02/07/2021

Easily send large encrypted files, and keep the key !

Cryptography

What is data, file or message encryption?

In cryptography, encryption (sometimes mistakenly called ciphering) is an operation that consists in transforming a message to be transmitted, called the "plaintext message", into another message, unintelligible to a third party, called the "encrypted message", in order to ensure the secrecy of its transmission to a recipient who would possess the (de)encryption key.

The main purpose of encryption is therefore to guarantee the confidentiality of digital data stored on computer systems or transmitted via the Internet or other networks. This information can include anything from payment data to personal information to health data.

The principles of encryption are based on the notion of encryption algorithms and "keys".The security of an encryption system is based on the secrecy of the encryption key, not the algorithm. Indeed, the Kerckhoffs principle assumes that the person who wants to decrypt the coded message knows the algorithm used.

Encryption is a primary technique used for data security, and it is the simplest and most important way to ensure that information in a computer system cannot be stolen and read by someone who would like to use it for malicious purposes.

Beyond the obvious need to protect private information from theft or threat, encryption also provides security for the following:

  • Authentication : can be used to prove that the information is authentic and comes from the source from which it claims to come.

  • Integrity : It can be used to prove that the content of a message has not been modified since it was sent.

  • Non-repudiation : allows to verify the origin of a message and to prevent the sender of a message to deny having sent this message.

The term "encryption" would be an Anglicism, taken from the English word encryption, itself coming from the Greek kryptô (hidden). In French, the word chiffrement should be used. The French Academy has specified that the word "cryptage" is to be banned and that it does not appear in its dictionary even if it is commonly used.

 

 

Symmetric Crypto

What is symmetric or asymmetric cryptography?

An encryption system is called symmetric when it uses the same key to encrypt and decrypt data.

Asymmetric encryption uses a public/private key pair, which allows to encrypt (with the public key) and decrypt (with the private key) data. The public key cannot be used to decrypt the data, and the private key cannot be deduced from the public key.

In an exchange between two people, the receiver can provide his public key to the sender to allow him to encrypt the data before sending it to him, and then the receiver can decrypt the data using his private key, which only he has.

The use of either of these types of encryption is conditioned by the end use. For example, symmetric encryption is commonly used to encrypt files. The longer the encryption key, the more computationally intensive the encryption/decryption steps will be on large files. Asymmetric encryption eliminates the problem of secure key transmission, and allows electronic signatures. However, it does not replace symmetric systems, as its computation times are much longer and asymmetric cryptography is more vulnerable to attacks by nature.

That's why, at Secrecy.me, we use symmetric cryptography to encrypt your data, and asymmetric cryptography to allow you to send the key to the recipient of your choice, without the need for a trusted third party. We also offer you the best compromise between security and computing time.

 

 

Services

 Looking for a service equivalent to wetransfer but encrypted ?

Wetransferring is in vogue, and allows you to send large files easily, but the files sent are not encrypted on your device. However, to protect data and make sure that it cannot be read by anyone other than the recipient, nothing is better than encrypting a file with the recipient's public key before sending it over the network.

This is what Secrecy.me offers, the first interoperable encryption service, allowing free encrypted cloud storage up to 15 GB of usage, and allowing its users to keep their private key on their machine to decrypt messages and files sent to them.

Unlike we transfer, Secrecy.me allows both storage of encrypted files, but also sending large encrypted files without the need for a trusted third party.

 

 

Difference

What is the difference between Secrecy and other online crypto services ?

In most of the other existing services, the private key that allows the data to be decrypted is entrusted to a "trusted third party" (usually a company), whose choice is generally determined at the outset by the platform offering the service. There is thus a theoretical risk in case of collusion between the host of the encrypted files and the trusted third party who would bring the key allowing to decrypt them.

With Secrecy.me the user keeps his private key on his computer, tablet or phone, and there is no need for this imposed trusted third party. However, the user can also entrust his key, or a part of it, to a trusted third party (a natural person such as a notary, a relative, or a legal person such as a company or an association) of his choice. This can be done in paper or electronic form, at the user's choice.