Signing transactions

Every operation that contains .../assemble in its path and has a mirroring endpoint (e.g., assembling a contribution -> submitting a contribution) requires its transaction to be represented as a transactionHex string retrieved from the first request to be signed as a Hex before it is used for the second one.

For reference, see any of the following tutorials:

The exact implementation to your system may vary depending on the specific SDK or programming language being used. However, the overall sequence of events to sign a transaction should be the following:

Create a keyPair object from the public and private keys of the user's Blockchain key pair.
Retrieve the Hex string of the required transaction.
Decode the retrieved transaction Hex string.
Sign the decoded transaction.
Re-encode the signed transaction to Hex format.

The resulting encoded transaction Hex string can be used as the body for requests to the following endpoints:

http

POST /api/v1/contribution-management/contribution
PATCH /api/v1/contribution-management/contribution/flag

POST /api/v1/contribution-management/contribution
PATCH /api/v1/contribution-management/contribution/flag

Iroha SDK references

You can use any Iroha SDK available to sign a transaction. Below are references on how to sign a transaction using the following Iroha SDKs:

Iroha Java/Kotlin SDKIroha JavaScript SDKIroha Python SDK

kotlin

// Your package value:
package something

// Import dependencies:
import jp.co.soramitsu.iroha2.appendSignatures
import jp.co.soramitsu.iroha2.generated.datamodel.transaction.SignedTransaction
import jp.co.soramitsu.iroha2.keyPairFromHex
import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable
import org.bouncycastle.util.encoders.Hex
import java.io.File

// Example transaction Hex string:
// transactionHex = "0114616c69636528776f6e6465726c616e640004000d09001468656c6c6f00002cde318c87010000a0860100000000000000041c65643235353139807233bfc89dcbd68c19fde6ce6158225298ec1131b6a130d1aeb454c1ab5183c00101bef276fc36ba638abd422e76fd0e6df319df1c3d336ab60d7276333b4010bb7d962d04b273d9caf91cb8509581c0b55e1cdee371c52863a8b4b62c67fbfc870f"
fun decodeSignEncode(transactionHex: String): String {
    // Example ed25519 public key:
    val publicKey = "7fbedb314a9b0c00caef967ac5cabb982ec45da828a0c58a9aafc854f32422ac"

    // Example ed25519 private key:
    // Note: In Kotlin/Java SDK the truncated representation is more common, although you can refer to full ones represented as concatenation of private and public ones in other SDKs
    val privateKey = "413b285d1819a6166b0daa762bb6bef2d082cffb9a13ce041cb0fda5e2f06dc3"

    // Obtain 'keyPair' from the public and private keys of the 'Blockchain' key pair:
    val keyPair = keyPairFromHex(
        publicKey,
        privateKey,
        EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.ED_25519)
    )

    // Decode the transaction:
    val transaction: ByteArray = try {
        Hex.decode(transactionHex)
    } catch (e: IllegalArgumentException) {
        println("Could not decode transaction from hex format: $e")
        throw e
    }
    val decodedTransaction = transaction.let { SignedTransaction.decode(it) }

    // Sign the transaction:
    val signedTransaction = decodedTransaction.appendSignatures(keyPair)

    // Re-encode the transaction:
    val encoded = signedTransaction.let { SignedTransaction.encode(it) }
    val encodedHex = Hex.toHexString(encoded)

    // Use the value wherever needed further:
    println("Signed transaction (Hex): $encodedHex")
    return encodedHex
}

// Your package value:
package something

// Import dependencies:
import jp.co.soramitsu.iroha2.appendSignatures
import jp.co.soramitsu.iroha2.generated.datamodel.transaction.SignedTransaction
import jp.co.soramitsu.iroha2.keyPairFromHex
import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable
import org.bouncycastle.util.encoders.Hex
import java.io.File

