Final answer:
The result of decrypting a DES-encrypted message in 1998 was the discovery of a vulnerability in the DES encryption algorithm.
Step-by-step explanation:
The result of the EFF decrypting a DES-encrypted message in 1998 was the discovery of a vulnerability in the DES encryption algorithm. DES, which stands for Data Encryption Standard, was found to have a key length that could be relatively easily cracked with modern computing power. This led to the development of more secure encryption algorithms, such as the Advanced Encryption Standard (AES), which is widely used today.