A digital signature is a type of asymmetric cryptography that is used to ensure that the recipient receives the actual received message from the intended sender. Problems that often arise conventionally when requiring letter approval from the authorized official, and the letter concerned is very important and urgent, often the process of giving the signature is hampered because the official concerned is not in place. With these obstacles, the letter that should be distributed immediately becomes hampered and takes a long time in terms of signing the letter. The purpose of this study is to overcome eavesdropping and data exchange in sending data using Digital Signature as authentication of data authenticity and minimizing fake signatures on letters that are not made and authorized by relevant officials based on digital signatures stored in the database. This research implements the Rivest Shamir Adleman method. (RSA) as outlined in an application to provide authorization or online signature with Digital Signature. The results of the study The application of the Rivest Shamir Adleman (RSA) algorithm can run on applications with the Digital Signature method based on ISO 9126 testing by expert examiners, and the questionnaire distributed to users and application operators obtained good results from an average value of 79.81 based on the scale table ISO 9126 conversion, the next recommendation for encryption does not use MD5 but uses Bcrypt secure database to make it stronger.

As the demand for effective information protection grows, security has become the primary concern in protecting such data from attackers. Cryptography is one of the methods for safeguarding such information. It is a method of storing and distributing data in a specific format that can only be read and processed by the intended recipient. It offers a variety of security services like integrity, authentication, confidentiality and non-repudiation, Malicious. Confidentiality service is required for preventing disclosure of information to unauthorized parties. In this paper, there are no ideal hash functions that dwell in digital signature concepts is proved.

This is the time of internet, and we are communicating our confidential data over internet in daily life. So, it is necessary to check the authenticity in communication to stop non-repudiation, of the sender. We are using the digital signature for stopping the non-repudiation. There are many versions of digital signature are available in the market. But in every algorithm, we are sending the original message and the digest message to the receiver. Hence, there is no security applied on the original message. In this paper we are proposed an algorithm which can secure the original and its integrity. In this paper we are using the RSA algorithm as the encryption and decryption algorithm, and SHA256 algorithm for making the hash.

The paper presents the concept of the association of digital signature technology with the currently trending blockchain technology for providing a mechanism which would detect any dubious data and store it in a place where it could be secure for the long term. The features of blockchain technology perfectly complement the requirements of the educational fields of today's world. The growing trend of digital certificate usage makes it easier for a dubious certificate to existing, among the others hampering the integrity of professional life. Association of hash key and a time stamp with a digital document would ensure that a third person does not corrupt the following certificate. The blockchain ensures that after verification, nobody else misuses the data uploaded and keeps it safe for a long time. The information from the blockchain can be retrieved at any moment by the user using the unique id associated with every user.

The rapid development of technology, makes it easier for everyone to exchange information and knowledge. Exchange information via the internet is threatened with security. Security issues, especially the issue of the confidentiality of information content and its authenticity, are vital things that must protect. Peculiarly for agencies that often hold activities that provide certificates in digital form to participants. Digital certificates are digital files conventionally used as proof of participation or a sign of appreciation owned by someone. We need a security technology for certificates as a source of information known as cryptography. This study aims to validate and authenticate digital certificates with digital signatures using SHA-256, DSA, and 3DES. The use of the SHA-256 hash function is in line with the DSA method and the implementation of 3DES which uses 2 private keys so that the security of digital certificate files can be increased. The pixel changes that appear in the MSE calculation have the lowest value of 7.4510 and the highest value of 165.0561 when the file is manipulated, it answers the security of the proposed method is maintained because the only valid file is the original file.