Substitution Cipher Technique and Transposition Cipher Technique
Substitution Cipher Technique:
In Substitution Cipher Technique plain text characters are replaced with other characters, numbers and symbols as well as in substitution Cipher Technique, character’s identity is changed while its position remains unchanged.
Transposition Cipher Technique:
Transposition Cipher Technique rearranges the position of the plain text’s characters. In transposition Cipher Technique, The position of the character is changed but character’s identity is not changed.
Difference between Substitution Cipher Technique and Transposition Cipher Technique:
S.NOSubstitution Cipher TechniqueTransposition Cipher Technique
1.In substitution Cipher Technique, plain text characters are replaced with other characters, numbers and symbols.In transposition Cipher Technique, plain text characters are rearranged with respect to the position.
2.Substitution Cipher’s forms are: Mono alphabetic substitution cipher and poly alphabetic substitution cipher.Transposition Cipher’s forms are: Key-less transposition cipher and keyed transposition cipher.
3.In substitution Cipher Technique, character’s identity is changed while its position remains unchanged.While in transposition Cipher Technique, The position of the character is changed but character’s identity is not changed.
4.In substitution Cipher Technique, The letter with low frequency can detect plain text.While in transposition Cipher Technique, The Keys which are nearer to correct key can disclose plain text.
5.The example of substitution Cipher is Caesar Cipher.The example of transposition Cipher is Rail Fence Cipher.
Difference between Block Cipher and Stream Cipher
Block Cipher and Stream Cipher belongs to the symmetric key cipher. These two block ciphers and stream cipher are the methods used for converting the plain text into ciphertext.
The main difference between a Block cipher and a Stream cipher is that a block cipher converts the plain text into cipher text by taking plain text’s block at a time. While stream cipher Converts the plain text into cipher text by taking 1 byte of plain text at a time.
Let’s see the difference between them:
S.NOBlock CipherStream Cipher
1.Block Cipher Converts the plain text into cipher text by taking plain text’s block at a time.Stream Cipher Converts the plain text into cipher text by taking 1 byte of plain text at a time.
2.Block cipher uses either 64 bits or more than 64 bits.While stream cipher uses 8 bits.
3.The complexity of block cipher is simple.While stream cipher is more complex.
4.Block cipher Uses confusion as well as diffusion.While stream cipher uses only confusion.
5.In block cipher, reverse encrypted text is hard.While in-stream cipher, reverse encrypted text is easy.
6.The algorithm modes which are used in block cipher are ECB (Electronic Code Book) and CBC (Cipher Block Chaining).The algorithm modes which are used in stream cipher are CFB (Cipher Feedback) and OFB (Output Feedback).
7.Block cipher works on transposition techniques like rail-fence technique, columnar transposition technique, etc.While stream cipher works on substitution techniques like Caesar cipher, polygram substitution cipher, etc.
8.Block cipher is slow as compared to a stream cipher.While stream cipher is fast in comparison to block cipher.
