The condition of the world experiencing the COVID-19 pandemic has resulted in some daily activities limited by health protocols. The Indonesian government's policy in the academic field has forced STIE Mandala Jember, as one of the private universities, to implement online-based new student admissions. The registrant's identity must be kept confidential during the online-based new student registration process, so the running system needs an identity coding (encryption) process. Hill Cipher is a cryptographic algorithm that utilizes the multiplication of matrix inverse operations. In ordinary Hill Cipher, to encrypt the entire plaintext, a key is needed. In this paper, we will modify the Hill Cipher named Hill Cipher Chain. The process of chained Hill Cipher will encrypt and decrypt the primary key based on the previous character. Firstly, we will encrypt the primary key with the key from the next column of the database. In this case, we use the name column. The encryption result will be used as a key for the subsequent character encryption. Implementation of this method makes the difficulty level of decryption more complex than the ordinary Hill Cipher, which only uses one key for all so that the security of the data obtained is also getting better.

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