Neste guia, descrevemos como usar a API Multi-party Compute para gerenciar chaves, participantes e políticas distribuídas. Ele é destinado a clientes em pré-lançamento que estão aprendendo as principais jornadas do usuário.
Visão geral
A API MPC consiste em dois componentes principais:
- O Core MPC gerencia o ciclo de vida de chaves distribuídas, propostas e cerimônias de assinatura.
- O Policy Engine aplica a governança, autorizando as operações antes que elas sejam executadas.
Para uma análise detalhada de como o acesso à API e a assinatura criptográfica interagem, consulte Segurança e autorização.
Pré-requisitos
Antes de começar, verifique se você tem:
- Um projeto do Google Cloud . Consulte Criar projetos para saber como fazer isso.
- Se não estiver usando o Cloud Shell, a CLI
gcloudprecisa estar instalada e autenticada. As APIs necessárias precisam estar ativadas. Você precisa de duas: a nova API MPC usada neste guia e o Cloud Key Management Service, se estiver usando para gerar/assinar chaves de consentimento.
gcloud services enable mpc.googleapis.com cloudkms.googleapis.comPara conferir as APIs ativadas:
gcloud services list --enabledPython 3.9+ e as bibliotecas auxiliares do tutorial instaladas:
pip install embit eth-account eth-utils requests(Opcional) Se a organização faz a autenticação usando um provedor de identidade externo (como Okta ou Microsoft Entra ID) sem Contas do Google, consulte Configurar a federação de identidade de colaboradores (BYOID) para configurar o Application Default Credentials (ADC) com sua identidade federada.
Configuração
Atualize as variáveis a seguir para preencher os comandos neste guia.
Configuração necessária
Você precisa personalizar esses parâmetros. O guia não vai funcionar com os valores de marcador.
| Parâmetro | Valor | Descrição |
|---|---|---|
| ID do projeto | my-project |
O ID do projeto do consumidor que você forneceu para a integração na prévia. |
| ID do domínio | 67317436-0f29-ba9e-9146-d11c0bd8df9b |
O ID de domínio exclusivo que atribuímos à sua instância. |
| ID do caminho da instância | mpc-unit-bob-123 |
O ID da instância do caminho que atribuímos à sua instância. |
| Local | us-central1 |
Local de implantação. Precisa ser us-central1 (outras regiões não são compatíveis com o pré-lançamento). |
Rótulos de recursos do tutorial
Esses são os nomes dos recursos criados durante este tutorial. Os valores padrão são válidos e podem ser mantidos para minimizar o atrito de configuração.
| Parâmetro | Valor | Descrição |
|---|---|---|
| ID do keyring do Cloud KMS | mpc-assent-keys |
KeyRing do Cloud Key Management Service para chaves de assentamento externas armazenadas no Cloud KMS. |
| ID do signatário 1 | signer-alice |
Signatário 1 do MPC. |
| Signer 2 ID | signer-bob |
Signatário 2 do MPC. |
| ID do signatário 3 | signer-charlie |
Signatário 3 do MPC. |
| ID do autor da política 1 | author-dave |
Autor da política 1. |
| ID do autor da política 2 | author-eve |
Autor de políticas 2. |
| ID da política | ethereum-transfer-policy |
ID da política (por exemplo, ethereum-transfer-policy ou bitcoin-psbt-policy). |
| ID do KeyRing | my-key-ring |
ID do KeyRing. |
| ID da chave | my-key |
ID da chave. |
| ID da proposta | my-proposal |
ID da proposta. |
Etapa 1: gerar chaves de consentimento
Para usar a API MPC, é preciso gerar pares de chaves para os seguintes papéis distintos. Essas são chaves de consentimento criptográfico externas e são diferentes dos fragmentos de chave de limite de MPC distribuídos gerados internamente durante a configuração.
- Autores de políticas: autorizam políticas de governança.
- Signatários: dão consentimento (votação/aprovação) às propostas.
A. Chaves de participante (secp256k1)
Gere as chaves criptográficas necessárias para os participantes. Esses comandos são idempotentes.
Cloud KMS
Recomendamos gerenciar as chaves de consentimento no Cloud Key Management Service. Verifique se sua identidade tem permissões para criar keyrings, criar chaves, assinar e visualizar verificadores de chaves públicas (como roles/cloudkms.admin e roles/cloudkms.signerVerifier). Verifique se você tem um KeyRing criado e gere uma chave secp256k1 para todos os signatários.
provision_keyring() {
if gcloud kms keyrings describe "mpc-assent-keys" --location="us-central1" > /dev/null 2>&1; then
echo "KeyRing 'mpc-assent-keys' already exists."
else
echo "KeyRing 'mpc-assent-keys' not found. Creating it..."
gcloud kms keyrings create "mpc-assent-keys" --location="us-central1"
fi
}
provision_kms_key() {
local id=$1
if gcloud kms keys describe "${id}-key" --keyring="mpc-assent-keys" --location="us-central1" > /dev/null 2>&1; then
echo "KMS key '${id}-key' already exists."
else
echo "KMS key '${id}-key' not found. Creating it..."
gcloud kms keys create "${id}-key" \
--keyring="mpc-assent-keys" \
--location="us-central1" \
--purpose=asymmetric-signing \
--default-algorithm=ec-sign-secp256k1-sha256 \
--protection-level=hsm
fi
gcloud kms keys versions get-public-key 1 \
--key="${id}-key" \
--keyring="mpc-assent-keys" \
--location="us-central1" \
--output-file="${id}_pub.pem"
echo "Retrieved public key from KMS and saved to ${id}_pub.pem:"
cat "${id}_pub.pem"
}
# Run Setup
provision_keyring
# Generate Keys
for ID in signer-alice signer-bob signer-charlie; do
echo "Generating KMS key for $ID..."
provision_kms_key "$ID"
done
OpenSSL
Use o OpenSSL padrão para gerar chaves secp256k1 para cada participante.
provision_openssl_key() {
local id=$1
if [[ ! -f "${id}_priv.pem" ]]; then
openssl ecparam -name secp256k1 -genkey -noout -out "${id}_priv.pem"
openssl ec -in "${id}_priv.pem" -pubout -out "${id}_pub.pem"
echo "Wrote private key to ${id}_priv.pem and public key to ${id}_pub.pem:"
cat "${id}_pub.pem"
else
echo "Private key file '${id}_priv.pem' already exists. Skipping OpenSSL generation."
echo "Using existing public key from '${id}_pub.pem':"
cat "${id}_pub.pem"
fi
}
for ID in signer-alice signer-bob signer-charlie; do
echo "Generating OpenSSL key for $ID..."
provision_openssl_key "$ID"
done
B. Chaves do autor da política (secp256k1)
Cloud KMS
Da mesma forma, recomendamos gerenciar essas chaves de consentimento no Cloud Key Management Service. Verifique se sua identidade tem permissões para criar keyrings, criar chaves, assinar e visualizar verificadores de chaves públicas (como roles/cloudkms.admin e roles/cloudkms.signerVerifier). Verifique se você tem um KeyRing criado e gere uma chave secp256k1 para todos os autores de políticas.
provision_keyring() {
if gcloud kms keyrings describe "mpc-assent-keys" --location="us-central1" > /dev/null 2>&1; then
echo "KeyRing 'mpc-assent-keys' already exists."
else
echo "KeyRing 'mpc-assent-keys' not found. Creating it..."
