Tasks for students

Decrypt the following cryptograms on the base of the characters frequency occurrence. Reveal the key parameters a and b$,$ that create affine cipher y $=$ ax $+$ b$.$

$1)$ KSBJYKSBEIGEGSQWYYFATGIFATGIEYFIYG

$2)$ CPCDDBECXCOUEEDYXWQFWRCACO

$3)$ CFHMUPJMPPUUJCFHMUPJMPJUUJ

$4)$ AIPIBFIIBCBYXLCLIAOVIOPOCROTRIXIVI

$5)$ ENNEUTBYOBVKZULJNNEUT

$6)$ RIPRPQQRRPHRIPQQRWDGIPRPHRIJCP

$7)$ PHCQDGJWPAHUAPHCQDGJCXRPFHBPRHFHUIPHQGIDZPHQGIDHUAZXRP

$8)$ YEQAQQWHHEQAQTEQTOIRITJANEQAQ

$9)$ JYBNJGJWXTXWGJNBYJ

$10)$ EOEREXLEREKERELXEREOE

Please, fill the empty cells with proper contents $($key numbers and the plaintext$).$

$1$ Given ciphertext KSBJYKSBEIGEGSQWYYFATGIFATGIEYFIYG

a $=$ b $=$

Found plaintext

$2$ Given ciphertext CPCDDBECXCOUEEDYXWQFWRCACO

a $=$ b $=$

Found plaintext

$3$ Given ciphertext CFHMUPJMPPUUJCFHMUPJMPJUUJ

a $=$ b $=$

Found plaintext

$4$ Given ciphertext AIPIBFIIBCBYXLCLIAOVIOPOCROTRIXIVI

a $=$ b $=$

Found plaintext

$5$ Given ciphertext ENNEUTBYOBVKZULJNNEUT

a $=$ b $=$

Found plaintext

$6$ Given ciphertext RIPRPQQRRPHRIPQQRWDGIPRPHRIJCP

a $=$ b $=$

Found plaintext

$7$ Given ciphertext PHCQDGJWPAHUAPHCQDGJCXRPFHBPRHFHUIPHQGIDZPHQGID

HUAZXRP

a $=$ b $=$

Found plaintext

$8$ Given ciphertext YEQAQQWHHEQAQTEQTOIRITJANEQAQ

a $=$ b $=$

Found plaintext

$9$ Given ciphertext JYBNJGJWXTXWGJNBYJ

a $=$ b $=$

Found plaintext

$10$ Given ciphertext EOEREXLEREKERELXEREOE

a $=$ b $=$

Found plaintext