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Week 97 — What is Base64 and how can data be encoded/decoded with it?

Question of the Week #97

What is Base64 and how can data be encoded/decoded with it?

5 Replies

Base64 allows to encode arbitrary binary data using ASCII characters (alphanumerical characters as well as +/=) as well as decoding it without losing any data. It is specified in RFC 4648. Java provides the Base64 class for that purpose. That class contains the methods getEncoder() and getDecoder() for encoding and decoding respectively. To encoder a byte[] to a Base64 String, the encodeToString method can be used on an object returned by Base64.getEncoder():

byte[] bytes = new byte[]{8, 1, 68, 4, 0, 68, -1, 13, 37, 0x13, 0x37};
String encoded = Base64.getEncoder().encodeToString(bytes);// CAFEBABE/w0lEzc=

byte[] bytes = new byte[]{8, 1, 68, 4, 0, 68, -1, 13, 37, 0x13, 0x37};
String encoded = Base64.getEncoder().encodeToString(bytes);// CAFEBABE/w0lEzc=

A String encoded with Base64 can then be decoded again using the decode method on an object returned by Base64.getDecoder(). Doing so returns the original bytes:

byte[] decoded = Base64.getDecoder().decode(encoded);//8, 1, 68, 4, 0, 68, -1, 13, 37, 19, 55

byte[] decoded = Base64.getDecoder().decode(encoded);//8, 1, 68, 4, 0, 68, -1, 13, 37, 19, 55

📖 Sample answer from dan1st

Eric McIntyre•4w ago

Base64 is a binary-to-text encoding scheme that converts binary data into an ASCII string format using a specific set of 64 characters, making it safe for transmission over text-based protocols. It encodes data by grouping three bytes (24 bits) into four characters (6 bits each) and often uses padding with = if necessary. You can easily encode and decode Base64 data using programming libraries; for example, in Python, you can use the base64 module for encoding and decoding operations. Base64 increases the size of the original data by about 33% and is commonly used in applications such as email and web data handling.

Submission from hemantgarg218

Eric McIntyre•4w ago

Base64 is an encoding that transforms the content in bytes to text using the 64 printable ascii chars... Java does have a built in class java.util.Base64, so to encode/decode:

public static String encode(String original) {
  java.util.Base64.getEncoder().encodeToString(original.getBytes());
}

public static String decode(String encoded) {
  new String(java.util.Base64.getDecoder().decode(encoded));
}

public static String encode(String original) {
  java.util.Base64.getEncoder().encodeToString(original.getBytes());
}

public static String decode(String encoded) {
  new String(java.util.Base64.getDecoder().decode(encoded));
}

Submission from viniciuspdionizio

Eric McIntyre•4w ago

Base64 is a data encoding scheme that allows binary data to be represented as printable (usually ASCII) characters for transmission through channels that do not permit binary data, such as HTTP or SMTP. It works by breaking up the data stream into 6-bit groups (ignoring the 8-bit byte boundaries). Each group is then mapped to a printable character in the Base64 alphabet. The alphabet usually consists of the 62 ASCII characters A-Z, a-z, and 0-9. The remaining 2 characters vary based on the particular standard. For instance, RFC 4648 specifies '/' and '='. In Java versions since 1.8, there are built in classes for handling Base64 data. The entry point is java.util.Base64, which contains static methods for acquiring encoders (binary-to-Base64) and decoders (Base64-to-binary). There are three different variants of the Base64 scheme represented, for common use cases.

Eric McIntyre•4w ago

Another common implementation is Apache Commons Codec, in the org.apache.commons.codec.binary package. Apache's implementation is very flexible, providing a number of options for controlling the encoding and decoding.

⭐ Submission from dangerously_casual

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Week 97 — What is Base64 and how can data be encoded/decoded with it?