Matching Tokens between Client and Server

 Matching Tokens between Client and Server (vault)

When a token is generated at the source (such as an ATM or point-of-sale terminal) and needs to be matched with the original data stored in a central token vault, several processes ensure that the token can be mapped back to its original sensitive data. Here’s how the matching process works:

1. Token Generation at Source

When sensitive data (e.g., a card number) is entered at the source, the following happens:

• Tokenization Algorithm: The sensitive data is passed through a tokenization algorithm. The algorithm may use one or more of the following methods:

  • Random Token Generation: A completely random string is generated to represent the sensitive data.
  • Deterministic Token Generation: A tokenization algorithm that produces the same token each time the same input data is provided. This ensures that for a given piece of sensitive data (e.g., a specific card number), the same token is generated every time.

  The choice between these two methods depends on the use case. Random token generation enhances security, while deterministic tokens may be preferred for systems where repeated references to the same token need to be mapped.

• Secure Transmission: The token is then transmitted to the central server (bank or payment processor) for processing. Sensitive data is never sent over the network, only the token.

2. Token Vault in Central System

The central token vault plays a critical role in the mapping process. Here’s how it works:

• Mapping Sensitive Data to Tokens:

  • When the sensitive data is first tokenized, the original sensitive data (e.g., the card number) and the corresponding token are stored securely in the token vault. This is usually stored in a database that ensures secure, encrypted storage of both tokens and sensitive data.
  • Each token has a unique mapping to the original sensitive data in the vault. This relationship is stored in a secure environment, isolated from external access.

• Unique Identifier for Each Token:

  • The token vault uses the token as a unique identifier to find the corresponding sensitive data. The token is a key in the database that points to the original data.
  • In some cases, metadata about the transaction (such as timestamps or transaction details) may also be associated with the token to help with auditing or processing.

3. Matching the Token with the Original Data

Once a token reaches the central server, the following occurs:

• Token Query:
  • The system sends the received token to the token vault to retrieve the corresponding sensitive data. The token vault receives the token as an input and performs a lookup in its secure database.
• Token-to-Data Mapping:
  • If the token was generated using a randomized tokenization method, the token vault uses a direct lookup. The vault will search for the token and return the associated sensitive data (e.g., PAN or card number) from the database.
  • If deterministic tokenization is used, the vault can also perform a direct lookup. However, deterministic tokens allow for faster matching in cases where repeated use of the same token is required (for example, recurring payments or multi-step transaction processing).
• Decryption and Retrieval:
  • In most cases, sensitive data stored in the vault is encrypted. The token vault decrypts the sensitive data before returning it to the server for processing.
  • The sensitive data is then used by the central system (bank, payment processor, etc.) to perform the actual transaction (e.g., debiting the account associated with the card number).

4. Security Measures for Token Mapping

Several security measures are in place to ensure that the tokenization process is secure and that tokens are correctly matched with the original data:

• Encryption:
  • The sensitive data stored in the token vault is encrypted, typically using strong encryption algorithms like AES-256. Even if the vault is compromised, the original data remains secure.
• Access Control:
  • Only authorized systems and personnel have access to the token vault. This is enforced using multi-factor authentication (MFA), access control lists (ACLs), and role-based access control (RBAC).
• Secure Communications:
  • The communication between the source (ATM or POS terminal) and the token vault uses secure channels (e.g., TLS) to prevent interception or tampering during transmission.
• Token Vault Isolation:
  • The token vault is often housed in a highly secure environment, separate from the systems that process transactions. This limits the exposure of sensitive data and reduces the risk of unauthorized access.

5. Examples of Matching Token with Original Data

To better understand the token-to-data matching process, let’s look at two examples:

Example 1: Random Token Generation

• At the Source: The user swipes their card at an ATM. The ATM’s tokenization software generates a random token, such as TKN-XYZ123.
• In the Vault: In the token vault, the token TKN-XYZ123 is mapped to the original card number, such as 4111 1111 1111 1111.
• Transaction Processing: When the token is sent to the central server for transaction processing, the server queries the token vault with TKN-XYZ123. The vault looks up the token and retrieves the corresponding card number for processing.

Example 2: Deterministic Token Generation

• At the Source: The same user uses the same card at an ATM multiple times. Each time, the tokenization algorithm produces the same token, such as TKN-ABC456, for that card number.
• In the Vault: The token vault contains the mapping for TKN-ABC456 to the original card number. This allows the system to process repeated transactions efficiently, without needing to generate a new token for each transaction.

6. Key Differences Between Random and Deterministic Tokens

• Random Tokens:
  • Use Case: One-time or single-use transactions, such as ATM withdrawals.
  • Advantage: Higher security because the token cannot be reused or predicted.
  • Challenge: Token mapping must be performed for every transaction since tokens are unique.
• Deterministic Tokens:
  • Use Case: Recurring payments, subscriptions, or multi-step transaction processing.
  • Advantage: Consistent token for repeated use of the same data, reducing the need for frequent token vault lookups.
  • Challenge: Requires strong algorithms to ensure that tokens cannot be predicted or reverse-engineered.

Conclusion

The tokenization process at the source ensures that sensitive data is never exposed during transmission. Once the token is generated, it is sent to a central token vault, where it is securely mapped to the original sensitive data. Depending on the type of tokenization (random or deterministic), the token vault performs a direct lookup and provides the central server with the necessary sensitive data for transaction processing.

The key to matching tokens with the original data lies in the token vault, a highly secure and isolated system that stores the mapping between tokens and sensitive data. This ensures that even if tokens are intercepted, they are meaningless without access to the vault, providing a strong layer of security in tokenization systems.

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