Crypt Db

[Vespasiano Jilg]

Originally, crypts were typically found below the main apse of a church, such as at the Abbey of Saint-Germain en Auxerre, but were later located beneath chancel, naves and transepts as well. Occasionally churches were raised high to accommodate a crypt at the ground level, such as St Michael's Church in Hildesheim, Germany.

The word "crypt" developed as an alternative form of the Latin "vault" as it was carried over into Late Latin, and came to refer to the ritual rooms found underneath church buildings. It also served as a vault for storing important and/or sacred items.

First known in the early Christian period, in particular North Africa at Chlef and Djemila in Algeria, and Byzantium at Saint John Studio in Constantinople where Christian churches have been built over mithraea, the mithraeum has often been adapted to serve as a crypt.

The famous crypt at Old St. Peter's Basilica, Rome, developed about the year 600, as a means of affording pilgrims a view of Saint Peter's tomb, which lay according to the Roman fashion, directly below the high altar. The tomb was made accessible through an underground passageway beneath the sanctuary from where pilgrims could enter at one stair, pass by the tomb and exit without interrupting the clerical community's service at the altar directly above.[1]

The Visigothic crypt (the Crypt of San Antoln) in Palencia Cathedral (Spain), was built during the reign of Wamba to preserve the remains of the martyr Saint Antoninus of Pamiers, a Visigothic-Gallic nobleman brought from Narbonne to Visigothic Hispania in 672 or 673 by Wamba himself. These are the only remains of the Visigothic cathedral of Palencia.[2]

Crypts were introduced into Frankish church building in the mid-8th century, as a feature of its Romanization. Their popularity then spread more widely in western Europe under Charlemagne. Examples from this period are most common in the early medieval West, for example in Burgundy at Dijon and Tournus.

After the 10th century, the early medieval requirements of a crypt faded, as church officials permitted relics to be held in the main level of the church. By the Gothic period crypts were rarely built, however burial vaults continued to be constructed beneath churches and referred to as crypts.

In more modern terms, a crypt is most often a stone chambered burial vault used to store the deceased. Placing a corpse into a crypt can be called immurement, and is a method of final disposition, as an alternative to, for example, cremation. Crypts are usually found in cemeteries and under public religious buildings, such as churches or cathedrals, but are also occasionally found beneath mausolea or chapels on personal estates. Wealthy or prestigious families will often have a 'family crypt' or 'vault,' in which all members of the family are interred. Many royal families, for example, have vast crypts containing the bodies of dozens of former royalty. In some localities, an above ground crypt is more commonly called a mausoleum, which also refers to any elaborate building intended as a burial place, for any number of people.

There was a trend in the 19th century of building crypts on medium to large size family estates, usually subtly placed on the edge of the grounds or more commonly incorporated into the cellar. After a change of owner, these are often blocked up and the house deeds will not allow this area to be re-developed [citation needed].

A remote of type crypt does not access a storage systemdirectly, but instead wraps another remote, which in turn accessesthe storage system. This is similar to how alias,union, chunkerand a few others work. It makes the usage very flexible, as you canadd a layer, in this case an encryption layer, on top of any otherbackend, even in multiple layers. Rclone's functionalitycan be used as with any other remote, for example you canmount a crypt remote.

Accessing a storage system through a crypt remote realizes client-sideencryption, which makes it safe to keep your data in a location you donot trust will not get compromised.When working against the crypt remote, rclone will automaticallyencrypt (before uploading) and decrypt (after downloading) on your localsystem as needed on the fly, leaving the data encrypted at rest in thewrapped remote. If you access the storage system using an applicationother than rclone, or access the wrapped remote directly using rclone,there will not be any encryption/decryption: Downloading existing contentwill just give you the encrypted (scrambled) format, and anything youupload will not become encrypted.

The encryption is a secret-key encryption (also called symmetric key encryption)algorithm, where a password (or pass phrase) is used to generate real encryption key.The password can be supplied by user, or you may chose to let rclonegenerate one. It will be stored in the configuration file, in a lightly obscured form.If you are in an environment where you are not able to keep your configurationsecured, you should addconfiguration encryptionas protection. As long as you have this configuration file, you will be able todecrypt your data. Without the configuration file, as long as you rememberthe password (or keep it in a safe place), you can re-create the configurationand gain access to the existing data. You may also configure a correspondingremote in a different installation to access the same data.See below for guidance to changing password.

