Tool for decoding or encoding with Base 92. Base 92 code allows binary information to be stored in ASCII format with minimal data loss.

Base 92 Encoding - dCode

Tag(s) : Character Encoding

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The 92 character alphabet used in Base 92 is indexed as follows:

(empty) | ~ | 9 | + | 19 | 5 | 29 | ? | 39 | I | 49 | S | 59 | ] | 69 | h | 79 | r | 89 | | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|

0 | ! | 10 | , | 20 | 6 | 30 | @ | 40 | J | 50 | T | 60 | ^ | 70 | i | 80 | s | 90 | } |

1 | # | 11 | - | 21 | 7 | 31 | A | 41 | K | 51 | U | 61 | _ | 71 | j | 81 | t | ||

2 | $ | 12 | . | 22 | 8 | 32 | B | 42 | L | 52 | V | 62 | a | 72 | k | 82 | u | ||

3 | % | 13 | / | 23 | 9 | 33 | C | 43 | M | 53 | W | 63 | b | 73 | l | 83 | v | ||

4 | & | 14 | 0 | 24 | : | 34 | D | 44 | N | 54 | X | 64 | c | 74 | m | 84 | w | ||

5 | ' | 15 | 1 | 25 | ; | 35 | E | 45 | O | 55 | Y | 65 | d | 75 | n | 85 | x | ||

6 | ( | 16 | 2 | 26 | < | 36 | F | 46 | P | 56 | Z | 66 | e | 76 | o | 86 | y | ||

7 | ) | 17 | 3 | 27 | = | 37 | G | 47 | Q | 57 | [ | 67 | f | 77 | p | 87 | z | ||

8 | * | 18 | 4 | 28 | > | 38 | H | 48 | R | 58 | \ | 68 | g | 78 | q | 88 | { |

In practice, only 91 signs are used in basic calculations, the 92nd (the tilde `~`) is only used to indicate an empty string.

To encode data in Base 92, cut the data into 13-bit blocks to make 2 base 91 characters (yes 91 and not 92).

__Example:__ `dCode` is written in binary (ASCII) `0110010001000011011011110110010001100101`

Blocking of 13 bits gives `0110010001000,0110110111101,1001000110010,1`

The converting `0110010001000` (base 2) gives ' 3208' (base 10) or 35×91+23. Character 35 of base 91 is `E` and character 23 is `9` whose block is coded `E9`.

Complete the last block with `0` on the right. Pad to 6 bits if the block contained 6 bits or less, otherwise pad to 13 bits.

__Example:__ The last block `1` (length 1 bit) is completed to `100000` (completed over 6 bits) or 32 in base 10, and symbol 32 is `B`.

The complete coded message is `E9H]U3B`

For each pair of characters, note the value of each symbol in the Base 92 alphabet. Multiply the first by 91 and add them.

__Example:__ Decode `9A2?VBWl` by splitting it into pairs `9A` `2?` `VB` `Wl`. The first character `9` has the index `23`, and `A` the code `31`. The calculation is 23×91+31=2124.

For each number obtained, convert it to binary, completing it if necessary on the left to obtain 13 bits.

__Example:__ 2124 in base 10 corresponds to `100001001100` in binary, as this number is only 12 bits, add an initial zero or `0100001001100`

The binary sequence obtained (by concatenation of 13-bit numbers) corresponds to the plain message. If the message was originally encoded in 8-bit ASCII, then each byte corresponds to an ASCII character.

__Example:__ The binary sequence is `01000010,01100001,01110011,01100101,00111001,00110010` or the 6 `Base92` characters

The message is composed of the 91 characters of the Base92 alphabet.

The character `~` appears alone or does not appear.

If the message length is odd, then the last character can only be among the first 64 characters of the alphabet.

Each 13-bit block can encode 2^13 = 8192 values, while 2 base 91 characters encode 91^2=8281 values. The encoding loss is therefore minimized for an alphabet of 91 symbols.

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Cite as source (bibliography):

*Base 92 Encoding* on dCode.fr [online website], retrieved on 2024-09-10,

92,base,base92,ascii,13,binary

https://www.dcode.fr/base92-encoding

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