// Example transaction Hex string:
// transactionHex = "0114616c69636528776f6e6465726c616e640004000d09001468656c6c6f00002cde318c87010000a0860100000000000000041c65643235353139807233bfc89dcbd68c19fde6ce6158225298ec1131b6a130d1aeb454c1ab5183c00101bef276fc36ba638abd422e76fd0e6df319df1c3d336ab60d7276333b4010bb7d962d04b273d9caf91cb8509581c0b55e1cdee371c52863a8b4b62c67fbfc870f"
fun decodeSignEncode(transactionHex: String): String {
    // Example ed25519 public key:
    val publicKey = "7fbedb314a9b0c00caef967ac5cabb982ec45da828a0c58a9aafc854f32422ac"

    // Example ed25519 private key:
    // Note: In Kotlin/Java SDK the truncated representation is more common, although you can refer to full ones represented as concatenation of private and public ones in other SDKs
    val privateKey = "413b285d1819a6166b0daa762bb6bef2d082cffb9a13ce041cb0fda5e2f06dc3"

    // Obtain 'keyPair' from the public and private keys of the 'Blockchain' key pair:
    val keyPair = keyPairFromHex(
        publicKey,
        privateKey,
        EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.ED_25519)
    )

    // Decode the transaction:
    val transaction: ByteArray = try {
        Hex.decode(transactionHex)
    } catch (e: IllegalArgumentException) {
        println("Could not decode transaction from hex format: $e")
        throw e
    }
    val decodedTransaction = transaction.let { SignedTransaction.decode(it) }

    // Sign the transaction:
    val signedTransaction = decodedTransaction.appendSignatures(keyPair)

    // Re-encode the transaction:
    val encoded = signedTransaction.let { SignedTransaction.encode(it) }
    val encodedHex = Hex.toHexString(encoded)

    // Use the value wherever needed further:
    println("Signed transaction (Hex): $encodedHex")
    return encodedHex
}

// @ts-check

import { crypto } from '@iroha2/crypto-target-node' // version: 1.1.1
import { datamodel } from '@iroha2/data-model' // version: 7.0.0
import { signTransaction, setCrypto, Signer } from '@iroha2/client' // version: 7.0.0
import { freeScope } from '@iroha2/crypto-core' // version: 1.1.1

setCrypto(crypto)

/**
 * @param {Uint8Array} bytes
 * @returns {string}
 */
function bytesToHex(bytes) {
  return Array.from(bytes, (v) => v.toString(16).padStart(2, '0')).join('')
}

/**
 * @param {string} hex
 * @returns {Uint8Array}
 */
function hexToBytes(hex) {
  /** @type {number[]} */
  const bytes = []
  for (let i = 0; i < hex.length; i += 2) {
    bytes.push(parseInt(hex.slice(i, i + 2), 16))
  }
  return Uint8Array.from(bytes)
}

/**
 * @param {datamodel.SignedTransactionV1} tx
 * @param {import('@iroha2/crypto-core').KeyPair} keyPair
 * @return {datamodel.SignedTransactionV1}
 */
function appendSignatureWithKeyPair(tx, keyPair) {
  const signer = new Signer(tx.payload.authority, keyPair)
  const signature = signTransaction(tx.payload, signer)
  return datamodel.SignedTransactionV1({
    payload: tx.payload,
    signatures: datamodel.SortedVecSignature([...tx.signatures, signature])
  })
}

/**
 * @param {string} publicKeyHex - ed25519 pub key hex
 * @param {string} privateKeyHex - ed25519 private key hex
 * @param {string} transaction - hex of the transaction
 * @returns {string} - hex of the transaction with the appended signature
 */
function appendSignature(publicKeyHex, privateKeyHex, transaction) {
  return freeScope(() => {
    const keyPair = crypto.KeyPair.fromJSON({
      public_key:
        // magic ed25519 multihash prefix
        'ed0120' + publicKeyHex,
      private_key: {
        digest_function: 'ed25519',
        payload: privateKeyHex
      }
    })

    const txDecoded = datamodel.SignedTransaction.fromBuffer(
      hexToBytes(transaction)
    )

