IndexOf(digit) > -1)  return 63;
    return -1;
}

public static char EncodeBase64Digit(int digit, char digit62 = '+', char digit63 = '/')
{
    digit &= 63;
    if (digit < 52)
        return (char)(digit < 26 ? digit + 'A' : digit + ('a' - 26));
    else if (digit < 62)
        return (char)(digit + ('0' - 52));
    else
        return digit == 62 ? digit62 : digit63;
}

There are various versions of Base64 that disagree about what to use for digits 62 and 63, so DecodeBase64Digit can tolerate several of these.

Upvotes: 5

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