Programmable Envelopes
Programmable envelopes contain predefined fields to allow different types of messages to be sent according to specific use case requirements. Mailchain is flexible and extensible, adding a messaging layer to blockchain protocols, supporting different types of messages to be sent. Blockchain protocols typically allow sending data as a byte array, which is efficient but not descriptive. Programmable Envelopes allow descriptive implementations of messaging use cases that can be encoded to a byte array.
Each envelope is implemented as code, describing the encoding method, fields, and interface functions.
Programmable Envelopes are preferred over adding optional fields. They remove some of the complexity, the need for additional documentation, are extensible in a modular sense, and create an improved developer experience.
Backwards and forwards compatibility can be achieved by never modifying an envelope after deployment.
Each envelope is required to implement a data interface. It will have different combinations of data fields to return a valid response for each of these methods. This interface is defined as:
type Data interface {URL(decrypter cipher.Decrypter) (url *url.URL, err error)IntegrityHash(decrypter cipher.Decrypter) (hash []byte, err error)ContentsHash(decrypter cipher.Decrypter) (hash []byte, err error)Valid() error}
Addressable location of the message, the URL may be encrypted requiring decrypter to be supplied to decrypt URL.
Parameters:
Name | Type | Notes |
decrypter | ​cipher.decrypter​ | Used to decrypt the URL where the message can be found. Decrypter is required but is only used if the url is stored encrypted. |
Returns:
Name | Type | Notes |
url | ​*url.URL​ | Address of the message. Nil if error. |
err | error | Error object describing the cause. |
Hash of the encrypted content. This can be used to validate the integrity of the envelope contents before decrypting.
Parameters:
Name | Type | Notes |
decrypter | ​cipher.decrypter​ | Used to decrypt the hash, where only the intended recipient can validate the contents. Decrypter is required but is only used if the hash is stored encrypted. |
Returns:
Name | Type | Notes |
hash | ​[]byte​ | Hash of the contents to validate integrity. Nil if error. |
err | error | Error object describing the cause. |
Integrity Hash is not intended to be cryptographically secure, use ContentsHash for a secure cryptographic hash.
Hash of the decrypted content. This can be used to verify the contents of the message have not been tampered with.
Parameters:
Name | Type | Notes |
decrypter | ​cipher.decrypter​ | Used to decrypt the hash, where only the intended recipient can verify the contents. Decrypter is required but is only used if the hash is stored encrypted. |
Returns:
Name | Type | Notes |
hash | ​[]byte​ | Hash of the contents to validate the message contents. Nil if error. |
err | error | Error object describing the cause. |
The first byte will describe the envelope implementation and encoding method used.
Byte Value | Notes |
| Reserved for unset value |
| |
| ​Alpha envelope​ |
| Reserved to extend beyond 255 envelope definitions |
While Protocol buffers are used by the first implemented envelopes, this is not a requirement. Each envelope describes it encoding method in the definition.
Zero value is reserved to identify that it has not been set and should be treated like an unset envelope identifier.
Is optimized for secure, verifiable messaging with minimal bytes, URL and ContentsHash are encrypted with a publicly verified IntegrityHash. 0x01 uses MLI to reduce the bytes needed to store the URL, the IntegrityHash is optional reducing the required number of bytes.
​Protocol buffers are used to define the structure of this message. This is the proto3 spec.
// Use hosted location where the decryptedhash is the same as the location. Location, decrypted hash are encrypted so only receipient can location and verify the message.message ZeroX01 {bytes UIBEncryptedLocationHash = 1;bytes encryptedHash = 2;}
Fields
Name | Type | Notes |
UIBEncryptedLocationHash | bytes | Required - Bytes are stored are represented with UInt64Bytes. |
encryptedHash | bytes | Optional - Bytes of hash |
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