National Cryptography Day in Indonesia Date in the current year: April 4, 2025

During the Dutch colonial era, no Indonesians were assigned to perform signal intelligence tasks by the colonial authorities. The development of modern signal intelligence and cryptography in Indonesia began during the Indonesian National Revolution.

In 1946, Minister of Information and Defense Amir Sjarifudding assigned Lieutenant Colonel Roebiono Kertopati to establish an Indonesian signal intelligence unit. Dr. Kertopati was a medical doctor serving in Section B of the Ministry of Defense (military intelligence department). Although he had no formal training in intelligence, signal intelligence or cryptography, he approached the assignment with enthusiasm and dedication. As a result, the Code Service was formally established on April 4, 1946.

Despite their lack of formal training, Dr. Kertopati and his assistants managed to develop their own cryptographic techniques and systems that proved effective and reliable for securing communications on the battlefield, in guerrilla warfare, and in clandestine negotiations between the revolutionary government of Indonesia, the Netherlands, and the United Nations.

In 1949, the Code Service was renamed the Crypto Bureau and placed under the Ministry of Defense. A few months later, however, it became directly subordinate to the Office of the Prime Minister of Indonesia. In 1972, the Crypto Bureau again received a new name, the National Crypto Agency (Lembaga Sandi Negara, commonly abbreviated as Lemsaneg).

The development of cyber security in Indonesia began in the 2010s with the establishment of the National Cyber Security Desk (later renamed the Cyber Information Defense and Security Desk) under the Coordinating Ministry for Political, Legal and Security Affairs, which consisted of representatives from various agencies and organizations. In addition, law enforcement, military, and intelligence agencies, as well as government ministries, had their own cyber security units.

In 2017, Indonesian President Joko Widodo merged the National Crypto Agency and the Cyber Information Defense and Security Desk to form a new agency responsible for signal intelligence, cyber intelligence, cyber defense, and cyber security. It was named the National Cyber and Crypto Agency (Badan Siber dan Sandi Negara, BSSN). It inherited the infrastructure and resources of the National Crypto Agency with the added responsibility of cyber security and intelligence.

National Cryptography Day is celebrated in Indonesia on April 4 to commemorate the establishment of the Code Service on this day in 1946, to highlight the role of Dr. Roebiono Kertopati as the father of Indonesian signal intelligence and cryptography, and to recognize the contribution of signal and cyber intelligence specialists to national defense.