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97 lines
No EOL
4.1 KiB
Text
97 lines
No EOL
4.1 KiB
Text
@startuml grin-transaction
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title
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**Current Grin Tranaction Workflow**
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Accurate as of Aug 1, 2018 - Master branch only
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end title
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actor "Sender" as sender
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actor "Recipient" as recipient
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entity "Grin Node" as grin_node
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== Round 1 ==
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note left of sender
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1: Create Transaction **UUID** (for reference and maintaining correct state)
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2: Set **lock_height** for transaction kernel (current chain height)
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3: Select **inputs** using desired selection strategy
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4: Calculate sum **inputs** blinding factors **xI**
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5: Create **change_output**
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6: Select blinding factor **xC** for **change_output**
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7: Create lock function **sF** that locks **inputs** and stores **change_output** in wallet
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and identifying wallet transaction log entry **TS** linking **inputs + outputs**
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(Not executed at this point)
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end note
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note left of sender
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8: Calculate **tx_weight**: MAX(-1 * **num_inputs** + 4 * (**num_change_outputs** + 1), 1)
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(+1 covers a single output on the receiver's side)
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9: Calculate **fee**: **tx_weight** * 1_000_000 nG
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10: Calculate total blinding excess sum for all inputs and outputs **xS1** = **xC** - **xI** (private scalar)
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11: Select a random nonce **kS** (private scalar)
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12: Subtract random kernel offset **oS** from **xS1**. Calculate **xS** = **xS1** - **oS**
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13: Multiply **xS** and **kS** by generator G to create public curve points **xSG** and **kSG**
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14: Add values to **Slate** for passing to other participants: **UUID, inputs, change_outputs,**
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**fee, amount, lock_height, kSG, xSG, oS**
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end note
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sender -> recipient: **Slate**
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== Round 2 ==
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note right of recipient
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1: Check fee against number of **inputs**, **change_outputs** +1 * **receiver_output**)
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2: Create **receiver_output**
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3: Choose random blinding factor for **receiver_output** **xR** (private scalar)
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end note
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note right of recipient
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4: Calculate message **M** = **fee | lock_height **
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5: Choose random nonce **kR** (private scalar)
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6: Multiply **xR** and **kR** by generator G to create public curve points **xRG** and **kRG**
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7: Compute Schnorr challenge **e** = SHA256(**M** | **kRG** + **kSG**)
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8: Compute Recipient Schnorr signature **sR** = **kR** + **e** * **xR**
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9: Add **sR, xRG, kRG** to **Slate**
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10: Create wallet output function **rF** that stores **receiver_output** in wallet with status "Unconfirmed"
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and identifying transaction log entry **TR** linking **receiver_output** with transaction.
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end note
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alt All Okay
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recipient --> sender: Okay - **Slate**
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recipient -> recipient: execute wallet output function **rF**
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else Any Failure
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recipient ->x]: Abort
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recipient --> sender: Error
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[x<- sender: Abort
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end
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== Finalize Transaction ==
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note left of sender
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1: Calculate message **M** = **fee | lock_height **
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2: Compute Schnorr challenge **e** = SHA256(**M** | **kRG** + **kSG**)
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3: Verify **sR** by verifying **kRG** + **e** * **xRG** = **sRG**
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4: Compute Sender Schnorr signature **sS** = **kS** + **e** * **xS**
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5: Calculate final signature **s** = (**sS**+**sR**, **kSG**+**kRG**)
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6: Calculate public key for **s**: **xG** = **xRG** + **xSG**
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7: Verify **s** against excess values in final transaction using **xG**
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8: Create Transaction Kernel Containing:
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Excess signature **s**
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Public excess **xG**
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**fee**
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**lock_height**
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end note
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sender -> sender: Create final transaction **tx** from **Slate**
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sender -> grin_node: Post **tx** to mempool
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grin_node --> recipient: "Ok"
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alt All Okay
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recipient --> sender: "Ok" - **UUID**
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sender -> sender: Execute wallet lock function **sF**
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...Await confirmation...
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recipient -> grin_node: Confirm **receiver_output**
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recipient -> recipient: Change status of **receiver_output** to "Confirmed"
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sender -> grin_node: Confirm **change_output**
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sender -> sender: Change status of **inputs** to "Spent"
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sender -> sender: Change status of **change_output** to "Confirmed"
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else Any Error
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recipient -> recipient: Manually remove **receiver_output** from wallet using transaction log entry **TR**
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recipient ->x]: Abort
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recipient --> sender: Error
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sender -> sender: Unlock **inputs** and delete **change_output** identified in transaction log entry **TS**
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[x<- sender: Abort
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end
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@enduml |