gcloud kms keyrings create "mpc-assent-keys" --location="us-central1"
fi
}
provision_kms_key() {
local id=$1
if gcloud kms keys describe "${id}-key" --keyring="mpc-assent-keys" --location="us-central1" > /dev/null 2>&1; then
echo "KMS key '${id}-key' already exists."
else
echo "KMS key '${id}-key' not found. Creating it..."
gcloud kms keys create "${id}-key" \
--keyring="mpc-assent-keys" \
--location="us-central1" \
--purpose=asymmetric-signing \
--default-algorithm=ec-sign-secp256k1-sha256 \
--protection-level=hsm
fi
gcloud kms keys versions get-public-key 1 \
--key="${id}-key" \
--keyring="mpc-assent-keys" \
--location="us-central1" \
--output-file="${id}_pub.pem"
echo "Retrieved public key from KMS and saved to ${id}_pub.pem:"
cat "${id}_pub.pem"
}
provision_keyring
for ID in author-dave author-eve; do
echo "Generating KMS key for $ID..."
provision_kms_key "$ID"
done
OpenSSL
Os autores de políticas usam a curva secp256k1 para assinar políticas de governança e ações administrativas. É possível gerar essas chaves usando o OpenSSL padrão.
provision_openssl_key() {
local id=$1
if [[ ! -f "${id}_priv.pem" ]]; then
openssl ecparam -name secp256k1 -genkey -noout -out "${id}_priv.pem"
openssl ec -in "${id}_priv.pem" -pubout -out "${id}_pub.pem"
echo "Wrote private key to ${id}_priv.pem and public key to ${id}_pub.pem:"
cat "${id}_pub.pem"
else
echo "Private key file '${id}_priv.pem' already exists. Skipping OpenSSL generation."
echo "Using existing public key from '${id}_pub.pem':"
cat "${id}_pub.pem"
fi
}
for ID in author-dave author-eve; do
echo "Generating OpenSSL key for $ID..."
provision_openssl_key "$ID"
done
Etapa 2: registrar participantes
Antes que qualquer entidade possa participar do fluxo de MPC (como Signatário) ou do fluxo de Política (como Autor de Política), ela precisa ser registrada como Participante.
O registro requer uma coordenação fora de banda entre o Administrador e o Participante:
- A Entidade (Signatário ou Autor) gera o par de chaves localmente e transfere a Chave Pública para o Administrador de forma segura.
- O administrador (com permissões padrão do Google Cloud IAM) chama a API para registrar a chave pública.
curl
provision_participant() {
local id=$1
local name=$2
local pubkey_b64
# Read the public key from the file generated in Step 1
echo "Reading public key from ${id}_pub.pem..."
# Public key must be represented as Base64 encoded bytes of the PEM/DER format.
pubkey_b64=$(openssl base64 -A -in "${id}_pub.pem")
# Check existence
if curl -s -f -o /dev/null -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/signers/$id"; then
echo "Participant '$id' already exists. Skipping registration."
else
echo "Participant '$id' not found. Registering..."
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d "{
\"displayName\": \"$name\",
\"activePublicAssentKey\": {
\"publicKey\": \"$pubkey_b64\",
\"algorithm\": \"PUBLIC_KEY_SIGNATURE_ALGORITHM_ECDSA_SECP256K1\"
}
}" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/signers?participant_id=$id" | jq
fi
}
echo "Registering Signers..."
for ID in signer-alice signer-bob signer-charlie; do
provision_participant "$ID" "Signer $ID"
done
echo "Registering Policy Authors..."
for ID in author-dave author-eve; do
provision_participant "$ID" "Author $ID"
done
Etapa 3: configurar o Policy Engine
Configure o Policy Engine definindo o pacote de confiança e criando políticas.
A. Inicializar o pacote de confiança do autor da política
Defina quem são os autores de políticas autorizados. Este é um recurso singleton para a instância.
curl
# Get current sequence from the API. If null (initial state), fallback to 0.
NEXT_BUNDLE_SEQUENCE=$(curl -s -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policyAuthorTrustBundle" \
| jq -r '.sequenceNumber // 0')
# Calculate higher sequence number.
NEXT_BUNDLE_SEQUENCE=$((NEXT_BUNDLE_SEQUENCE + 1))
curl -X PATCH \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"sequenceNumber": '"$NEXT_BUNDLE_SEQUENCE"',
"authors": [
{"authorId": "'"author-dave"'"},
{"authorId": "'"author-eve"'"}
]
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policyAuthorTrustBundle | jq
B. Criar uma política (PENDING_ACTIVE)
Defina um ID de política (ethereum-transfer-policy ou bitcoin-psbt-policy) e crie uma regra que descreva as ações permitidas. Embora seja possível configurar muitas políticas para controlar diferentes cenários, este guia demonstra como configurar uma política para transações de Ethereum ou Bitcoin. Por padrão, o Policy Engine é Fail-Fast (bloqueio por padrão). Se nenhuma política permitir explicitamente uma transação, ela será negada.
Antes de criar ou aprovar uma política, os autores precisam assinar um payload que represente a intent. Use as seguintes funções auxiliares para processar a serialização e a assinatura binárias.
Ethereum
Essa regra permite transferências menores de Ethereum (<= 2 ETH, representados como 2.000.000.000 Gwei) para um endereço específico de Alice.
1. Gerar assinatura de quórum
Como usar o Cloud KMS:
sign_policy() {
local author_id=$1
local sequence=$2
local cedar_doc=$3
local policy_id=$4
export _HELPER_POLICY_ID="$policy_id"
export _HELPER_SEQUENCE="$sequence"
export _HELPER_CEDAR_DOC="$cedar_doc"
python3 -c "import os; p='my-project'; l='us-central1'; i='mpc-unit-bob-123'; pol=os.environ.get('_HELPER_POLICY_ID'); s=int(os.environ.get('_HELPER_SEQUENCE')); d=os.environ.get('_HELPER_CEDAR_DOC'); n=f'projects/{p}/locations/{l}/instances/{i}/policyEngine/policies/{pol}'; payload=b'action:ACTIVE\n'+n.encode('utf-8')+b'sequence:'+s.to_bytes(8,'little')+b'cedar_document:'+d.encode('utf-8'); open('payload.bin', 'wb').write(payload)"
gcloud kms asymmetric-sign \
--version=1 \
--key="${author_id}-key" \
--keyring="mpc-assent-keys" \
--location="us-central1" \
--digest-algorithm=sha256 \
--input-file=payload.bin \
--signature-file=policy_sig.bin > /dev/null
openssl base64 -A -in policy_sig.bin
}
# Sign as Author 1 (Sequence 0)
QUORUM_SIGNATURE=$(sign_policy "author-dave" 0 'permit(principal == User::"alice", action == Action::"Transfer", resource == Resource::"mpc_operation") when { context.transaction.to_address == "0x1111111111111111111111111111111111111111" && context.transaction.value_gwei <= 2000000000 };' "ethereum-transfer-policy")
Como usar o OpenSSL:
sign_policy() {
local author_id=$1
local sequence=$2
local cedar_doc=$3
local policy_id=$4
export _HELPER_POLICY_ID="$policy_id"
export _HELPER_SEQUENCE="$sequence"
export _HELPER_CEDAR_DOC="$cedar_doc"
python3 -c "import os; p='my-project'; l='us-central1'; i='mpc-unit-bob-123'; pol=os.environ.get('_HELPER_POLICY_ID'); s=int(os.environ.get('_HELPER_SEQUENCE')); d=os.environ.get('_HELPER_CEDAR_DOC'); n=f'projects/{p}/locations/{l}/instances/{i}/policyEngine/policies/{pol}'; payload=b'action:ACTIVE\n'+n.encode('utf-8')+b'sequence:'+s.to_bytes(8,'little')+b'cedar_document:'+d.encode('utf-8'); open('payload.bin', 'wb').write(payload)"
openssl dgst -sha256 -sign "${author_id}_priv.pem" -out policy_sig.bin payload.bin
openssl base64 -A -in policy_sig.bin
}
# Sign as Author 1 (Sequence 0)
QUORUM_SIGNATURE=$(sign_policy "author-dave" 0 'permit(principal == User::"alice", action == Action::"Transfer", resource == Resource::"mpc_operation") when { context.transaction.to_address == "0x1111111111111111111111111111111111111111" && context.transaction.value_gwei <= 2000000000 };' "ethereum-transfer-policy")
2. Chamar a API CreatePolicy
# Check existence
if curl -s -f -o /dev/null -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/ethereum-transfer-policy"; then
echo "Policy 'ethereum-transfer-policy' already exists. Skipping creation."
