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SSharing is secret sharing software that uses the (k, n) threshold secret sharing method.
Secret sharing is one of the cryptographic techniques, but it is different from the password-based cryptography used by many people in recent years. First, let's introduce the secret sharing method.
- Principle of (k, n) threshold secret sharing scheme
- Why secret sharing was not used
The principle of the (k, n) threshold secret sharing method is based on the following paper. Also known as Shamir's secret sharing.
"How to Share a Secret", Adi Shamir, Massachusetts Institute of Technology Communications of the ACM November 1979, Volume 22, Number 11
The following polynomials are set as the threshold value and the number of shares.
When 
At the time of encoding,
is regarded as confidential information,
are randomly selected, and the
value and
are shared. At the time of decoding, the
value and
are collected, and the simultaneous polynomials are solved to obtain
.
The most popular cryptography today requires a password. Using only the same password will reduce confidentiality. But you can't remember so many passwords. If you change your password each time, you must write it down somewhere. Then, the next step is to manage the password.
(k, n) Threshold secret sharing method does not use passwords. This frees you from the hassle of managing passwords.
Compared to password encryption, (k, n) threshold secret sharing is much more confidential. In the case of password encryption, even people who do not know the password can search for the password with time and effort. If the information is leaked, someone may match and decrypt the password, even if it is encrypted. If someone tries to enter the password in a brute force manner, it may eventually match. That anxiety always accompanies us.
However, (k, n) threshold secret sharing cannot reconstruct the original information from some information. (k, n) Threshold secret sharing cannot be decrypted without sufficient information. Therefore, even if a part of the shared data is leaked, it is impossible to reconstruct the original information from the part of the information.
Secret sharing achieves not only high confidentiality but also high credibility at the same time. It is important to store information in multiple locations. If there is only one storage location and the information is corrupted, we will lose all the information. In the present age when a huge amount of work is computerized, the loss of that information brings about a serious situation. To handle information, it is essential to have the credibility of maintaining that information.
On the other hand, storing information in multiple locations increases the risk of information leakage. Even if you want to distribute the storage locations so that you do not have to worry if the information is damaged, the more you distribute it, the higher the risk of leakage. Increasing credibility reduces confidentiality. That is the reality of password encryption. It is not possible to achieve both the improvement of credibility and the improvement of confidentiality.
However, (k, n) threshold secret sharing improves confidentiality and credibility at the same time. Sharing is also encryption, so sharing will increase credibility and confidentiality. Let's disperse more and improve both confidentiality and credibility.
Some people have used (k, n) threshold secret sharing to manage confidential information such as storing the password itself. However, it is rarely popular in the public. Why didn't so many people use (k, n) threshold secret sharing? The reason was that it required a lot of storage space, and the processing time was long.
Storage capacity
(k, n) Threshold secret sharing "shares" information rather than "splits" it. In the case of "split", if you divide it into 10 pieces, the amount of each divided information will be 1/10. However, if you share to 10 pieces with (k, n) threshold secret sharing, the amount of each shared information does not change. Since it will increase to 10 files, the total amount of information will be 10 times. It may be easier to imagine if you say that you dilute the information in 10 times.
SSharing used the compression function. Also, storage media are becoming much cheaper these days. It requires more storage capacity than ever before, but it's not too expensive for high confidentiality and credibility.
Processing time
It takes time to compute (k, n) threshold secret sharing polynomial. If you take a day and don't complete the sharing process, it's not practical. However, the development of computers is remarkable. The calculation speed has also increased.
At SSharing, we worked on further speeding up the processing. We are maximizing the latest high-speed technology. If the Number of Shares is about several tens, you will not feel any stress even if you incorporate it into your daily work such as sending information and backing up.
SSharing uses this (k, n) threshold secret sharing method to share and encrypt information. You can achieve higher credibility than higher confidentiality than ever before. And you can achieve it with the same effort as before. The value of information increases day by day. There is also a growing demand for the secure storage of large amount of information. Build a safer information society by raising the information management method one step. SSharing aimed at that first step.
