Tool to decrypt / encrypt using Base 37 (Alphanumeric + Separator) Cipher, an ideal base to encode alphanumeric strings with a number (and vice versa) with the mot common 37 characters (26 letters, 10 digits and 1 separator).

Base 37 Cipher - dCode

Tag(s) : Mathematics, Cryptography

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Base 37 is an arithmetic base made up of 37 symbols. It is used in practice to store text with the 36 alphanumeric characters (26 letters of the alphabet `ABCDEFGHIJKLMNOPQRSTUVWXYZ` and 10 digits `0123456789`) accompanied by an additional character, a separator such as space or underscore `_` (low dash).

Any whole number (in base 10, decimal) has a base 37 conversion (therefore a writing with the 37 characters above), and conversely any word or sentence (using these 37 symbols) has a base 10 conversion.

Base 37 encryption is based on arithmetic base change calculations (the conversion from base 37 to base 10).

__Example:__ To code the 3 characters `B37` in base 37 using the 37 symbols `0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_`, start by converting each character to base 10 according to their value/rank: `B=11`, `3=3`, '7= 7' and apply the base change: $ 11 \times 37^2 + 3 \times 37^1 + 7 \times 37^0 = 15177 $

Several sets of 37 symbols are possible for the base 37, they differ according to the order of the elements (digits, letters, separator).

Mathematically, the most used is `09AZ_` (numbers, letters, separator)

Symbols | 0 | 1 | 2 | 3 | … | 8 | 9 | A | B | C | … | X | Y | Z | _ |

Values | 0 | 1 | 2 | 3 | … | 8 | 9 | 10 | 11 | 12 | … | 33 | 34 | 35 | 36 |

In cryptography, it is preferred `AZ09_` (letters, numbers, separator)

Symbols | A | B | C | … | Y | Z | 0 | 1 | 2 | 3 | … | 7 | 8 | 9 | _ |

Values | 0 | 1 | 2 | … | 24 | 25 | 26 | 27 | 28 | 29 | … | 33 | 34 | 35 | 36 |

But it is possible to use other combinations, such as those starting with the separator `_AZ09` or `_09AZ`, or the variant `09_AZ` or `AZ_09`.

Base-37 decryption is the conversion of *encoded* numbers (in base 10) to the base 37.

__Example:__ Decode the message `571923`. $ 571923 = 11 \times 37^3 + 10 \times 37^2 + 28 \times 37^1 + 14 \times 37^0 $ so `[11,10,28,14]` in base 37 and `11=B`, `10=A`, `28=S`, `14=E`, that gives the plain message `BASE`.

A base 37 code is theoretically made up of a single large decimal number of length proportional to that of the message.

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Cite as source (bibliography):

*Base 37 Cipher* on dCode.fr [online website], retrieved on 2024-09-14,

base,37,alphanumeric,alphabet,letter,digit,separator

https://www.dcode.fr/base-37-cipher

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