Concealment Ciphers vs. Running Key Ciphers

Both of these ciphers types are early or classical methods for producing cipher-text. Concealment ciphers work by concealing or hiding the plain-text message within another message.

Running-key ciphers rely on a simple square table of alphabets called a "tabula recta" and a chunk of text from a previously agreed-upon source called a "polyalphabetic source". The tabula recta is a table made up of rows of the alphabet, with each row computed by shifting the preceding letter to the left. The plain-text is substituted with chunks of text from the polyalphabetic source, and the cipher-text is then derived by the value in tabula recta. The "key" here is the polyalphabetic source. Table below shows a truncated tabula recta.

   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  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
B  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
C  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  B
D  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  A  B  c

Substitution Ciphers vs. Transposition Ciphers

Substitution ciphers work by replacing/substituting parts or the whole of the plain-text with something else. A key is used to predetermine how the substitution should take place.

Transposition ciphers, on the other hand, do not rely on substitution; instead, parts of the plain-text are moved or juggled around to hide the meaning of the original plaintext.