QRL Address Scheme
QRL uses an extensible stateful asymmetrical hypertree signature scheme composed of chained XMSS trees.
This has the dual benefit of utilizing a validated signature scheme and allowing generation of ledger addresses with the ability to sign transactions avoiding a lengthy pre-computation delay seen with giant XMSS constructions. W-OTS+ is the chosen hash-based one-time signature in the scheme for both security and performance reasons.
Public Address Structure
A QRL address is designed to be extensible and supports a wide range of formats.
The first three bytes of any address (descriptor) encode information to describe the hash function, signature scheme, address format, and additional parameters.
A typical account address is represented as follows:
Q01070050d31c7f123995f097bc98209e9231d663dc26e06085df55dc2f6afe3c2cd62e8271a6bd
QRL Addresses are structured in the following way:
| Name | Bytes | Count | Description |
|---|---|---|---|
| DESC | 0 .. 2 | 3 | Address Descriptor |
| DATA | 3 .. N | ?? | N will depend on the address format |
Using sha256 2X, a QRL address is composed of 39 bytes. This is the internal format used by any API or module in the project.
At the moment, only one address format is utilized, sha256 2X, however we support crypto-agility and the ability to later move to new hash schemes as the security landscape changes.
For representational purposes (i.e. user interface, debugging, logs), it is possible that the address is represented as a hex-string prefixed with Q (79 hexadecimal characters). This is appropriate for user related purposes but will be rejected by the API
| Name | Bits | Count | Description |
|---|---|---|---|
| DESC | 0 .. 2 | 3 | Hash Function |
| HASH | 3 .. 35 | 32 | SHA2 256(DESC+PK) |
| VERH | 36 .. 40 | 4 | SHA2 256(DESC+HASH) (only last 4 bytes) |
In pythonic pseudocode this is represented as follows:
Address Descriptor
| Name | Bits | Count | Description |
|---|---|---|---|
| HF | 0 .. 3 | 4 | Hash Function |
| SIG | 4 .. 7 | 4 | Signature Scheme |
| P1 | 8 .. 11 | 4 | Parameters 1 (ie. height, etc.) |
| P2 | 12 .. 15 | 4 | Address Format |
| P3 | 16 .. 23 | 8 | Parameters 2 |
In the case of using XMSS, the parameters are used as follows:
| Name | Bits | Count | Description |
|---|---|---|---|
| HF | 0 .. 3 | 4 | SHA2-256, SHAKE128, SHAKE256 |
| SIG | 4 .. 7 | 4 | XMSS |
| P1 | 8 .. 11 | 4 | XMSS Height / 2 |
| AF | / P2 12 | . | . 15 4 Address Format |
| P3 | 16 .. 23 | 8 | Not used |
SIG - Signature Type
| Value | Description |
|---|---|
| 0 | XMSS |
| 1 .. 15 | Reserved - Future expansion |
HF - Hash Function
| Value | Description |
|---|---|
| 0 | SHA2 256 |
| 1 | SHAKE 128 |
| 2 | SHAKE 256 |
| 3 .. 15 | Reserved - Future expansion |
AF - Address Format
| Value | Description |
|---|---|
| 0 | SHA256 2X |
| 1 .. 15 | Reserved - Future expansion |