Difference among ECB, CBC, CFB, OFB, CTR mode

□ ECB(Electronic Code Book) : Encryption method(=Code book) using electronic equipment

○ Encryption(En) : En(P[i])
○ Decryption(De) : De(C[i])

□ CTR(CounTeR) : Counter is encrypted

○ Encryption(En→XOR) : XOR(En(CTR[i]), P[i])
○ Decryption(En→XOR) : XOR(En(CTR[i]), C[i])

□ CBC(Cipher Block Chaining) : XOR(=Chaining) with ciphertext(=Cipher block) and next step plaintext

○ Encryption(XOR→En) : En(XOR(P[i], C[i-1]))
○ Decryption(De→XOR) : XOR(De(C[i]), C[i-1])

□ CFB(Cipher FeedBack) : Ciphertext(=Cipher) is input of next step encryption algorithm(=Feedback)

○ Encryption(En→XOR) : XOR(En(C[i-1]), P[i])
○ Decryption(En→XOR) : XOR(En(C[i-1]), C[i])

□ OFB(Output FeedBack) : Result of the encryption algorithm(=Output) is the input to next step encryption algorithm(=Feedback)

○ Encryption(En→XOR) : XOR(En(IV)[i], P[i])
○ Decryption(En→XOR) : XOR(En(IV)[i], C[i])

P.S. Symbol information

- En:Encryption / De:Decryption
- C:Cipher text / P:Plain text
- i:Each step(Ex. Current step:i / one Previous step:i-1 / one Next step:i+1)