else
echo "Policy 'ethereum-transfer-policy' not found. Creating..."
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"displayName": "Ethereum Transfer Permit Policy",
"rule": {
"cedarDocument": "permit(principal == User::\"alice\", action == Action::\"Transfer\", resource == Resource::\"mpc_operation\") when { context.transaction.to_address == \"0x1111111111111111111111111111111111111111\" && context.transaction.value_gwei <= 2000000000 };"
},
"createAuthorSignature": {
"authorId": "'"author-dave"'",
"signature": "'"$QUORUM_SIGNATURE"'",
"approvalTime": "'"$(date -u +"%Y-%m-%dT%H:%M:%SZ")"'"
}
}' \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies?policy_id=ethereum-transfer-policy" | jq
fi
Bitcoin
Essa regra permite transferências de Bitcoin usando o esquema bitcoin.transaction.v2 (BIP 174 PSBT), em que o valor líquido da transferência de saída não excede 250.000 satoshis (context.transaction.spend_amount_scaled <= 2500000 ou 0,0025 BTC normalizado para 10-9 unidades decimais fixas) e a taxa do minerador não excede 10.000 satoshis (context.transaction.max_fee_atomic <= 100000).
permit(
principal == User::"alice",
action == Action::"Transfer",
resource == Resource::"mpc_operation"
)
when {
context.transaction.schema == "bitcoin.transaction.v2" &&
context.transaction.spend_amount_scaled <= 2500000 &&
context.transaction.max_fee_atomic <= 100000
};
1. Gerar assinatura de quórum
Como usar o Cloud KMS:
sign_policy() {
local author_id=$1
local sequence=$2
local cedar_doc=$3
local policy_id=$4
export _HELPER_POLICY_ID="$policy_id"
export _HELPER_SEQUENCE="$sequence"
export _HELPER_CEDAR_DOC="$cedar_doc"
python3 -c "import os; p='my-project'; l='us-central1'; i='mpc-unit-bob-123'; pol=os.environ.get('_HELPER_POLICY_ID'); s=int(os.environ.get('_HELPER_SEQUENCE')); d=os.environ.get('_HELPER_CEDAR_DOC'); n=f'projects/{p}/locations/{l}/instances/{i}/policyEngine/policies/{pol}'; payload=b'action:ACTIVE\n'+n.encode('utf-8')+b'sequence:'+s.to_bytes(8,'little')+b'cedar_document:'+d.encode('utf-8'); open('payload.bin', 'wb').write(payload)"
gcloud kms asymmetric-sign \
--version=1 \
--key="${author_id}-key" \
--keyring="mpc-assent-keys" \
--location="us-central1" \
--digest-algorithm=sha256 \
--input-file=payload.bin \
--signature-file=policy_sig.bin > /dev/null
openssl base64 -A -in policy_sig.bin
}
# Sign as Author 1 (Sequence 0)
QUORUM_SIGNATURE=$(sign_policy "author-dave" 0 'permit(principal == User::"alice", action == Action::"Transfer", resource == Resource::"mpc_operation") when { context.transaction.schema == "bitcoin.transaction.v2" && context.transaction.spend_amount_scaled <= 2500000 && context.transaction.max_fee_atomic <= 100000 };' "bitcoin-psbt-policy")
Como usar o OpenSSL:
sign_policy() {
local author_id=$1
local sequence=$2
local cedar_doc=$3
local policy_id=$4
export _HELPER_POLICY_ID="$policy_id"
export _HELPER_SEQUENCE="$sequence"
export _HELPER_CEDAR_DOC="$cedar_doc"
python3 -c "import os; p='my-project'; l='us-central1'; i='mpc-unit-bob-123'; pol=os.environ.get('_HELPER_POLICY_ID'); s=int(os.environ.get('_HELPER_SEQUENCE')); d=os.environ.get('_HELPER_CEDAR_DOC'); n=f'projects/{p}/locations/{l}/instances/{i}/policyEngine/policies/{pol}'; payload=b'action:ACTIVE\n'+n.encode('utf-8')+b'sequence:'+s.to_bytes(8,'little')+b'cedar_document:'+d.encode('utf-8'); open('payload.bin', 'wb').write(payload)"
openssl dgst -sha256 -sign "${author_id}_priv.pem" -out policy_sig.bin payload.bin
openssl base64 -A -in policy_sig.bin
}
# Sign as Author 1 (Sequence 0)
QUORUM_SIGNATURE=$(sign_policy "author-dave" 0 'permit(principal == User::"alice", action == Action::"Transfer", resource == Resource::"mpc_operation") when { context.transaction.schema == "bitcoin.transaction.v2" && context.transaction.spend_amount_scaled <= 2500000 && context.transaction.max_fee_atomic <= 100000 };' "bitcoin-psbt-policy")
2. Chamar a API CreatePolicy
# Check existence
if curl -s -f -o /dev/null -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/bitcoin-psbt-policy"; then
echo "Policy 'bitcoin-psbt-policy' already exists. Skipping creation."
else
echo "Policy 'bitcoin-psbt-policy' not found. Creating..."
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"displayName": "Bitcoin PSBT Permit Policy",
"rule": {
"cedarDocument": "permit(principal == User::\"alice\", action == Action::\"Transfer\", resource == Resource::\"mpc_operation\") when { context.transaction.schema == \"bitcoin.transaction.v2\" && context.transaction.spend_amount_scaled <= 2500000 && context.transaction.max_fee_atomic <= 100000 };"
},
"createAuthorSignature": {
"authorId": "'"author-dave"'",
"signature": "'"$QUORUM_SIGNATURE"'",
"approvalTime": "'"$(date -u +"%Y-%m-%dT%H:%M:%SZ")"'"
}
}' \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies?policy_id=bitcoin-psbt-policy" | jq
fi
C. Política de aprovação (transição para ACTIVE)
Se a configuração da política exigir assinaturas M-of-N, os autores subsequentes vão chamar AddQuorumSignature.
Para gerar a assinatura, primeiro é preciso recuperar a sequência atual da política.
