1. The plaintiffs' appeals against the defendants and selective claims against the defendant C and D added in the trial.

1. The court's explanation concerning this case is the same as the statement of the judgment of the court of first instance except for the following parts written or added. As such, the court's explanation concerning this case shall be cited by the main sentence of Article 420 of the Civil Procedure Act.

【The part to be cited or added 【Defendant C Co., Ltd. (hereinafter “Defendant C”)’s “Defendant C”)” between the third through fourth of the judgment of the court of first instance.

The last 5th of the judgment of the first instance court shall be put into “C”.

Part 10 "13 billion won" shall be added to "1.3 billion won" under the sixth Table of the decision of the court of first instance.

The following shall be added to the seventh fifteenth sentence of the first instance court:

However, the fact that the instant security technology is not applied to K-voting service is one of the most important information required at the time of rational investment decision, and even if the F agreed with G institution not to apply the instant security technology, such agreement itself is also required for reasonable investment, Defendant C-D did not notify the Plaintiffs.

The following shall be added to the 8th sentence of the first instance court:

In addition, the Plaintiffs entered into the instant contract by mistake that the instant security technology is applied to the K-voting service, which is not gross negligence on the Plaintiffs as to the important parts of the terms and conditions of the contract, and even if the said mistake is the motive mistake, it was caused by Defendant C and D.

Therefore, the Plaintiffs, pursuant to Article 109 of the Civil Act, seek the payment of the said money due to the cancellation of the instant contract and the return of unjust enrichment from the cancellation of the contract to Defendant C and D.

Part 10 of the Decision of the Court of First Instance shall add to the following:

C. Meanwhile, F applied the security technology of this case to K-voting service without bearing expenses.