    const txNew = datamodel.SignedTransaction(
      'V1',
      appendSignatureWithKeyPair(txDecoded.enum.as('V1'), keyPair)
    )

    return bytesToHex(datamodel.SignedTransaction.toBuffer(txNew))
  })
}

// example transaction
const tx = appendSignature(
  '7fbedb314a9b0c00caef967ac5cabb982ec45da828a0c58a9aafc854f32422ac',
  '413b285d1819a6166b0daa762bb6bef2d082cffb9a13ce041cb0fda5e2f06dc37fbedb314a9b0c00caef967ac5cabb982ec45da828a0c58a9aafc854f32422ac',
  '0114616c69636528776f6e6465726c616e640004000d09001468656c6c6f00002cde318c87010000a0860100000000000000041c65643235353139807233bfc89dcbd68c19fde6ce6158225298ec1131b6a130d1aeb454c1ab5183c00101bef276fc36ba638abd422e76fd0e6df319df1c3d336ab60d7276333b4010bb7d962d04b273d9caf91cb8509581c0b55e1cdee371c52863a8b4b62c67fbfc870f'
)

console.log(tx)
// => 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

// @ts-check

import { crypto } from '@iroha2/crypto-target-node' // version: 1.1.1
import { datamodel } from '@iroha2/data-model' // version: 7.0.0
import { signTransaction, setCrypto, Signer } from '@iroha2/client' // version: 7.0.0
import { freeScope } from '@iroha2/crypto-core' // version: 1.1.1

setCrypto(crypto)

/**
 * @param {Uint8Array} bytes
 * @returns {string}
 */
function bytesToHex(bytes) {
  return Array.from(bytes, (v) => v.toString(16).padStart(2, '0')).join('')
}

/**
 * @param {string} hex
 * @returns {Uint8Array}
 */
function hexToBytes(hex) {
  /** @type {number[]} */
  const bytes = []
  for (let i = 0; i < hex.length; i += 2) {
    bytes.push(parseInt(hex.slice(i, i + 2), 16))
  }
  return Uint8Array.from(bytes)
}

/**
 * @param {datamodel.SignedTransactionV1} tx
 * @param {import('@iroha2/crypto-core').KeyPair} keyPair
 * @return {datamodel.SignedTransactionV1}
 */
function appendSignatureWithKeyPair(tx, keyPair) {
  const signer = new Signer(tx.payload.authority, keyPair)
  const signature = signTransaction(tx.payload, signer)
  return datamodel.SignedTransactionV1({
    payload: tx.payload,
    signatures: datamodel.SortedVecSignature([...tx.signatures, signature])
  })
}

/**
 * @param {string} publicKeyHex - ed25519 pub key hex
 * @param {string} privateKeyHex - ed25519 private key hex
 * @param {string} transaction - hex of the transaction
 * @returns {string} - hex of the transaction with the appended signature
 */
function appendSignature(publicKeyHex, privateKeyHex, transaction) {
  return freeScope(() => {
    const keyPair = crypto.KeyPair.fromJSON({
      public_key:
        // magic ed25519 multihash prefix
        'ed0120' + publicKeyHex,
      private_key: {
        digest_function: 'ed25519',
        payload: privateKeyHex
      }
    })

    const txDecoded = datamodel.SignedTransaction.fromBuffer(
      hexToBytes(transaction)
    )

    const txNew = datamodel.SignedTransaction(
      'V1',
      appendSignatureWithKeyPair(txDecoded.enum.as('V1'), keyPair)
    )

    return bytesToHex(datamodel.SignedTransaction.toBuffer(txNew))
  })
}

// example transaction
const tx = appendSignature(
  '7fbedb314a9b0c00caef967ac5cabb982ec45da828a0c58a9aafc854f32422ac',
  '413b285d1819a6166b0daa762bb6bef2d082cffb9a13ce041cb0fda5e2f06dc37fbedb314a9b0c00caef967ac5cabb982ec45da828a0c58a9aafc854f32422ac',
  '0114616c69636528776f6e6465726c616e640004000d09001468656c6c6f00002cde318c87010000a0860100000000000000041c65643235353139807233bfc89dcbd68c19fde6ce6158225298ec1131b6a130d1aeb454c1ab5183c00101bef276fc36ba638abd422e76fd0e6df319df1c3d336ab60d7276333b4010bb7d962d04b273d9caf91cb8509581c0b55e1cdee371c52863a8b4b62c67fbfc870f'
)