Ethereum
# 1. Get the policy state and sequence
POLICY_INFO=$(curl -s -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/ethereum-transfer-policy")
POLICY_STATE=$(echo "$POLICY_INFO" | jq -r '.state // "UNKNOWN"')
if [ "$POLICY_STATE" == "PENDING_ACTIVE" ]; then
POLICY_SEQUENCE=$(echo "$POLICY_INFO" | jq -r '.globalSequence // 0')
echo "Policy Sequence: $POLICY_SEQUENCE"
# 2. Sign as Author 2
QUORUM_SIGNATURE_SEQ=$(sign_policy "author-eve" $POLICY_SEQUENCE 'permit(principal == User::"alice", action == Action::"Transfer", resource == Resource::"mpc_operation") when { context.transaction.to_address == "0x1111111111111111111111111111111111111111" && context.transaction.value_gwei <= 2000000000 };' "ethereum-transfer-policy")
# 3. Call AddQuorumSignature
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"name": "projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/ethereum-transfer-policy",
"signature": {
"authorId": "'"author-eve"'",
"signature": "'"$QUORUM_SIGNATURE_SEQ"'",
"approvalTime": "'"$(date -u +"%Y-%m-%dT%H:%M:%SZ")"'"
}
}' \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/ethereum-transfer-policy:addQuorumSignature" | jq
elif [ "$POLICY_STATE" == "ACTIVE" ]; then
echo "Policy 'ethereum-transfer-policy' is already ACTIVE. Skipping signature."
else
echo "Policy 'ethereum-transfer-policy' is in an unknown or unexpected state: $POLICY_STATE"
fi
Bitcoin
# 1. Get the policy state and sequence
POLICY_INFO=$(curl -s -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/bitcoin-psbt-policy")
POLICY_STATE=$(echo "$POLICY_INFO" | jq -r '.state // "UNKNOWN"')
if [ "$POLICY_STATE" == "PENDING_ACTIVE" ]; then
POLICY_SEQUENCE=$(echo "$POLICY_INFO" | jq -r '.globalSequence // 0')
echo "Policy Sequence: $POLICY_SEQUENCE"
# 2. Sign as Author 2
QUORUM_SIGNATURE_SEQ=$(sign_policy "author-eve" $POLICY_SEQUENCE 'permit(principal == User::"alice", action == Action::"Transfer", resource == Resource::"mpc_operation") when { context.transaction.schema == "bitcoin.transaction.v2" && context.transaction.spend_amount_scaled <= 2500000 && context.transaction.max_fee_atomic <= 100000 };' "bitcoin-psbt-policy")
# 3. Call AddQuorumSignature
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"name": "projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/bitcoin-psbt-policy",
"signature": {
"authorId": "'"author-eve"'",
"signature": "'"$QUORUM_SIGNATURE_SEQ"'",
"approvalTime": "'"$(date -u +"%Y-%m-%dT%H:%M:%SZ")"'"
}
}' \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/bitcoin-psbt-policy:addQuorumSignature" | jq
elif [ "$POLICY_STATE" == "ACTIVE" ]; then
echo "Policy 'bitcoin-psbt-policy' is already ACTIVE. Skipping signature."
else
echo "Policy 'bitcoin-psbt-policy' is in an unknown or unexpected state: $POLICY_STATE"
fi
Etapa 4: criar uma chave
Agora, criamos um keyring e geramos uma chave distribuída.
A. Criar KeyRing
Agrupamento lógico para suas chaves de MPC.
curl
# Check existence
if curl -s -f -o /dev/null -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring"; then
echo "KeyRing 'my-key-ring' already exists. Skipping creation."
else
echo "KeyRing 'my-key-ring' not found. Creating..."
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings?key_ring_id=my-key-ring | jq
fi
B. Gerar chave distribuída (DKG)
Inicie uma cerimônia assíncrona para gerar uma chave distribuída entre os participantes.
curl
# Check existence
if curl -s -f -o /dev/null -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key"; then
echo "Key 'my-key' already exists. Skipping generation."
else
echo "Key 'my-key' not found. Generating..."
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"threshold": 2,
"algorithm": "ECDSA_SECP256K1",
"participantShares": [
{"participantId": "projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/signers/signer-alice"},
{"participantId": "projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/signers/signer-bob"},
{"participantId": "projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/signers/signer-charlie"}
]
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys?key_id=my-key | jq
fi
Isso retorna uma operação de longa duração (LRO, na sigla em inglês). Aguarde até que a chave state se torne ACTIVE (o que significa que a cerimônia de DKG foi concluída).
🕵️♂️ Verificar o estado da chave (pesquisa)
Consulte o status da chave executando o comando a seguir periodicamente até que o campo state na resposta se torne ACTIVE (indicando que a cerimônia de DKG foi concluída).
curl
curl -X GET \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key | jq
C. Derivar endereço de blockchain e localizar UTXOs
Depois que a chave distribuída se torna ACTIVE, a chave MPC está pronta para uso. Nesta etapa, você deriva o endereço específico do blockchain da chave pública não compactada de 65 bytes retornada pela geração de chaves MPC (0x04 || X || Y) e localiza os fundos não gastos necessários para as transações.
Ethereum
Os endereços do Ethereum são derivados do hash Keccak-256 do ponto de chave pública não compactado de 64 bytes (pub_bytes[1:]), considerando os últimos 20 bytes.
Script de derivação de endereço (derive_address.py)
Execute o bloco a seguir para criar e executar derive_address.py:
cat <<'EOF' > derive_address.py
import base64
from eth_utils import keccak, to_checksum_address
# Insert your base64 public_key from Step 4.B
PUBLIC_KEY_B64 = "your-public-key"
pub_bytes = base64.b64decode(PUBLIC_KEY_B64)
if len(pub_bytes) == 65 and pub_bytes[0] == 4:
raw_addr = "0x" + keccak(pub_bytes[1:])[-20:].hex()
checksummed_addr = to_checksum_address(raw_addr)
print("Ethereum Address:", checksummed_addr)
else:
print(f"Error: Expected 65-byte uncompressed key, got {len(pub_bytes)} bytes.")
EOF
python3 derive_address.py
Financiar o endereço do Ethereum
Antes de transmitir na Etapa 6, verifique se o endereço Ethereum derivado tem ETH suficiente na rede de teste Sepolia para cobrir o valor da transação e os custos de gas. Para solicitar ETH de testnet sem custo financeiro, insira o endereço recém-derivado no Faucet para Ethereum Sepolia.
Bitcoin
Os endereços de Bitcoin são derivados da chave pública EC secp256k1 de 65 bytes descompactada (0x04 || X || Y). Vários formatos de endereço são compatíveis com a mesma chave pública:
- Native SegWit (P2WPKH / BIP 173): endereço Bech32 (
bc1q...na Mainnet,tb1q...na Testnet4) com um witnessscriptPubKeyde 22 bytes (0014<hash160>). Esse é o formato moderno recomendado com as menores taxas de transação. - SegWit aninhado (P2SH-P2WPKH / BIP 49): endereço SegWit encapsulado (
3...na Mainnet,2...na Testnet4) com umscriptPubKey(a914<hash160>87) de 23 bytes e um redeemScript (0014<hash160>) de 22 bytes, compatível com sistemas legados. - Legado (P2PKH / BIP 44): endereço Base58 original de Pay-to-PubKey-Hash (
1...na Mainnet,m/n...na Testnet4) com umscriptPubKey(76a914<hash160>88ac) de 25 bytes.
