How should I interpret an input English text as 64-bit blocks while implementing the IDEA algorithm?

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I am implementing the IDEA) So there is a question: how is the input text interpreted?(as far as I am concerned the IDEA uses XOR,multiplication mod(2^16+1) and and addition mod(2^16) operations. So how should I interpret English letters into bits???). Any help is appreciated!

Posted 10-Oct-15 0:52am

Dzianis Igaravich Leanenka

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[no name] 10-Oct-15 7:04am

Only for information, that not everybody has to search:
https://en.wikipedia.org/wiki/International_Data_Encryption_Algorithm[^]

"English letters ": Until now I did not know that the letters are in English. I must, willy-nilly to learn.

Here an effort how letters are represented in bits:http://www.ascii-code.com/[^]

BillWoodruff 10-Oct-15 7:40am

Keep in mind that "English letters" (glyphs) may be encoded in a variety of ways, like ASCII, Unicode, etc.

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Bernhard Hiller · Answer 1 · 2015-10-10T04:16:00

Solution 1

If the text is written with ASCII encoding, you get 8bits per character. That is, you take 8 characters for one block of 64bits; you may need to feel up remaining space by e.g. \0.
For other encodings, the width is typically 16bits, then take 4 characters per 64bit block.

Posted 10-Oct-15 4:16am

Bernhard Hiller

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[no name] 10-Oct-15 10:27am

Pure ASCII is 7 bits

Patrice T · Answer 2 · 2015-10-10T06:50:00

In computers, a bit is the base of any data. For practical reasons, a group of 8 bits is used, the name is byte.
A byte is the minimum unit of data available. Absolutely every thing is made of bytes.
All you need is to cast anything to a byte array and feed the encryption routine with blocs of 8 bytes, no matter what they are. There is no interpreting to do, English letters or not.

C#

Encrypted_data = IDEA_Encrypt(Original_Data, Key);
// Original_Data is a bloc of 8 bytes containing anything
// Key is the encrypting key.
// Encrypted_data is the 8 bytes encrypted result
Decrypted_data = IDEA_Decrypt(Encrypted_Data, Key);
// Decrypted_data is equal to Original_Data, no matter what.