Encryption in the SFN: How to Secure Communication Between Financial Institutions

Encryption in the SFN (National Financial System) is one of the key mechanisms for protecting the electronic transmission of data between financial institutions and the systems that make up the National Financial System. 

In practice, security depends on a combination of encryption, digital signatures, certificates, key protection, and access controls, in accordance with the technical requirements established by the Central Bank of Brazil for the RSFN (National Financial System Network) and its various services.

In an environment where financial messages may represent orders, settlements, records, and other critical transactions, it is not enough simply to transmit the data: it is necessary to ensure that it remains secure, intact, and associated with the correct identity throughout the entire process.

What is encryption in SFN?

Encryption in the SFN refers to the set of mechanisms used to protect messages and files transmitted between participants in financial systems, thereby reducing the risk of interception, alteration, or misuse of information.

The RSFN is the communications infrastructure used for the exchange of information among authorized participants. Its operation is subject to specific technical requirements, including security, communications, and messaging documents published by the Central Bank.

Protection does not rely on a single technology. It involves different layers, such as:

• Data encryption;
• Digital signatures for messages and files;
• Digital certificates;
• Protection of private keys;
• Authentication and access control;
• Isolation of critical areas;
• Traceability of operations.

The SFN Security Manual itself defines concepts such as private key, public key, authenticity, and confidentiality, highlighting that the protection of cryptographic assets is an essential part of financial communication security.

Why is encryption essential for financial institutions?

Financial institutions process information that can have a direct impact on the movement of funds, the settlement of transactions, asset records, and the operation of financial services.

In this context, a failure to protect communications can compromise not only the confidentiality of the data, but also its integrity and authenticity.

Cryptography primarily contributes to four objectives:

Confidentiality: prevents intercepted information from being understood by unauthorized parties.

Integrity: Ensures that unauthorized changes to data during processing or transmission can be detected.

Authenticity: Enables verification of the origin of a message or file through certification and signature mechanisms.

Traceability: When combined with appropriate records and controls, it allows for the tracking of relevant events related to information processing.

Therefore, cryptographic security in the SFN should not be viewed merely as a technical step in the transmission process. It is an integral part of the operational reliability of financial systems.

How does communication protection work on the RSFN?

In simple terms, the process can be understood as a sequence of message preparation, protection, transmission, and validation.

First, the institution's application prepares the data that needs to be sent. Next, the security mechanisms apply the necessary cryptographic procedures, including signing and encryption, depending on the protocol and service used.

The secured packet is then routed via the communication medium defined by the institution's architecture.

At the destination, the process is reversed: the security mechanisms validate the message, verify the signature, and decrypt it when applicable, allowing the recipient application to process the content.

In PRODIST solutions designed for SFN, this process includes preparing the SFN packet, encryption, signing, and the security header. The solution can also perform the reverse process—decryption and signature verification.

This separation is important because it means that business applications do not have to individually implement all the cryptographic logic required for each communication.

What are the main security requirements for communication in the SFN?

Requirements vary depending on the system and service used. Therefore, the institution must always refer to the Central Bank’s current technical documentation, including the SFN Service Catalog and the applicable Security and Network Manuals. The Central Bank’s (BCB) official electronic communications page provides the current versions of these documents.

Among the key points to note are:

Protection of Private Keys

The private key is one of the most sensitive assets in a cryptographic infrastructure. If it is compromised, a third party could perform operations that should be restricted to the institution.

Therefore, controlling physical and logical access to keys, protecting them, and preventing their improper sharing are important elements of the security policy. Current regulations also establish requirements regarding the safekeeping and control of private keys.

Digital Certificate Management

Certificates are used to establish cryptographic identities and support authentication and signature mechanisms.

The SFN infrastructure itself has specific requirements for digital certificates, and the Central Bank maintains information on certification authorities and technical documents applicable to the RSFN.

In addition, updating certificates is an operational activity that must be monitored. In July 2026, for example, the Central Bank announced the update of certificates used in the messaging systems of certain RSFN domains.

Insulation of Critical Environments

Physical and logical isolation is another important layer of protection.

The current rules reinforce specific requirements for environments related to Pix and the Reserve Transfer System (STR), including the isolation of these environments and administrative access controls.

