The SHA-256 algorithm is still quite popular in password encryption for website user account logins and digital signature encryption. The security of SHA-256 lies in using a one-way hash function that cannot return the message to its original form. However, there are currently many tools on the internet that provide SHA-256 message decryption services so that the original message is obtained. This is what causes the security level of SHA-256 to be less good. For this reason, experts have introduced several improvements to SHA-256. One researcher has modified SHA-256 by adding the Hill Cipher algorithm. This aims to produce a different message digest so that it is not easily described by the decryption provider tool. However, hacking by tools on the internet is still possible using the Hill Cipher algorithm. Using the inverse (reverse) of the key matrix in the Hill Cipher allows the ciphertext to be converted back into plaintext, so there is always a chance of hacking by finding the inverse of the key matrix. For this reason, this study proposes improvements to SHA-256 by adding Hill Cipher modifications. Researchers still use SHA-256 to produce a message digest in the early stages. Furthermore, the resulting message digest will be forwarded with a modification of the Hill Cipher with a singular matrix key (it does not have an inverse). The use of a singular key matrix will invalidate the opportunity for hacking through an inverse matrix attack. In the final stage, researchers will test the execution speed of the proposed system.