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Barcode 39

Tool to decrypt Barcode 39. Code 39 (or Code 3 of 9 or Alpha39) is a normalized barcode system which is being replaced by Code 128.

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Barcode 39 -

Tag(s) : Character Encoding, Image Processing

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# Barcode 39

## Barcode 39 Generator

 Variante Code 39 (Recommanded) Extended Code 39 (for ASCII encoding)
 Checksum Ignore (no control) Add the control character Already included in the coded value
 Output format Image Binary Data 0=Empty and 1=Black bar Checksum value

### Options

 Output format Value/Text of the Barcode Image

### How to encrypt using Barcode 39 cipher?

Encryption uses an encoding table with 43 characters: the 26 capital letters, the 10 digits and some special characters (-, ., \$, /, +, % and ' ' (space). The character * can appear but it does not exist, it is only used as a delimiter for start and end.

Each character has 5 black bars and 4 white bars (9 elements in total) starting with black and alternating white and black. Each band can have 2 widths: narrow or wide (generally 3 times larger), so it is possible to binarize the code (1 for thin bands, and 0 for wide bands). Also, in these 9 elements, always 3 bands are larger, hence the name of code 39.

A barcode 39 starts with * and ends with *. Here is the character map:

Each character has 5 black bars and 4 white bars (9 elements in total), it is therefore possible to binarize the (1, 11 or 111 for black bands according to its width, 0, 00 or 000 for white bands). In these 9 elements there are 3 which are larger (between 2 and 3 times as wide) and 6 thinner. The code starts with * and ends with *.
 0 |||▮▮|▮|| 1 ▮||▮||||▮ 2 ||▮▮||||▮ 3 ▮|▮▮||||| 4 |||▮▮|||▮ 5 ▮||▮▮|||| 6 ||▮▮▮|||| 7 |||▮||▮|▮ 8 ▮||▮||▮|| 9 ||▮▮||▮|| A ▮||||▮||▮ B ||▮||▮||▮ C ▮|▮||▮||| D ||||▮▮||▮ E ▮|||▮▮||| F ||▮|▮▮||| G |||||▮▮|▮ H ▮||||▮▮|| I ||▮||▮▮|| J ||||▮▮▮|| K ▮||||||▮▮ L ||▮||||▮▮ M ▮|▮||||▮| N ||||▮||▮▮ O ▮|||▮||▮| P ||▮|▮||▮| Q ||||||▮▮▮ R ▮|||||▮▮| S ||▮|||▮▮| T ||||▮|▮▮| U ▮▮||||||▮ V |▮▮|||||▮ W ▮▮▮|||||| X |▮||▮|||▮ Y ▮▮||▮|||| Z |▮▮|▮|||| - |▮||||▮|▮ . ▮▮||||▮|| |▮▮|||▮|| \$ |▮|▮|▮||| / |▮|▮|||▮| + |▮|||▮|▮| % |||▮|▮|▮| * |▮||▮|▮||

A wide band is 3 times thicker than a thin band.

Example: A narrow black band would be coded 1 and a wide black band would be coded 111.

Example: *A* is coded |▮||▮|▮||▮||||▮||▮ |▮||▮|▮|| or in binary 1 000 1 0 111 0 111 0 1 0 111 0 1 0 1000 1 0 111 0 1000 1 0 111 0 111 0 1 0

### How to decrypt Barcode 39 cipher?

Decryption requires to perform a reading of the bar according to EAN-128 standard.

Many app for smartphones or laser handshowers facilitate this work.

Example: The message is |▮||▮|▮|| ||||▮▮||▮ ▮|▮||▮||| ▮|||▮||▮| ||||▮▮||▮ ▮|||▮▮||| |▮||▮|▮|| (alternating black and white stripes), check |▮||▮|▮|| at the beginning and the end to confirm it's a code 39 barcode. The replacement of each 9-bar group by their associated character in the table. Barcode value is DCODE.

Checksum is missing in this example

### How to calculate the checksum character?

Associate with each character the value of its position in the alphabet of 43 characters 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ-. \$/+% * (starting from 0)

Add these values and calculate the result modulo 43. The control character is the one in position (sum%43) in the alphabet.

### How to recognize 39 Barcode?

The barcode has a classic graphical form (black and white lines) or a binary equivalent (1 or B for black and 0 or W for white lines).

The barcode may have a variable length. It begins and ends with the character *.

### Why the barcode is named Code 39?

The bar code consists of lines in groups of 9 which 3 are wider, hence the name 3 of 9 or 39.

## Source code

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Cite as source (bibliography):
Barcode 39 on dCode.fr [online website], retrieved on 2024-09-10, https://www.dcode.fr/barcode-39

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