Does the security margin of Kalyna block cipher double per for additional 4 rounds? Would be possible to create a version of it with larger key sizes?

phantomcraft

7/27/23, 1:52 AM

I believe this question should be directed to the authors of Kalyna block cipher, but I think they cannot answer me because of the war they are facing in their country actually.

I know that AES uses this criteria for adjusting the rounds in accord to different key sizes: [key size]/32+6

Kalyna block cipher has 10 rounds for 128-bits of key size, 14 for 256-bits and 18 for 512-bits. I can see that for each duplication in the key size, four additional rounds are added. am I right or is there other criteria for calculating the additional rounds per increase in key lenght in Kalyna block cipher?

Another question:

Is it possible to create a version of Kalyna block cipher with larger key sizes such as 1024 or 2048-bits? I'm not a cryptographer (neither a good English reader) and I don't know how to read C code (there is reference implementations of this cipher along the Internet).

IF was possible to create modified versions of Kalyna with larger key sizes, should I add 4 rounds per each duplication in the key size based on fact that Kalyna uses four additional rounds per duplication in the key length in its official version?

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SAI Peregrinus

7/27/23, 2:08 AM

Symmetric key sizes over 256 bits are a sign of an incompetent designer. They provide no practical security increase, only a performance decrease. Poor performance often leads to people omitting encryption entirely, so it can be a security decrease.

phantomcraft

7/27/23, 11:54 PM

@SAIPeregrinus Well, Threefish has a key size up to 1024-bits and is yet quite fast and secure.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Does the security margin of Kalyna block cipher double per for additional 4 rounds? Would be possible to create a version of it with larger key sizes?

TH: ขอบความปลอดภัยของ Kalyna block cipher เป็นสองเท่าสำหรับรอบเพิ่มเติม 4 รอบหรือไม่ เป็นไปได้ไหมที่จะสร้างเวอร์ชันที่มีขนาดคีย์ที่ใหญ่ขึ้น

RO: Se dublează marja de securitate a cifrului bloc Kalyna pentru 4 runde suplimentare? Ar fi posibil să se creeze o versiune a acestuia cu chei de dimensiuni mai mari?

RU: Удваивается ли запас прочности блочного шифра Kalyna за дополнительные 4 раунда? Можно ли создать его версию с большими размерами ключей?

VI: Biên độ bảo mật của mật mã khối Kalyna có tăng gấp đôi cho mỗi 4 vòng bổ sung không? Có thể tạo một phiên bản của nó với kích thước khóa lớn hơn không?

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