key
The 'key' directive specifies the HMAC key used for generating secure tokens for requests in the Secure Token module for NGINX.
Description
The 'key' directive in the Secure Token module for NGINX is essential for generating secure content delivery tokens, specifically when integrating with CDNs like Akamai and CloudFront. By specifying a hex-encoded string that represents the key, the server can create HMAC (Hash-based Message Authentication Code) values that ensure the integrity and authenticity of the tokens. These tokens can be included as query string parameters or cookies, allowing clients to authenticate access to protected resources based on time-limited and secure tokens.
When setting the 'key' directive, it's important to use a strong key that is not easily guessable, as it directly influences the security of the generated tokens. The key works in conjunction with parameters such as expiration time and ACL (Access Control List), each of which adds layers of security and control over resource access. The HMAC is computed using the SHA-256 hashing algorithm, ensuring a high level of security, as it requires the original key to validate the token's integrity against tampering attempts.
Setting the 'key' is mandatory, as the module cannot generate valid tokens without it. In the backend, this key will be used to compute the HMAC for the token, ultimately providing a secure method of resource access control. If the key is not set properly, clients may be denied access even if they provide valid tokens due to signature mismatches.
Config Example
secure_token_akamai {
key 0123456789abcdef0123456789abcdef;
acl "allow all";
start 1h;
end 2h;
param_name "token";
}Ensure the key is sufficiently long and complex to prevent brute-force attacks.
The key must be provided in a hexadecimal format; improper formatting could lead to errors in token generation.
Changes to the key require re-distributing tokens, as previously issued tokens will become invalid if the key changes.