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// RSA Encryption scheme
p = 7 //Large prime numbers
q = 17 //Small values taken here for convenience of calculation
//and explanation
n = p*q
z = (p-1)*(q-1)
e = 5 // e<n and e & z are coprime
i=1
d = i
while(1==1) //Calcualtion of 'd' from e and z
if modulo(i*e,z)==1 then // (e*d)mod z = 1
d=i
break
end
i=i+1
end
printf("\nPublic Key: (%d,%d)\nPrivate Key: (%d,%d)\n\n",n,e,n,d)
PT = 'F' //Example plaintext in ASCII
P = ascii(PT)-ascii('A')+1 //Conversion of ASCII to integer code
//(A=1,B=2,C=3, ... )
printf("Plaintext: %s\n",PT)
printf("Plain text Integer code: %d\n\n\",P)
C = 1
for i = 1:e
C = modulo(C*P,n)
end
C = modulo(C,n)
printf("Encrypted Text Code: %d\n\n",C)
P=1
for i = 1:d
P = modulo(P*C,n)
end
PT = ascii(ascii('A')+P-1)
printf("Decrypted Text Code: %d\n",P) //Decryoted code
printf("Decrypted Text: %s\n",PT) //Conversion to plain text in ASCII
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