Script de derivação de endereço (derive_btc_address.py)
Execute o bloco a seguir para criar e executar derive_btc_address.py:
cat <<'EOF' > derive_btc_address.py
"""Derives Bitcoin addresses (Native SegWit, Nested SegWit, Legacy) from an MPC public key using embit."""
import base64
from embit import ec, script
from embit.networks import NETWORKS
# Insert the Base64-encoded public key from Step 4.B (publicKey field, decodes to 65 raw bytes)
PUBLIC_KEY_B64 = "your-public-key"
raw_bytes = base64.b64decode(PUBLIC_KEY_B64)
if len(raw_bytes) != 65 or raw_bytes[0] != 4:
raise ValueError(f"Expected 65-byte uncompressed public key (0x04...), got {len(raw_bytes)} bytes")
# 1. Parse and compress public key to 33 bytes
pub = ec.PublicKey.parse(raw_bytes)
pub.compressed = True
compressed_pubkey_hex = pub.sec().hex()
print("================================================================")
print(f"Compressed Public Key (33 bytes): {compressed_pubkey_hex}")
print("================================================================")
# 2. Native SegWit (P2WPKH - BIP 173)
p2wpkh = script.p2wpkh(pub)
print("\n[1. Native SegWit (P2WPKH / Bech32 - BIP 173)]")
print(f" ScriptPubKey: {p2wpkh.data.hex()}")
print(f" Testnet4 Address (tb): {p2wpkh.address(NETWORKS['test'])}")
print(f" Mainnet Address (bc): {p2wpkh.address(NETWORKS['main'])}")
# 3. Nested SegWit (P2SH-P2WPKH - BIP 49)
p2sh_p2wpkh = script.p2sh(p2wpkh)
print("\n[2. Nested SegWit (P2SH-P2WPKH / Base58 - BIP 49)]")
print(f" RedeemScript: {p2wpkh.data.hex()}")
print(f" ScriptPubKey: {p2sh_p2wpkh.data.hex()}")
print(f" Testnet4 Address (2): {p2sh_p2wpkh.address(NETWORKS['test'])}")
print(f" Mainnet Address (3): {p2sh_p2wpkh.address(NETWORKS['main'])}")
# 4. Legacy (P2PKH - BIP 44)
p2pkh = script.p2pkh(pub)
print("\n[3. Legacy (P2PKH / Base58 - BIP 44)]")
print(f" ScriptPubKey: {p2pkh.data.hex()}")
print(f" Testnet4 Address (m/n): {p2pkh.address(NETWORKS['test'])}")
print(f" Mainnet Address (1): {p2pkh.address(NETWORKS['main'])}")
EOF
python3 derive_btc_address.py
Como localizar saídas não gastas (UTXOs)
Ao contrário dos blockchains baseados em contas, as transações de Bitcoin gastam saídas de transação não gastas (UTXOs, na sigla em inglês) específicas. Antes de criar uma transação na Etapa 5:
- Adicione fundos ao seu endereço Native SegWit derivado (por exemplo, usando um faucet de testnet).
- Consulte os UTXOs não gastos do seu endereço usando o nó do Bitcoin (
bitcoin-cli listunspent 1 9999999 "[\"tb1q...\"]") ou uma API de explorador de blocos. - Observe os quatro parâmetros a seguir para a Etapa 5:
txid: o hash de transação de 32 bytes da saída não gasta.vout: o índice de saída com indexação zero (por exemplo,0ou1).value: o valor não gasto em satoshis (por exemplo,200000satoshis = 0,002 BTC).scriptPubKey: o hexadecimal do script de bloqueio (por exemplo,0014...).
Etapa 5: executar uma operação de MPC
Executar uma operação de MPC avaliando uma transação e criando uma proposta.
A. Avaliar transação (receber token de autorização)
Antes de assinar uma operação de MPC, autorize o payload de acordo com suas políticas para receber um token JWS e o resumo de assinatura de 32 bytes.
Ethereum
🛑 Caso A: rejeição (valor muito alto)
Tente autorizar uma transação de 3 ETH (excede nosso limite de 2 ETH).
# Payload for 3 ETH (Hex equivalent contains value_gwei > 2B)
RAW_TX_BYTES_HEX="ef808504a817c8008252089411111111111111111111111111111111111111118829a2241af62c00008083aa36a78080"
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"principal": "User::\"alice\"",
"action": "Action::\"Transfer\"",
"resource": "Resource::\"mpc_operation\"",
"schema": "ETHEREUM_TX_V1",
"payload": "'"$RAW_TX_BYTES_HEX"'"
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine:authorizePayload | jq
Resposta esperada: decision: DENY
✅ Caso B: aprovação (valor permitido)
Tente autorizar uma transação de 1 Gwei (dentro do nosso limite de 2 ETH).
# Payload for 1 Gwei
RAW_TX_BYTES_HEX="eb808504a817c800825208941111111111111111111111111111111111111111843b9aca008083aa36a78080"
RESPONSE=$(curl -s -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"principal": "User::\"alice\"",
"action": "Action::\"Transfer\"",
"resource": "Resource::\"mpc_operation\"",
"schema": "ETHEREUM_TX_V1",
"payload": "'"$RAW_TX_BYTES_HEX"'"
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine:authorizePayload)
echo "$RESPONSE" | jq
# Automatically capture variables for next steps
DIGEST_HEX=$(echo "$RESPONSE" | jq -r .digest)
POLICY_ENGINE_TOKEN=$(echo "$RESPONSE" | jq -r .token)
# Convert to Base64 (which curl expects for bytes fields)
DIGEST_B64=$(python3 -c "import base64; print(base64.b64encode(bytes.fromhex('$DIGEST_HEX')).decode('utf-8'))")
POLICY_ENGINE_TOKEN_B64=$(python3 -c "import base64; print(base64.b64encode('$POLICY_ENGINE_TOKEN'.encode('utf-8')).decode('utf-8'))")
Resposta esperada: decision: PERMIT com um token.
Bitcoin
No modelo UTXO do Bitcoin, as transações gastam saídas específicas não gastas. No SegWit (BIP 143), para calcular o hash de assinatura, é preciso saber o valor em satoshis e o script de bloqueio da entrada que está sendo gasta.
O Policy Engine requer o formato BIP 174 PSBT v0 (BITCOIN_TX_V2) com PSBT_IN_WITNESS_UTXO preenchido para cada entrada.
