function proxyPayment(address participant) payable {
  // No contributions after the crowdsale is finalised
  require(!finalised);

  // No contributions before the start of the crowdsale
  require(now >= START_DATE);
  // No contributions after the end of the crowdsale
  require(now <= END_DATE);

  // No contributions below the minimum (can be 0 ETH)
  require(msg.value >= CONTRIBUTIONS_MIN);
  // No contributions above a maximum (if maximum is set to non-0)
  require(CONTRIBUTIONS_MAX == 0 || msg.value < CONTRIBUTIONS_MAX);

  // Calculate number of tokens for contributed ETH
  // `18` is the ETH decimals
  // `- decimals` is the token decimals
  // `+ 3` for the tokens per 1,000 ETH factor
  uint256 tokens = (msg.value * tokensPerKEther) /
    10**uint256(18 - decimals + 3);

  // Check if the hard cap will be exceeded
  require(totalSupply + tokens <= TOKENS_HARD_CAP);

  // Add tokens purchased to account's balance and total supply
  balances[participant] = balances[participant].add(tokens);
  totalSupply = totalSupply.add(tokens);

  // Log the tokens purchased
  Transfer(0x0, participant, tokens);
  TokensBought(
    participant,
    msg.value,
    this.balance,
    tokens,
    totalSupply,
    tokensPerKEther
  );

  // KYC verification required before participant can transfer the tokens
  kycRequired[participant] = true;

  // Transfer the contributed ethers to the crowdsale wallet
  if (!wallet.send(msg.value)) throw;
}