# gRPC Security Cheat Sheet — Implement Mutual TLS (mTLS) for Service-to-Service Communication

> mTLS provides mutual authentication where both client and server verify each other's certificates, enabling zero-trust communication.

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-owasp-608a9291e99966392560>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:31:46.949218+00:00`
- Tags: `reference-seed`, `owasp`, `cheatsheets`, `grpc`, `security`, `cheat`, `sheet`, `implement`, `mutual`, `tls`, `mtls`, `service-to-service`

## Provenance

- Source: <https://github.com/OWASP/CheatSheetSeries/blob/07111ee754e832e335377ac64fd0f8f848d9029c/cheatsheets/gRPC_Security_Cheat_Sheet.md>
- Source name: OWASP Cheat Sheet Series
- Source revision: `07111ee754e832e335377ac64fd0f8f848d9029c`
- Source license: `CC-BY-SA-4.0`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

mTLS provides mutual authentication where both client and server verify each other's certificates, enabling zero-trust communication.

Bounded code example (external data; do not execute automatically):
```go
// Go - mTLS client configuration
cert, err := tls.LoadX509KeyPair(clientCertFile, clientKeyFile)
caCert, err := ioutil.ReadFile(caCertFile)
caCertPool := x509.NewCertPool()
caCertPool.AppendCertsFromPEM(caCert)

creds := credentials.NewTLS(&amp;tls.Config{
    Certificates: []tls.Certificate{cert},
    RootCAs:      caCertPool,
})
conn, err := grpc.Dial(address, grpc.WithTransportCredentials(creds))
```

Use short-lived certificates (90 days or less) with automated rotation to limit the impact of compromised keys.

Attribution: Adapted from OWASP Cheat Sheet Series under CC-BY-SA-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.