Script de construção de PSBT (build_psbt.py)
Execute o bloco a seguir para montar um payload válido do BIP 174 PSBT v0:
cat <<'EOF' > build_psbt.py
"""Constructs a BIP 174 PSBT v0 payload using embit for Bitcoin policy evaluation."""
from embit import script, transaction
from embit.psbt import PSBT
# 1. Inputs (From Step 4.C)
PREV_TXID_HEX = "8f594f33156993f1c980c2273dcae4a92cf2517fbc29264421395e63a63916d8"
PREV_VOUT = int("1")
INPUT_VALUE_SATS = int("200000") # Total UTXO input value in satoshis
SENDER_SCRIPTPUBKEY_HEX = "0014eced05cd51d964102a20c856b09080ad620e9da2"
# 2. Output Allocations
RECIPIENT_SATS = int("50000") # Recipient payment in satoshis
MINER_FEE_SATS = int("250") # Miner fee in satoshis
RECIPIENT_SCRIPTPUBKEY_HEX = "0014751e76e8199196d454941c45d1b3a323f1433bd6"
# Change Output calculation: InputSats - RecipientSats - MinerFeeSats
CHANGE_SATS = INPUT_VALUE_SATS - RECIPIENT_SATS - MINER_FEE_SATS
if CHANGE_SATS <= 0:
raise ValueError(f"Insufficient input satoshis ({INPUT_VALUE_SATS}) for payment and fee")
# 3. Construct Unsigned Transaction (Version 2, 1 input, 2 outputs, locktime 0)
tx = transaction.Transaction(
version=2,
vin=[transaction.TransactionInput(
txid=bytes.fromhex(PREV_TXID_HEX),
vout=PREV_VOUT,
sequence=0xFFFFFFFF,
)],
vout=[
transaction.TransactionOutput(
value=RECIPIENT_SATS,
script_pubkey=script.Script(bytes.fromhex(RECIPIENT_SCRIPTPUBKEY_HEX)),
),
transaction.TransactionOutput(
value=CHANGE_SATS,
script_pubkey=script.Script(bytes.fromhex(SENDER_SCRIPTPUBKEY_HEX)),
),
],
locktime=0,
)
# 4. Package into BIP 174 PSBT with Input Witness UTXO
psbt = PSBT(tx)
psbt.inputs[0].witness_utxo = transaction.TransactionOutput(
value=INPUT_VALUE_SATS,
script_pubkey=script.Script(bytes.fromhex(SENDER_SCRIPTPUBKEY_HEX)),
)
print(psbt.serialize().hex())
EOF
BTC_PSBT_HEX=$(python3 build_psbt.py)
echo "Generated PSBT Hex (${#BTC_PSBT_HEX} chars):"
echo "$BTC_PSBT_HEX"
🛑 Caso A: rejeição (limite de taxa excedido)
Tentativa de autorizar uma transação em que a taxa de mineração excede o limite de 10.000 satoshis da política. Neste exemplo, definir MINER_FEE_SATS = 15000 (e CHANGE_SATS = 135000) em build_psbt.py é escalonado para max_fee_atomic = 150000 (excedendo o limite da política de 100000), produzindo o seguinte payload que aciona uma decisão DENY do Policy Engine.
# Construct a PSBT payload with miner_fee_sats = 15000 -> max_fee_atomic = 150000 (exceeds 100000 limit)
REJECTED_PSBT_HEX="70736274ff0100710200000001d81639a6635e3921442629bc7f51f22ca9e4ca3d27c280c9f1936915334f598f0100000000ffffffff0250c3000000000000160014751e76e8199196d454941c45d1b3a323f1433bd6580f020000000000160014eced05cd51d964102a20c856b09080ad620e9da2000000000001011f400d030000000000160014eced05cd51d964102a20c856b09080ad620e9da2000000"
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"principal": "User::\"alice\"",
"action": "Action::\"Transfer\"",
"resource": "Resource::\"mpc_operation\"",
"schema": "BITCOIN_TX_V2",
"payload": "'"$REJECTED_PSBT_HEX"'"
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine:authorizePayload | jq
Resposta esperada: decision: DENY
✅ Caso B: aprovação (PSBT de Bitcoin permitida)
Tente autorizar o PSBT válido criado anteriormente (RECIPIENT_SATS = 50000 é mapeado para spend_amount_scaled = 500000 <= 2500000 e MINER_FEE_SATS = 250 é mapeado para max_fee_atomic = 2500 <= 100000).
RESPONSE=$(curl -s -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"principal": "User::\"alice\"",
"action": "Action::\"Transfer\"",
"resource": "Resource::\"mpc_operation\"",
"schema": "BITCOIN_TX_V2",
"payload": "'"$BTC_PSBT_HEX"'"
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine:authorizePayload)
echo "$RESPONSE" | jq
# Automatically capture variables for next steps
DIGEST_HEX=$(echo "$RESPONSE" | jq -r .digest)
POLICY_ENGINE_TOKEN=$(echo "$RESPONSE" | jq -r .token)
# Convert to Base64 (which curl expects for bytes fields)
DIGEST_B64=$(python3 -c "import base64; print(base64.b64encode(bytes.fromhex('$DIGEST_HEX')).decode('utf-8'))")
POLICY_ENGINE_TOKEN_B64=$(python3 -c "import base64; print(base64.b64encode('$POLICY_ENGINE_TOKEN'.encode('utf-8')).decode('utf-8'))")
Resposta esperada: decision: PERMIT com um JWS token e um sighash BIP 143 de 32 bytes digest.
Isso retorna:
decision:PERMITouDENY.token: o token da política JWS (comprovante de conformidade).digest: o resumo de assinatura de 32 bytes com codificação hexadecimal.evaluatedPolicyIds: políticas que foram avaliadas e afetaram a decisão.
B. Criar proposta (iniciar assinatura)
Ofereça o payload de resumo para assinatura, anexando o token do Policy Engine recebido na Etapa 5A.
curl
# Check existence
if curl -s -f -o /dev/null -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals/my-proposal"; then
echo "Proposal 'my-proposal' already exists. Skipping creation."
else
echo "Proposal 'my-proposal' not found. Creating..."
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"digest": "'"$DIGEST_B64"'",
"keyVersion": "projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/versions/1",
"initiator": "projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/signers/signer-alice",
"policyApproverSignature": "'"$POLICY_ENGINE_TOKEN_B64"'"
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals?proposal_id=my-proposal | jq
fi
Isso retorna uma operação de longa duração (LRO, na sigla em inglês). A proposta state esperada será PENDING_ASSENT (indicando que está pronta para ser assinada pelos participantes).
🕵️♂️ Verificar o estado da proposta (pesquisa)
Para consultar o status da proposta, execute o comando a seguir periodicamente.
curl
curl -X GET \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals/my-proposal | jq
C. Registrar decisões dos participantes (consentimento)
Os participantes precisam assinar o hash da proposta com as chaves privadas locais (compartilhamentos de chaves) e encaminhar o consentimento.
1. Resumo da proposta de assinatura
Cloud KMS
sign_digest() {
local signer_id=$1
local digest_hex=$2
local digest_b64=$(python3 -c "import base64, sys; print(base64.b64encode(bytes.fromhex('$digest_hex')).decode('utf-8'))")
# Direct API calls are used here because the input is already a pre-computed 32-byte digest from the MPC.
# Tools like gcloud assume input is raw data and apply a redundant hashing layer, altering the payload.
# Unlike Policy signings which hash raw administrative text, Proposal signatures must sign this exact 32-byte hash as-is.
curl -s -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "Content-Type: application/json" \
-d "{\"digest\": {\"sha256\": \"$digest_b64\"}}" \
https://cloudkms.googleapis.com/v1/projects/my-project/locations/us-central1/keyRings/mpc-assent-keys/cryptoKeys/${signer_id}-key/cryptoKeyVersions/1:asymmetricSign | jq -r .signature
}
SIGNER_2_SIG_B64=$(sign_digest "signer-bob" "$DIGEST_HEX")
SIGNER_3_SIG_B64=$(sign_digest "signer-charlie" "$DIGEST_HEX")
OpenSSL
sign_digest() {
local signer_id=$1
local digest_hex=$2
python3 -c "import sys; sys.stdout.buffer.write(bytes.fromhex('$digest_hex'))" > digest.bin
openssl pkeyutl -sign -inkey "${signer_id}_priv.pem" -in digest.bin -out digest_sig.bin
openssl base64 -A -in digest_sig.bin
}
SIGNER_2_SIG_B64=$(sign_digest "signer-bob" "$DIGEST_HEX")
SIGNER_3_SIG_B64=$(sign_digest "signer-charlie" "$DIGEST_HEX")
2. Registrar decisão
curl
# 1. Check state for Signer 2
PROPOSAL_INFO=$(curl -s -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals/my-proposal")
PROPOSAL_STATE=$(echo "$PROPOSAL_INFO" | jq -r '.state // "UNKNOWN"')
if [ "$PROPOSAL_STATE" == "PENDING_ASSENT" ]; then
echo "Recording assent for Signer 2..."
