In the case of RC4 stream cipher, the very first step is to initialize the S Vector and T Vector. If the key is HELLO, then the value of T[0x0F] will be
Question
In the case of RC4 stream cipher, the very first step is to initialize the S Vector and T Vector. If the key is HELLO, then the value of T[0x0F] will be
Solution
In the RC4 stream cipher, the first step is to initialize the S vector and T vector. The T vector is initially a repetition of the key. If the key is 'HELLO', then it is repeated until the length of the T vector is 256 bytes.
The key 'HELLO' in ASCII is represented as [72, 69, 76, 76, 79] in decimal.
To find the value of T[0x0F] (or T[15] in decimal), we need to look at the 16th byte of the T vector. Since the key is only 5 bytes long, it will be repeated.
The 16th byte will be the first byte of the fourth repetition of the key, which is 'H'.
So, T[0x0F] will be 'H' or 72 in decimal.
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