As such, it has the weaknesses of all substitution ciphers.

For a simple substitution cipher, the number of possible keys is 26!

Substitution ciphers are not safe enough to use for important messages.

In a substitution cipher, a rule is used to change each letter of the message, one at a time.

Holmes comes to realize that it is a substitution cipher.

Substitution ciphers can be broken by an idea called frequency analysis.

Another method of substitution cipher is based on a keyword.

One type of substitution cipher, the one-time pad, is quite special.

In its basic form it is a simple one-to-one substitution cipher.

In it he described the first known digraphic substitution cipher.

There are a number of different types of substitution cipher.

What Sanchez worked out was a simple monoalphabetic substitution cipher.

This is just a code version of a polyalphabetic substitution cipher.

Some substitution ciphers involve using numbers instead of letters.

While Caesar's was the first recorded use of this scheme, other substitution ciphers are known to have been used earlier.

A message that has been changed by a substitution cipher will have different common letters, but this gives a hint about the rule.

Atbash is a simple substitution cipher for the Hebrew alphabet.

There is no record at that time of any techniques for the solution of simple substitution ciphers.

The Vigenere is probably the most famous example of a polyalphabetic substitution cipher.

All the encrypted hints were a simple substitution cipher.

A simple transposition and substitution cipher used for broadcasting navigation warnings.

The Caesar cipher is one example of a substitution cipher.

"It works for all reflectional substitution ciphers, including the Atbash.

Players are frequently given certain known letters to begin with, but must then figure out the remaining letter mappings in a simple substitution cipher.

This is a very simple substitution cipher.