grpc node mutual auth failed when uses secp256k1 with the ECDSA algorithm

### Problem description
I've been using a self generated **RSA** Certificate Authority to sign my server and clients certificates and so far [grpc node mutual authentication](https://github.com/vulnsystem/OpenssLabs/tree/main/grpc-client-auth) worked fine.

Following the same why, I'm trying to use secp256k1 with the ECDSA algorithm, assmuming that the key of **BTC** or **ETH** will be used grpc authentication directly. Unfortunately I cannot get right output.

### Reproduction steps
All the following contents and steps can been found from the [repository](https://github.com/vulnsystem/OpenssLabs/tree/main/grpc-auth-secp256k1)
1. To generate server and client's EC secp256k1 private key and TLS certificates with [gen.sh](https://github.com/vulnsystem/OpenssLabs/blob/main/grpc-auth-secp256k1/credentials/gen.sh).
```
# 1. Generate EC private key and self-signed certificate
openssl ecparam -genkey -out ca.key -name secp256k1
openssl req -x509 -new -key ca.key -out ca.cert -subj "/C=FR/ST=Occitanie/L=Toulouse/O=Tech School/OU=Education/CN=*.techschool.guru/emailAddress=root.guru@gmail.com"

echo "CA's self-signed certificate"
openssl x509 -in ca.cert -noout -text

# 2. Generate web server's private key and certificate signing request (EC)
openssl ecparam -genkey -out server.key -name secp256k1
openssl req -key server.key -new -out server.req -subj "/C=FR/ST=Ile de France/L=Paris/O=PC Book/OU=Computer/CN=*.pcbook.com/emailAddress=server@gmail.com"

# 3. Use CA's private key to sign web server's CSR and get back the signed certificate
openssl x509 -req -in server.req -days 60 -CA ca.cert -CAkey ca.key -CAcreateserial -out server.cert -extfile server.ext

echo "Server's signed certificate"
openssl x509 -in server.cert -noout -text

# 4. Generate client's private key and certificate signing request (EC)
openssl ecparam -genkey -out client.key -name secp256k1
openssl req -key client.key -new -out client.req -subj "/C=FR/ST=Alsace/L=Strasbourg/O=PC Client/OU=Computer/CN=*.client.com/emailAddress=client@gmail.com"

# 5. Use CA's private key to sign client's CSR and get back the signed certificate
openssl x509 -req -in client.req -days 60 -CA ca.cert -CAkey ca.key -CAcreateserial -out client.cert -extfile client.ext

echo "Client's signed certificate"
openssl x509 -in client.cert -noout -text

# 6. To verify the server certificate aginst by root CA
echo "server's certificate verification"
openssl verify -show_chain -CAfile ca.cert server.cert

# 7. To verify the client certificate aginst by root CA.
echo "client's certificate verification"
openssl verify -show_chain -CAfile ca.cert client.cert
```
2. Implement server-side Auth in [greeter_server.js](https://github.com/vulnsystem/OpenssLabs/blob/main/grpc-auth-secp256k1/greeter_server.js)
```
function main() {
var server = new grpc.Server();

server.addService(hello_proto.Greeter.service, {sayHello: sayHello});
server.bindAsync('0.0.0.0:50051', grpc.ServerCredentials.createSsl(
fs.readFileSync('./credentials/ca.cert'),
[{
cert_chain: fs.readFileSync('./credentials/server.cert'),
private_key: fs.readFileSync('./credentials/server.key')
}],
true
), () => {
server.start();
});
}
```
3. Implement client-side Auth in [greeter_client.js](https://github.com/vulnsystem/OpenssLabs/blob/main/grpc-auth-secp256k1/greeter_client.js)
```
var client = new hello_proto.Greeter(target,
grpc.credentials.createSsl(fs.readFileSync('./credentials/ca.cert'),
fs.readFileSync('./credentials/client.key'),
fs.readFileSync('./credentials/client.cert')));
```
4. Try it out!
```shell
npm install
node greeter_server.js
node greeter_client.js
```
5. The server started successfully and Error output from client is:
```
/grpc-auth-secp256k1/greeter_client.js:57
console.log('Greeting:', response.message); ^

TypeError: Cannot read property 'message' of undefined
at Object.callback (grpc-auth-secp256k1/greeter_client.js:57:39)
at Object.onReceiveStatus (grpc-auth-secp256k1/node_modules/@grpc/grpc-js/build/src/client.js:176:36)
at Object.onReceiveStatus (grpc-auth-secp256k1/node_modules/@grpc/grpc-js/build/src/client-interceptors.js:342:141)
at Object.onReceiveStatus OpenssLabs/grpc-auth-secp256k1/node_modules/@grpc/grpc-js/build/src/client-interceptors.js:305:181)
at grpc-auth-secp256k1/node_modules/@grpc/grpc-js/build/src/call-stream.js:124:78
at processTicksAndRejections (internal/process/task_queues.js:75:11)
```

The grpc node mutual authentication is successful with [RSA Certificate](https://github.com/vulnsystem/OpenssLabs/tree/main/grpc-client-auth) , but failed with **secp256k1**.

### Environment
- OS [Ubuntu 18.04 amd64]
- Node version [v14.16.1]
- Node installation method [nvm]
- Package name and version [@grpc/grpc-js : 1.1.0]
- Authentication mode: SSL/TLS
- Signature algorithm: ecdsa-withsha256
- Key generate type: **secp256k1**
- Source code: dynamic_codegen from grpc node examples

### Additional context
No

### Question
1. How to show the grpc TLS handshake informaiton like openssl debug?
2. Is there any clue to fix the problem?