Abstract—conventionally, single-line key field is used to input a key. The selection of a key depends on the factors of memorizability and security. The minimum key sizes for symmetric and asymmetric key cryptosystems are 80 and 160 bits, respectively. Advanced Encryption Standard (AES) sets the key sizes at 128, 192, and 256 bits. The asymmetric key cryptosystems that require a minimum key size of the private key are finite field cryptography (FFC) and elliptic curve cryptography (ECC). The corresponding sizes of private keys to the AES are 256, 384, and 512 bits, respectively. Here, we propose a 2-dimensional (2D) key input method to create high-entropy keys. The 2D key has the styles of multiline passphrase, crossword, ASCII art, colorful text, or spatial variation. It can resist dictionary attack and fulfill the demands of human-memorizable key sizes even until 256 bits, which is impossible by using the single-line passphrase. Special Chinese-character-encoded passphrase generates 13 ASCII characters for every Chinese character. 2D key also allows the creation of memorizable public-key cryptosystem (MePKC), where the private key is memorizable. MePKC provides mobility, lower cost and higher efficiency, which is better than the encrypted private key, split private key, and roaming private key.

Index Terms—User interfaces, human factors, memorizability,key/password security, Chinese-character-encoded passphrase,big memorizable secret, memorizable public-key cryptosystem(MePKC) (aka MoPKC - mobile public-key cryptosystem).

Kok-Wah Lee is with the Faculty of Engineering & Technology,Multimedia University, Jalan Ayer Keroh Lama, 75450 Bukit Beruang,Melaka, Malaysia (corresponding author to provide phone: 606-252-3320;fax: 606-231-6552; email: kwlee@mmu.edu.my; contact@xpreeli.com;E96LKW@hotmail.com).

Cite: Kok-Wah Lee,  "High-Entropy 2-Dimensional Key Input Method for Symmetric and Asymmetric Key Cryptosystems," International Journal of Computer and Electrical Engineering vol. 1, no. 1, pp. 1-8, 2009.