File Specification

Index file

• Path: /index
• Encrypted: yes (with user private key)

{
  "files": [
    {
      "id": "DOC_SHORT_HASH",
      "name": "image.jpg",
      "url": "UUID",
      "size": 1234567890,
      "content_type: "png",
      "created_at": "2008-03-01T13:00:00",
      "uploaded": true,
      "deleted": false,
      "num_parts": 2,
      "passcode": "encryption passcode that goes in the share link",
      "part_ivs": ["part0_IV_base64", "part1_IV_base64"],
      "username": "johnsmith.id.blockstack",
      "encryption": {
        "type": "PBKDF2/AES",
        "params": {
          "key_iterations": 10000,
          "salt": "abcdef12348",
          "iv": "1234n1234n123n12n1234=="
        }
      },
     "version": 2
    ...
  ]
}

Notes

• content_type is optional
• DOC_SHORT_HASH is 6 characters long and contains only [A-Za-z0-9]
• passcode is 16 characters long and contains only [A-Za-z0-9]
• All IVs are base64 encoded

Doc file

• Path: /DOC_SHORT_HASH
• Encrypted: no

{
  "encryption": {
    "type": "PBKDF2/AES",
    "params": {
      "key_iterations": 10000,
      "salt": "f98cnhd132",
      "iv": "5432n7542n754n78n7985=="
    }
  },
  "payload": "encrypted payload in base64"
}

Notes

• The encrypted payload contains a Doc object, following the same JSON format as an individual doc inside the index file

Raw file

• Path:
  • If file size smaller than the part size: UUID
  • If file size bigger than the part size, each part: UUID.partN
• Encrypted: yes (with the encryption, passcode and part_ivs specified in the doc file)
• Content-Type should always be application/octet-stream

Encryption

PBKDF2/AES

• Key generation algorithm: PBKDF2withHmacSHA256
• Key size: 256 bits
• Encryption algorithm: AES/CTR/NoPadding