This article presents a detailed study on the enhancement of the International Data Encryption Algorithm (IDEA) by scaling its block and key sizes. The original IDEA algorithm, operating on 64-bit blocks with a 128-bit key, is modified to use 128-bit blocks and a 256-bit key. The mathematical basis for these modifications is thoroughly explained, focusing on improving security against modern cryptographic attacks such as birthday and brute-force attacks. The proposed algorithm involves expanding the round functions and key schedule to accommodate the larger block and key sizes. The security and performance implications of these changes are discussed, highlighting the increased resistance to cryptanalysis and potential computational overhead. Additionally, the use of SHA-256 for key derivation is examined to ensure robust and uniformly random key material.