Mapped Anchor

Mapped Anchoring stores hashes as key / value pairs on the blockchain.

The mapped anchor transaction is part of the Titanium release.

JSON

{
  "type": 22,
  "version": 3,
  "id": "Ebq8DzaxstCL3iuuh1ByAiNEEbTRZ5T4ZzFMM4KNWdh9",
  "sender": "3NBcx7AQqDopBj3WfwCVARNYuZyt1L9xEVM",
  "senderKeyType": "ed25519",
  "senderPublicKey": "7gghhSwKRvshZwwh6sG97mzo1qoFtHEQK7iM4vGcnEt7",
  "fee": 45000000,
  "timestamp": 1689161703599,
  "anchors": {
    "8RJ5SFxLMtk3Hhewt3u43qGHt4QEjhkAQPH35VKNhuGB": "CXShAY5JEs29BKTjcq81rxAvcBJFWN966S88pr85Zgre",
    "EBPWyefK6BXDmANjw4kDoy3ZhyDVT7ngU8Bo6ASf3x3a": "Grr6KUBEMdfGmj2yZ1YrTrXLiNA4qj8KnBwHYxnVheht"
  },
  "proofs": [
    "5rtzM1JYAQd1Pi7q2oTCaR67yTCKwqgBJ3WmKjSMtHi8TLcFmoTG4t8v4z1gdmX3QBEDssy8oFaM6DJ8D3rbrC85"
  ],
  "height": 2547600,
  "effectiveFee": 37190250
}

  • id and height should be omitted when broadcasting. These fields are set by the node.

  • Binary strings are base58 encoded.

  • timestamp is in microseconds since epoch.

  • fee includes 8 digits, so LTO * 10^8

Batch transaction

Up to 100 pairs can be anchored in a single transaction. Bundling multiple pairs in 1 transaction can help reduce transaction fees.

The Mapped Anchor fee is made up of two amounts: a fixed one plus a per-anchor one. The fees are calculated as:

0.25 + 0.1 * N

where N is the number of anchor pairs in the transaction. The total is rounded up to the nearest 100_000.

Binary schema

The binary data structure of the unsigned transaction.

#
Field Name
Type
Length

1

Transaction type

Byte (constant, value=15)

1

2

Version

Byte (constant, value=3)

1

3

Network id

Byte

1

4

Timestamp

Long

8

5

Sender's key type

KeyType (Byte)

1

6

Sender's public key

PublicKey (Array[Byte])

32 | 33

7

Fee

Long

8

8

Number of anchors

Short

2

9

Anchor 1 key length (N)

Short

2

10

Anchor 1 key

Array[Byte]

N

11

Anchor 1 value length (M)

Short

2

12

Anchor 1 value

Array[Byte]

N

...

  • Anchor key length, Anchor key, Anchor value length, and Anchor value are repeated for each anchor hash.

  • The maximum length of an anchor is 100 bytes.

  • Network id can be obtained by taking the 2nd byte from the sender address.

  • Each key type has a numeric id in addition to the reference from the JSON.

  • Integers (short, int, long) have a big endian byte order.

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