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Submitted URL: https://www.hcidata.info/base64.htm#b64
Effective URL: https://www.hcidata.info/base64.htm
Submission: On November 28 via api from LU — Scanned from GB
Effective URL: https://www.hcidata.info/base64.htm
Submission: On November 28 via api from LU — Scanned from GB
Form analysis 1 forms found in the DOM
<form action="" onsubmit="this.hex2.value = hexAsHex(this.ascii.value);this.hex.value = hex2Char(this.ascii.value);return false">
<h2><a name="b64"></a>Base 64 Encoded Data</h2>
<textarea cols="80" rows="10" name="b64">TWFyeSBoYWQgYSBsaXR0bGUgbGFtYi4uLiBASktMTU5PUFpbXF1eX2BhamtsbW5ven1+
</textarea>
<br>
<input type="submit" value=" Convert base 64 data (above) to ASCII text (below) " onclick="this.form.ascii.value = b64ToA(this.form.b64.value)">
<br>
<br>
<input type="submit" value=" Convert ASCII text (below) to base 64 data (above) " onclick="this.form.b64.value = aToB64(this.form.ascii.value)">
<h2>ASCII text</h2>
<p>Note: the symbol ∅ <!-- 0x2205 or #8709 --> replaces any NULL (0x00) character.</p>
<textarea cols="80" rows="10" name="ascii"></textarea>
<h2>ASCII text translated to Hexadecimal text</h2>
<textarea cols="80" rows="10" name="hex"></textarea>
<h2>ASCII text translated to Hexadecimal</h2>
<textarea cols="80" rows="10" name="hex2"></textarea>
</form>Text Content
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Convert Base 64 encoded data to ASCII Text
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Go to Base64 Convertor
WHAT IS BASE 64 ENCODED DATA?
Put simply, base64 encoded data is a string of character that contains only a-z,
A-Z, 0-9, + and / characters and is often used in situations when sending
non-text information via a text only transmission protocol.
WHY USE BASE 64 ENCODING?
The transport system of e-mail protocol is designed for sending plain ASCII
text. The plain ASCII text includes a-z, A-Z, 0-9, ", %, &, ', (, ), *, +, -, _
and , (the comma). They will be referred to as the universal ASCII character
set. There are other ASCII characters, but these are not universal. If an e-mail
is sent using non-universal character (for example the £ symbol) the receiver of
the e-mail may see a completely different character on their screen or printer.
The situation is ever worse when trying to send e-mails in non English
languages. Often these languages will have characters that are not part of the
ASCII set. What is needed is a method to convert non-universal ASCII characters
to a common form. This common form is called Base64 encoding.
WHAT DOES BASE 64 ENCODING DO?
Base 64 Encoding takes a stream of characters and converts them to characters
that belong to the universal ASCII character set. Once a stream of characters
has been converted to characters that belong to the universal ASCII character
set (Base 64 encoded) they can be transported with ease over the Internet using
the e-mail protocols.
HOW DOES BASE 64 ENCODING WORK?
ASCII characters belong to the 256 byte character space and includes the usual
alpha, numeric, special characters (e.g. %), control characters (e.g. CR, LF,
BELL) and other characters. Each character is 8 bits in size. For some languages
the ASCII character set cannot be used (e.g. oriental pictographic languages).
These use a UNICODE character set where each characters needs 16 bits to
represent it.
The number of bits per character is not a problem for Base 64 Encoding. Base 64
Encoding takes a stream of bits and converts them to 8 bit characters that
belong to the universal ASCII character set. Base 64 Encoding does not care
about how many bits (8 or 16) are necessary to make a character as it works at
the bit level. Once a stream of bits have been converted to characters that
belong to the universal ASCII character set (Base 64 encoded) they can be
transported with ease over the Internet using the e-mail protocols.
Base64 Encoding takes three bytes of character data (3 ASCII characters or 1½
UNICODE character) and produces four bytes of data from the universal character
set. That is, Base64 Encoding takes 24 bits of input data and converts it to 32
bits of encoded data.
Base64 Encoding does not care what the data is. If the data contains line feeds,
nulls or special characters, Base64 Encoding does not care - it simply sees it
as a sting of bytes.
ENCODING "MARY HAD" TO BASE 64
In this example we are using a simple text string ("Mary had") but the principle
holds no matter what the data is (e.g. graphics file). To convert each 24 bits
of input data to 32 bits of output, Base 64 encoding splits the 24 bits into 4
chunks of 6 bits. The first problem we notice is that "Mary had" is not a
multiple of 3 bytes - it is 8 bytes long. Because of this, the last group of
bits is only 4 bits long. To remedy this we add two extra bits of '0' and
remember this fact by putting a '=' at the end. If the text string to be
converted to Base 64 was 7 bytes long, the last group would have had 2 bits. In
this case we would have added four extra bits of '0' and remember this fact by
putting '==' at the end.
Each of these groups is then converted to a decimal number from 0 to 63. Base 64
gets its name from the fact that there are 64 states for each element. This is
the same as decimal being called Base 10 are there are 10 states (0-9) for each
element.
And finally, the decimal number is used as an index into the universal ASCII
character set of
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/ to give the
Base 64 Encoded string.
In our example:
ASCII textMary had Hex representation of text4D 61 72 79 20 68 61 64 Bit
representation of text grouped by bytes01001101 01100001 01110010 01111001
00100000 01101000 01100001 01100100 Bit representation of text in groups of 6
bits 010011 010110 000101 110010 011110 010010 000001 101000 011000 010110
010000= Decimal representation of text in groups of 6 bits 19 22 05 50 30 18 01
40 24 22 16= Base 64 encoded stringTWFyeSBoYWQ=
DECODING "TWFYESBOYWQ=" FROM BASE 64 TO ASCII
The first thing to note is the '=' at the end of the Base 64 encoded string. A
Base 64 encoded string will have zero, one or two '='s at the end. As '=' is not
part of the Base 64 encoding, it can only ever appear at the end and has a
special meaning.
The stages to convert the Base 64 encoded data to ASCII is:
1. Take each letter and find its position offset (0-63) within
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/ to give us
11 decimal numbers
2. These decimal numbers are converted to bit strings, each with 6 bits
3. As there was a '=' at the end of the Base 64 encoded data, remove 2 '0's
from the end of the bit string. Had there been two '='s at the end of the
Base 64 encoded data, 4 '0's would have been removed from the end of the bit
string.
4. Split the bits into groups of 8
5. Use each group of 8 bits to be the ASCII code for an ASCII character or
ASCII control code
BASE 64 ENCODED DATA
TWFyeSBoYWQgYSBsaXR0bGUgbGFtYi4uLiBASktMTU5PUFpbXF1eX2BhamtsbW5ven1+
ASCII TEXT
Note: the symbol ∅ replaces any NULL (0x00) character.
ASCII TEXT TRANSLATED TO HEXADECIMAL TEXT
ASCII TEXT TRANSLATED TO HEXADECIMAL
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Last Updated: Monday, 04-Feb-2019
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