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"signature": "'"$SIGNER_2_SIG_B64"'",
"decision": "ASSENT",
"participant": "signer-bob"
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals/my-proposal:recordParticipantDecision | jq
elif [ "$PROPOSAL_STATE" == "READY" ] || [ "$PROPOSAL_STATE" == "SUCCEEDED" ]; then
echo "Proposal is in state $PROPOSAL_STATE. Skipping Signer 2."
else
echo "Proposal is in an unknown or unexpected state: $PROPOSAL_STATE"
fi
# 2. Re-check state for Signer 3 (Signer 2 might have triggered a state change)
PROPOSAL_INFO=$(curl -s -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
"https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals/my-proposal")
PROPOSAL_STATE=$(echo "$PROPOSAL_INFO" | jq -r '.state // "UNKNOWN"')
if [ "$PROPOSAL_STATE" == "PENDING_ASSENT" ]; then
echo "Recording assent for Signer 3..."
curl -X POST \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
-H "Content-Type: application/json" \
-d '{
"signature": "'"$SIGNER_3_SIG_B64"'",
"decision": "ASSENT",
"participant": "signer-charlie"
}' \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals/my-proposal:recordParticipantDecision | jq
elif [ "$PROPOSAL_STATE" == "READY" ] || [ "$PROPOSAL_STATE" == "SUCCEEDED" ]; then
echo "Proposal is in state $PROPOSAL_STATE. Skipping Signer 3."
else
echo "Proposal is in an unknown or unexpected state: $PROPOSAL_STATE"
fi
D. Buscar assinatura final
Quando o limite de aprovações for atingido, verifique o estado da proposta ou busque a assinatura.
curl
curl -X GET \
-H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals/my-proposal | jq
Se a proposta estiver no estado SUCCEEDED, consulte o campo finalSignature no JSON retornado.
Etapa 6: transmitir a transação para o blockchain
Depois que a proposta atingir o estado SUCCEEDED e você tiver buscado o finalSignature, a última etapa será criar a transação eletrônica assinada e transmiti-la para a rede.
Ethereum
Derivação e transmissão do identificador de recuperação
A API MPC retorna uma assinatura ECDSA bruta de 64 bytes (composta pelos valores r e s). O servidor garante que a assinatura esteja no formato canônico low-s (EIP-2). No entanto, o Ethereum exige um identificador de recuperação (v) para derivar o endereço do remetente e verificar a assinatura, que não é retornada diretamente em assinaturas MPC padrão de 64 bytes.
O script Python a seguir lida com essa complexidade. Ele determina dinamicamente o bit de recuperação correto ao corresponder ao endereço do remetente esperado, cria a transação válida e a transmite para a rede.
Script de transmissão:
Execute o seguinte bloco de copiar e colar no terminal para gravar e executar broadcast_eth.py:
cat <<'EOF' > broadcast_eth.py
"""Broadcasts an Ethereum transaction using a normalized MPC signature."""
import base64
import os
import requests
from eth_account import Account
try:
from eth_account._utils.transactions import encode_transaction, serializable_unsigned_transaction_from_dict
except ImportError:
from eth_account._utils.legacy_transactions import encode_transaction, serializable_unsigned_transaction_from_dict
# ==========================================
# 1. INPUTS
# ==========================================
FINAL_SIGNATURE_B64 = "your-final-signature"
RPC_URL = "https://ethereum-sepolia-rpc.publicnode.com"
EXPECTED_SENDER = "0xyour-mpc-key-address"
if not FINAL_SIGNATURE_B64 or FINAL_SIGNATURE_B64 == "your-final-signature":
raise ValueError("FINAL_SIGNATURE_B64 is not set. Please provide a valid signature.")
# ==========================================
# 2. TRANSACTION PARAMETERS
# ==========================================
CHAIN_ID = 11155111 # Sepolia Testnet
tx_dict = {
"nonce": int("0"),
"gasPrice": int("20000000000"), # 20 Gwei
"gas": int("21000"),
"to": "0x1111111111111111111111111111111111111111",
"value": int("1000000000"), # 1 Gwei
"data": b"",
"chainId": CHAIN_ID,
}
# ==========================================
# 3. DECODE & SPLIT SIGNATURE
# ==========================================
missing_padding = len(FINAL_SIGNATURE_B64) % 4
if missing_padding:
FINAL_SIGNATURE_B64 += "=" * (4 - missing_padding)
sig_bytes = base64.b64decode(FINAL_SIGNATURE_B64)
r = int.from_bytes(sig_bytes[:32], byteorder="big")
s = int.from_bytes(sig_bytes[32:], byteorder="big")
# ==========================================
# 4. RECOVERY IDENTIFIER (V) DERIVATION
# ==========================================
chain_v_base = (CHAIN_ID * 2) + 35
# ==========================================
# 5. GENERATE UNSIGNED TX & RECOVER SENDER ADDRESS
# ==========================================
unsigned_tx = serializable_unsigned_transaction_from_dict(tx_dict)
derived_sender = None
encoded_tx = None
final_v = chain_v_base
EXPECTED_SENDER_PLACEHOLDER = "0xyour-mpc-key-address"
is_valid_expected = EXPECTED_SENDER and EXPECTED_SENDER != EXPECTED_SENDER_PLACEHOLDER
for parity in [0, 1]:
try_v = chain_v_base + parity
try:
tx_candidate = encode_transaction(unsigned_tx, vrs=(try_v, r, s))
addr = Account.recover_transaction("0x" + tx_candidate.hex())
if is_valid_expected and EXPECTED_SENDER.lower() == addr.lower():
derived_sender = addr
final_v = try_v
encoded_tx = tx_candidate
break
if not is_valid_expected and derived_sender is None:
derived_sender = addr
final_v = try_v
encoded_tx = tx_candidate
print(f"Warning: EXPECTED_SENDER not provided or is placeholder. Assuming first recovered address: {addr}")
except Exception:
continue
if encoded_tx is None:
if is_valid_expected:
raise ValueError(f"Could not recover address matching EXPECTED_SENDER: {EXPECTED_SENDER}")
else:
raise ValueError("Could not derive broadcastable transaction. Ensure signature matches payload.")
if derived_sender:
print(f"Derived Sender Address: {derived_sender}")
else:
print("Derived Sender Address: Could not recover (ensure signature matches current transaction payload)")
valid_tx_hex = "0x" + encoded_tx.hex()
print(f"Broadcastable Transaction Hex:\n{valid_tx_hex}\n")
# ==========================================
# 6. BROADCAST TO NETWORK
# ==========================================
payload = {
"jsonrpc": "2.0",
"method": "eth_sendRawTransaction",
"params": [valid_tx_hex],
"id": 1,
}
print(f"Broadcasting to {RPC_URL}...")
