appsecret_proof.rs

extern crate rust_sodium;

use rust_sodium::crypto::auth::hmacsha256;

pub mod crypto {
  #[derive(Debug)]
  pub enum ErrType {
    BadKey,
  }

  //
  // Generate APPSECRET_PROOF, test for Facebook API
  //
  // # Arguments:
  //  * `key` - Key for secret proof
  //  * `data` - Data
  // # Return
  //  * Result<String, ErrType>
  //
  pub fn generate_appsecret_proof(key: &str, data: &str) -> Result<String, ErrType> {
    let auth_key = ::hmacsha256::Key::from_slice(key.as_bytes());

    match auth_key {
      Some(k) => {
        let tag = ::hmacsha256::authenticate(data.as_bytes(), &k);
        let str_data = tag.as_ref()
          .iter()
          .map(|v| -> String {
              let mut hex = format!("{:x}", v);
              if hex.len() == 1 {
                hex.insert(0, '0');
              }
              return hex;
            })
          .fold("".to_string(), |acc, x| acc + x.as_str());
        Ok(str_data)
      },
      None => Err(ErrType::BadKey)
    }
  }
}