This type of control reduces the likelihood that a compromise in another part of the organization will directly affect the systems used in critical operations.

Authentication and Access Control

Cryptographic protection must be accompanied by mechanisms that restrict who can access systems, certificates, keys, and administrative functions.

This means applying the principle of least privilege, separating responsibilities, and strictly controlling the credentials used by the components involved in communication.

What has changed in SFN's cybersecurity?

The ongoing digitization of the financial system has increased the importance of cybersecurity controls.

In December 2025, the Central Bank and the National Monetary Council approved new requirements related to cybersecurity policy and the procurement of processing, storage, and cloud computing services.

Among the points highlighted by the BCB are digital certificate management, secure system integration, traceability, access controls, network protection, and additional requirements for communication with the RSFN.

The regulation also strengthened requirements related to electronic data reporting in the RSFN, including additional controls for Pix and STR environments and the protection of institutions’ private keys.

For organizations, this means that communication security must be addressed as an integral part of technology governance, risk management, and business continuity.

What are the challenges of cryptography in the SFN?

Implementing cryptographic mechanisms in financial environments involves challenges that go beyond simply choosing an algorithm.

Among the main ones are:

• Manage multiple keys and certificates;
• Control access to private keys;
• Track certificate validity and replacement;
• Keep production and validation environments properly separated;
• Integrate different applications and programming languages;
• Monitor changes in technical standards;
• Maintain traceability of operations;
• Ensure the availability of cryptographic components;
• Prevent specific knowledge from being concentrated among just a few professionals;
• Respond quickly to incidents or operational failures.

The complexity increases when different systems need to communicate with various services provided by BACEN and NÚCLEA.

In this scenario, a specialized solution can reduce the need to develop and maintain specific cryptographic components in-house, allowing the technology team to focus its efforts on the application and the business.

How does PRODIST help protect communications on the SFN?

PRODIST STS offers a specialized solution for financial institutions that need to implement secure communication based on SFN requirements, with options for on-premises or cloud-based architectures.

The solution can receive the data prepared by the application and perform the SFN packet preparation process, including encryption, signing, and the security header. 

The package can then be shipped to its destination via the mode of transportation specified by the institution. Upon receipt, the solution performs the reading process, including decryption and signature validation.

This model allows cryptographic functions to be separated from business applications, creating a specialized layer for message protection and processing.

What does PRODIST STS offer?

Among its key capabilities are:

• Packaging of messages and files;
• Validation of security packages;
• Message encryption and signing;
• Integration by component, file system, or microservice;
• OAuth2 access control;
• On-premises or cloud-based architecture;
• Cryptographic key protection and management;
• Integration with HSMs from approved partners;
• Integration with cloud-based Vaults and KMS;
• Role-Based Access Control (RBAC);
• mTLS authentication;
• Remote management.

Why use a specialized encryption solution on the SFN?

For financial institutions, the main advantage lies in consolidating highly specialized functions into a dedicated technology layer.

Instead of each application individually implementing encryption, signing, certificates, and key protection mechanisms, the organization can use specialized components and integrate them into existing systems.

This may contribute to:

• Greater standardization of cryptographic processes;
• Reduced integration complexity;
• Greater control over keys and certificates;
• Ease of maintenance;
• Traceability;
• Compliance with applicable technical requirements;
• Greater operational predictability;
• Reduced reliance on in-house cryptographic implementations.

The choice of architecture, however, must take into account the specific requirements of the service, the technological environment, and the institution’s own security policies.

PRODIST: Expertise in Cryptography and Security for the Financial Market

Founded in 1987, PRODIST specializes in developing encryption and digital security solutions for financial transactions. Our solutions have been in operation since the launch of the Brazilian Payment System in 2002 and serve more than 40 financial institutions.

Our portfolio includes solutions for the SFN, BACEN, NÚCLEA, Pix, and SPED ecosystems, with a focus on organizations that need to combine cryptographic security, regulatory compliance, availability, and technological integration.

For institutions that need to implement or modernize their encryption infrastructure for communication with SFN systems, PRODIST can support the project from the initial assessment of the current situation and definition of the architecture through to deployment and ongoing support.

Talk to a PRODIST specialist to assess the technical requirements of your environment and identify the most appropriate architecture to secure your communications on the SFN.

FAQ – Encryption in SFN