To decrypt a double transposition, construct a block with the right number of rows under the keyword, blocking off the short columns. Write the cipher in by columns, and read it out by rows.

The German police made the mistake in late 1941 of switching from the rather strong Double Transposition cipher to the more ... begin by choosing a period or number of letters (say, seven ...

CYB-AES implements Rijndael cipher encoding and decoding in compliance with the NIST Advanced Encryption Standard. It supports all of the available key-sizes (128 ...