EBCDIC Encoding

Extended Binary Coded Decimal Interchange Code (EBCDIC) is an 8-bit computer character encoding created by IBM.

Used in punch cards, the character table has 256 codes and each code corresponds to one character (but not the same as ASCII).

To encode in EBCDIC from a binary message (this may be ASCII-encoded text), each 8-bit group is then encoded via the EBCDIC table.

Each ASCII code corresponds to an EBCDIC code and conversely, noting the ASCII and EBCDIC codes with a value between 0 and 255, then there is an equivalence that allows the encryption.

The encoded message can then be displayed via the ASCII table (resulting in an often unreadable encrypted message).

Example: The 5 characters' DCODE 'are coded 68,67,79,68,69 in ASCII but 196,195,214,196,197 in EBCDIC

By using the ASCII-EBCDIC equivalent table, any message can be decrypted.

Example: 196,195,214,196,197 in EBCDIC becomes 68,67,79,68,69 in ASCII, which corresponds to the letters' DCODE'.

EBCDIC data is encoded on 8 bits (256 possible codes).

Any reference to IBM or variants of the ASCII table are clues.

Late 1950s.