# Signing_and_Verifying_Messages

Cryptographically signed messages are a useful feature which can be used to prove ownership of an address (opens new window). If your coins (opens new window) file contains the correct message prefix (opens new window) definitions for a coin, you can sign messages with the AtomicDEX-API(https://github.com/KomodoPlatform/atomicDEX-API). This can generally be found within a coin's github repository (opens new window) and is assigned via the sign_message_prefix value as below.

{
        "coin": "RICK",
        "asset": "RICK",
        "fname": "RICK (TESTCOIN)",
        "sign_message_prefix": "Komodo Signed Message:\n",
        "rpcport": 25435,
        "txversion": 4,
        "overwintered": 1,
        "mm2": 1,
        "protocol": {
                "type": "UTXO"
        }
}

# Message Signing

# Arguments

Structure Type Description
coin string The coin to sign a message with
message string The message you want to sign

# Response

Structure Type Description
signature string The signature generated for the message

# Command

curl --url "http://127.0.0.1:7783" --data "
{
  \"userpass\": \"$userpass\",
  \"method\": \"sign_message\",
  \"mmrpc\": \"2.0\",
  \"id\": 0,
  \"params\": {
    \"coin\": \"KMD\",
    \"message\": \"Between subtle shading and the absence of light lies the nuance illusion\"
  }
}"

# Response (success)

{
  "mmrpc": "2.0",
  "result": {
    "signature": "H43eTmJxBKEPiHkrCe/8NsRidkKCIkXDxLyp30Ez/RwoApGdg89Hlvj9mTMSPGp8om5297zvdL8EVx3IdIe2swY="
  },
  "id": 0
}

# ⚠️ Error types

PrefixNotFound: sign_message_prefix is not set in coin config file CoinIsNotFound: Specified coin is not found InvalidRequest: Message signing is not supported by the given coin type InternalError: An internal error occured during the signing process

# Message Verification

# Arguments

Structure Type Description
coin string The coin to sign a message with
message string The message input via the sign_message method sign
signature string The signature generated for the message
address string The address used to sign the message

# Response

Structure Type Description
is_valid boolean true is message signature is valid; false if it is not.

# Command

curl --url "http://127.0.0.1:7783" --data "
{
  \"userpass\": \"$userpass\",
  \"method\": \"verify_message\",
  \"mmrpc\": \"2.0\",
  \"id\": 0,
  \"params\": {
    \"coin\": \"KMD\",
    \"message\": \"Between subtle shading and the absence of light lies the nuance illusion\",
    \"signature\": \"H43eTmJxBKEPiHkrCe/8NsRidkKCIkXDxLyp30Ez/RwoApGdg89Hlvj9mTMSPGp8om5297zvdL8EVx3IdIe2swY=\",
    \"address\": \"RUYJYSTuCKm9gouWzQN1LirHFEYThwzA2d\"
  }
}"

# Response (valid)

{
  "mmrpc": "2.0",
  "result": {
    "is_valid": true
  },
  "id": 0
}

# Response (not valid)

{
  "mmrpc": "2.0",
  "result": {
    "is_valid": false
  },
  "id": 0
}

# ⚠️ Error types

PrefixNotFound: sign_message_prefix is not set in coin config CoinIsNotFound: Specified coin is not found InvalidRequest: Message verification is not supported by the given coin type InternalError: An internal error occured during the verification process SignatureDecodingError: Given signature could not be decoded AddressDecodingError: Given address could not be decoded

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