response = requests.post(RPC_URL, json=payload)
resp_json = response.json()
print("RPC Response:", resp_json)
if "result" in resp_json:
tx_hash = resp_json["result"]
print(f"View transaction on Sepolia Etherscan: https://sepolia.etherscan.io/tx/{tx_hash}")
EOF
python3 broadcast_eth.py
Solução de problemas comuns
invalid sender: recovery failedouinvalid transaction v, r, s values:isso ocorre se os parâmetros de transação no seu script não corresponderem exatamente ao payload que foi assinado. Verifique se os camposvalue,nonceetocorrespondem ao que foi processado na Etapa 5.insufficient funds for gas * price + value: sua transação é criptograficamente válida e foi aceita pelo nó, mas o endereço Ethereum da sua chave MPC não tem ETH de testnet suficiente para cobrir a operação. Você precisa financiar seu endereço antes de transmitir.
Bitcoin
Montagem e transmissão de transações eletrônicas do SegWit
Para transações SegWit nativas do Bitcoin (BIP 141), a assinatura MPC (r, s) bruta de 64 bytes precisa ser formatada em ASN.1 DER canônico de baixo S, anexada com 0x01 (SIGHASH_ALL) e montada com a chave pública compactada de 33 bytes na pilha de testemunhas SegWit de 2 elementos: [DER signature || 0x01, compressed public key].
Script de transmissão:
Execute o bloco a seguir para criar e executar broadcast_btc.py:
cat <<'EOF' > broadcast_btc.py
"""Assembles a signed Bitcoin Native SegWit transaction from an MPC signature using embit and broadcasts it."""
import base64
import urllib.request
from embit import ec, script, transaction
# ==========================================
# 1. INPUTS
# ==========================================
FINAL_SIGNATURE_B64 = "your-final-signature"
COMPRESSED_PUBKEY_HEX = "03deb76948c14003446a8c1d79e88fb3607c9bbc1f5143b186aa7b61d6b1facc36"
PREV_TXID_HEX = "8f594f33156993f1c980c2273dcae4a92cf2517fbc29264421395e63a63916d8"
PREV_VOUT = int("1")
RECIPIENT_SATS = int("50000")
RECIPIENT_SCRIPTPUBKEY_HEX = "0014751e76e8199196d454941c45d1b3a323f1433bd6"
CHANGE_SATS = int("149750")
CHANGE_SCRIPTPUBKEY_HEX = "0014eced05cd51d964102a20c856b09080ad620e9da2"
BROADCAST_API_URL = "https://mempool.space/testnet4/api/tx"
# ==========================================
# 2. CONVERT RAW (r, s) SIGNATURE TO CANONICAL LOW-S ASN.1 DER + SIGHASH_ALL
# ==========================================
sig_bytes = base64.b64decode(FINAL_SIGNATURE_B64)
internal_sig = ec.secp256k1.ecdsa_signature_parse_compact(sig_bytes)
ec.secp256k1.ecdsa_signature_normalize(internal_sig, internal_sig)
der_sig = ec.secp256k1.ecdsa_signature_serialize_der(internal_sig) + b"\x01" # 0x01 = SIGHASH_ALL
# ==========================================
# 3. BUILD TRANSACTION & ATTACH SEGWIT WITNESS STACK
# ==========================================
tx = transaction.Transaction(
version=2,
vin=[transaction.TransactionInput(
txid=bytes.fromhex(PREV_TXID_HEX),
vout=PREV_VOUT,
sequence=0xFFFFFFFF,
)],
vout=[
transaction.TransactionOutput(
value=RECIPIENT_SATS,
script_pubkey=script.Script(bytes.fromhex(RECIPIENT_SCRIPTPUBKEY_HEX)),
),
transaction.TransactionOutput(
value=CHANGE_SATS,
script_pubkey=script.Script(bytes.fromhex(CHANGE_SCRIPTPUBKEY_HEX)),
),
],
locktime=0,
)
pubkey_bytes = bytes.fromhex(COMPRESSED_PUBKEY_HEX)
tx.vin[0].witness = transaction.Witness([der_sig, pubkey_bytes])
signed_tx_hex = tx.serialize().hex()
print("--- Signed Bitcoin SegWit Wire Transaction Hex ---")
print(signed_tx_hex)
# ==========================================
# 4. BROADCAST TO NETWORK
# ==========================================
if BROADCAST_API_URL:
print(f"\nBroadcasting to {BROADCAST_API_URL}...")
try:
req = urllib.request.Request(
BROADCAST_API_URL,
data=signed_tx_hex.encode("utf-8"),
headers={"Content-Type": "text/plain"},
method="POST",
)
with urllib.request.urlopen(req) as resp:
txid_result = resp.read().decode("utf-8").strip()
print(f"✅ Broadcast Successful! Transaction ID (txid): {txid_result}")
print(f"Track in Mempool Explorer: https://mempool.space/testnet4/tx/{txid_result}")
except Exception as e:
print(f"Broadcast response: {e}")
EOF
python3 broadcast_btc.py
Solução de problemas comuns
mandatory-script-verify-flag-failed (Signature must be zero for failed CHECK(MULTI)SIG operation)/non-mandatory-script-verify-flag (Non-canonical DER signature):verifique se o componentesda assinatura está no formato canônico low-s (s <= N/2) e codificado corretamente em DER.bad-txns-in-belowout/bad-txns-fee-negative:o total de saídas excede o valor de entrada. Verifique se o cálculo da mudança (InputSatoshis - PaymentSatoshis - MinerFee) é estritamente positivo.
📖 Apêndice: manual operacional (consultas e inspeções)
Use esses comandos somente leitura para inspecionar o estado dos recursos a qualquer momento.
👥 1. Participantes e signatários
Inspecione os participantes e signatários na sua instância.
A. Listar todos os participantes registrados
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/signers | jq
B. Ver detalhes de um participante específico
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/signers/signer-alice | jq
📜 2. Policy Engine
Inspecione políticas e pacotes de confiança.
A. Acessar o pacote de confiança do autor da política
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policyAuthorTrustBundle | jq
B. Listar todas as políticas
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies | jq
C. Ver detalhes de uma política específica
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/policyEngine/policies/ethereum-transfer-policy | jq
🔑 3. Chaves e KeyRings
Inspecionar keyrings e chaves.
A. Listar todos os KeyRings
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings | jq
B. Listar todas as chaves em um KeyRing
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys | jq
C. Receber o status de uma chave distribuída específica (status de DKG)
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key | jq
📝 4. Propostas (operações de assinatura)
Inspecione as propostas e o status de assinatura.
A. Listar todas as propostas de uma chave
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals | jq
B. Ver detalhes ou status de uma proposta específica
curl
curl -H "Authorization: Bearer $(gcloud auth application-default print-access-token)" \
-H "X-Goog-User-Project: my-project" \
https://67317436-0f29-ba9e-9146-d11c0bd8df9b.us-central1.mpc.goog/v1alpha1/projects/my-project/locations/us-central1/instances/mpc-unit-bob-123/mpc/keyRings/my-key-ring/keys/my-key/proposals/my-proposal | jq