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+# Data preparation
+
+This step consists in using an input directory, encrypt it and ship it to the supercomputing site, it's decryption key to the vault.
+
+## Sequence diagram of data preparation
+
+```mermaid
+sequenceDiagram
+    User -->> Data Preparation container: spawns using docker-compose
+    Data Preparation container -->> Spire Agent: spawns using `spawn_agent.py`
+    Spire Agent ->> Spire Server: Runs node attestation
+    Spire Server ->> Spire Agent: Attests node, provide SVIDs for linked identities
+    Data Preparation container ->> Data Preparation container: Prepare data, results in an encrypted tgz and a private key
+    Data Preparation container ->> Spire Agent: Fetches API to get an SVID
+    Spire Agent ->> Data Preparation container: Provides SVID
+    Data Preparation container ->> Vault: Log-in using SVID
+    Vault ->> Data Preparation container: Returns an authentication token (write only on client's path)
+    Data Preparation container ->> Vault: Write private key using authentication token
+    Vault ->> Data Preparation container: 
+    Data Preparation container ->> HPCS Server: Request creation of workloads (compute nodes, users, groups ...) authorized to access the key and using SVID to authenticate
+    HPCS Server ->> Spire Server: Validate SVID
+    Spire Server ->> HPCS Spire Agent: 
+    HPCS Spire Agent ->> Spire Server: Validate SVID
+    Spire Server ->> HPCS Server: 
+    HPCS Server ->> Spire Server: Create workloads identities to access the key
+    Spire Server ->> HPCS Server: 
+    HPCS Server ->> Vault: Create role and policy to access the key
+    Vault ->> HPCS Server: 
+    HPCS Server ->> Data Preparation container: SpiffeID & role to access the container, path to the secret
+    Data Preparation container ->> Data Preparation container: Parse info file based on previous steps
+    Data Preparation container ->> Supercomputer: Ship encrypted containe
+    Supercomputer ->> Data Preparation container: 
+    Data Preparation container ->> Supercomputer: Ship info file
+    Supercomputer ->> Data Preparation container: 
+    Data Preparation container -->> Spire Agent: Kills
+    Spire Agent -->> Data Preparation container: 
+    Spire Agent -->> Data Preparation container: Dies 
+    Data Preparation container -->> User: Finishes
+```
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