Encryption uses cryptographic salt,to permute the encryption key so that the same string may be encrypted indifferent ways. When configuring the crypt remote it is optional to enter a salt,or to let rclone generate a unique salt. If omitted, rclone uses a built-in unique string.Normally in cryptography, the salt is stored together with the encrypted content,and do not have to be memorized by the user. This is not the case in rclone,because rclone does not store any additional information on the remotes. Use ofcustom salt is effectively a second password that must be memorized.

File content encryption is performed usingNaCl SecretBox,based on XSalsa20 cipher and Poly1305 for integrity.Names (file- and directory names) are also encryptedby default, but this has some implications and is thereforepossible to be turned off.

Before configuring the crypt remote, check the underlying remote isworking. In this example the underlying remote is called remote.We will configure a path path within this remote to contain theencrypted content. Anything inside remote:path will be encryptedand anything outside will not.

When you are done you can use the crypt remote named secret justas you would with any other remote, e.g. rclone copy D:\docs secret:\docs,and rclone will encrypt and decrypt as needed on the fly.If you access the wrapped remote remote:path directly you will bypassthe encryption, and anything you read will be in encrypted form, andanything you write will be unencrypted. To avoid issues it is best toconfigure a dedicated path for encrypted content, and access itexclusively through a crypt remote.

Important The crypt password stored in rclone.conf is lightlyobscured. That only protects it from cursory inspection. It is notsecure unless configuration encryption of rclone.conf is specified.

You may also specify a local filesystem path, such as/path/to/dir on Linux, C:\path\to\dir on Windows. By creatinga crypt remote pointing to such a local filesystem path, you canuse rclone as a utility for pure local file encryption, for exampleto keep encrypted files on a removable USB drive.

Note: A string which do not contain a : will by rclone be treatedas a relative path in the local filesystem. For example, if you enterthe name remote without the trailing :, it will be treated asa subdirectory of the current directory with name "remote".

If a path remote:path/to/dir is specified, rclone stores encryptedfiles in path/to/dir on the remote. With file name encryption, filessaved to secret:subdir/subfile are stored in the unencrypted pathpath/to/dir but the subdir/subpath element is encrypted.

If you intend to use the wrapped remote both directly for keepingunencrypted content, as well as through a crypt remote for encryptedcontent, it is recommended to point the crypt remote to a separatedirectory within the wrapped remote. If you use a bucket-based storagesystem (e.g. Swift, S3, Google Compute Storage, B2) it is generallyadvisable to wrap the crypt remote around a specific bucket (s3:bucket).If wrapping around the entire root of the storage (s3:), and use theoptional file name encryption, rclone will encrypt the bucket name.

Should the password, or the configuration file containing a lightly obscuredform of the password, be compromised, you need to re-encrypt your data witha new password. Since rclone uses secret-key encryption, where the encryptionkey is generated directly from the password kept on the client, it is notpossible to change the password/key of already encrypted content. Just changingthe password configured for an existing crypt remote means you will no longerable to decrypt any of the previously encrypted content. The only possibilityis to re-upload everything via a crypt remote configured with your new password.

This is a simple "rotate" of the filename, with each file having a rotdistance based on the filename. Rclone stores the distance at thebeginning of the filename. A file called "hello" may become "53.jgnnq".

Obfuscation is not a strong encryption of filenames, but hindersautomated scanning tools picking up on filename patterns. It is anintermediate between "off" and "standard" which allows for longer pathsegment names.

Cloud storage systems have limits on file name length andtotal path length which rclone is more likely to breach using"Standard" file name encryption. Where file names are 143 or fewercharacters in length issues should not be encountered, irrespective ofcloud storage provider.

An experimental advanced option filename_encoding is now provided toaddress this problem to a certain degree.For cloud storage systems with case sensitive file names (e.g. Google Drive),base64 can be used to reduce file name length.For cloud storage systems using UTF-16 to store file names internally(e.g. OneDrive, Dropbox, Box), base32768 can be used to drastically reducefile name length.

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