console.log(tx)
// => 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

python

# Import dependency
import iroha

# Example signed transaction, encoded with SCALE codec and represented as hex string:
encoded_transaction = "010400807233bfc89dcbd68c19fde6ce6158225298ec1131b6a130d1aeb454c1ab5183c00101b65301ad504ea1430c171379ed45226bfc5fe770a216815654e20491626bbf857247bee73f6790314f892ed1a3e4c18cc6815ce9ff85ce956e0f9ab46605bc093962fb8f8e01000028776f6e6465726c616e6414616c6963650008000d09020c786f7228776f6e6465726c616e6401000000020d1402000000000000000002000000000000000d08030c786f7228776f6e6465726c616e6428776f6e6465726c616e6414616c69636501a0860100000000000000"

# Example ed25519 key pair
key_pair = iroha.KeyPair.from_json("""
{
  "public_key": "ed0120BA85186D0F8C995F8DEA6C95B3EDA321C88C983D4F6B28E079CC121B40AA8E00",
  "private_key": {
    "digest_function": "ed25519",
    "payload": "1b9068cd9b4acaabf1e8c66c622d9bd15ff3b04099819b750e3987be73d2096fba85186d0f8c995f8dea6c95b3eda321c88c983d4f6b28e079cc121b40aa8e00"
  }
}
""")

# Decode the transaction:
transaction = iroha.SignedTransaction.decode_hex(encoded_transaction)

# Sign the transaction with the provided private key:
transaction.append_signature(key_pair)

# Re-encode the transaction:
re_encoded_transaction = transaction.encode_hex()

# Retrieve the encoded Hex string of the transaction:
print(f"Signed and encoded transaction:\n{re_encoded_transaction}")

# Import dependency
import iroha

# Example signed transaction, encoded with SCALE codec and represented as hex string:
encoded_transaction = "010400807233bfc89dcbd68c19fde6ce6158225298ec1131b6a130d1aeb454c1ab5183c00101b65301ad504ea1430c171379ed45226bfc5fe770a216815654e20491626bbf857247bee73f6790314f892ed1a3e4c18cc6815ce9ff85ce956e0f9ab46605bc093962fb8f8e01000028776f6e6465726c616e6414616c6963650008000d09020c786f7228776f6e6465726c616e6401000000020d1402000000000000000002000000000000000d08030c786f7228776f6e6465726c616e6428776f6e6465726c616e6414616c69636501a0860100000000000000"

# Example ed25519 key pair
key_pair = iroha.KeyPair.from_json("""
{
  "public_key": "ed0120BA85186D0F8C995F8DEA6C95B3EDA321C88C983D4F6B28E079CC121B40AA8E00",
  "private_key": {
    "digest_function": "ed25519",
    "payload": "1b9068cd9b4acaabf1e8c66c622d9bd15ff3b04099819b750e3987be73d2096fba85186d0f8c995f8dea6c95b3eda321c88c983d4f6b28e079cc121b40aa8e00"
  }
}
""")

# Decode the transaction:
transaction = iroha.SignedTransaction.decode_hex(encoded_transaction)

# Sign the transaction with the provided private key:
transaction.append_signature(key_pair)

# Re-encode the transaction:
re_encoded_transaction = transaction.encode_hex()

# Retrieve the encoded Hex string of the transaction:
print(f"Signed and encoded transaction:\n{re_encoded_transaction}")

Submitting a contribution

Flagging a contribution

Signing transactions

Iroha SDK references

Signing transactions ​

Iroha SDK references ​

Signing transactions

Iroha SDK references