1Z0-1127-25 Using OCI Generative AI Service Practice Question
Which authentication method should be used to securely call the OCI Generative AI API from a microservice running on OCI Compute?
⚠ Common exam trap
A common misconception is that instance principal authentication is the default or only secure method for OCI Compute instances, but the exam trap here is that instance principal requires dynamic group configuration and is not the direct authentication method for the OCI API; the API signing key is the explicit, universally supported method for programmatic API calls from any client, including a Compute instance.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
OCI API signing key
The OCI API signing key method uses a pre-generated RSA key pair to sign each HTTP request cryptographically, which is the standard and most secure way to authenticate calls to OCI services, including the Generative AI API, from a microservice running on OCI Compute. This method does not rely on external identity providers or token exchanges, making it ideal for server-to-server communication within OCI.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
OAuth 2.0 client credentials
Why it's wrong here
OAuth is possible but less common for OCI API calls; API key is standard.
- ✗
SAML 2.0 assertion
Why it's wrong here
SAML is used for federation, not direct API authentication.
- ✗
Instance principal
Why it's wrong here
Instance principal is for Compute instances to call services without managing keys, but for a microservice, an API key is more portable.
- ✓
OCI API signing key
Why this is correct
OCI API signing key (a key pair) is the standard method for authenticating API requests.
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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