AWS Access Key类比公钥私钥的合理性及CLI配置疑问

Can Access Key ID be compared to a public key, and Secret Access Key to a private key? #

Absolutely, that’s a spot-on analogy to grasp how these credentials function! Here’s the breakdown:

• The Access Key ID acts just like a public key: it’s a non-sensitive identifier meant to be shared (or at least visible) to tell AWS who’s making the request. It doesn’t grant access on its own—AWS uses it to look up your account and linked permissions.
• The Secret Access Key mirrors a private key perfectly: it’s never meant to be shared, exposed publicly, or transmitted over untrusted networks. This is what signs your programmatic API requests. AWS uses your Access Key ID to retrieve the matching secret stored on their end, then verifies that the request was sent by you and hasn’t been tampered with in transit.

A quick technical note: AWS uses HMAC (Hash-Based Message Authentication Codes) instead of asymmetric encryption like traditional public/private key pairs, but the core logic of "public identifier + private secret for verification" is identical.

Why does AWS CLI require both in ~/.aws/credentials? #

The CLI needs both credentials for two interdependent, critical reasons:

1. Identify the requester: The Access Key ID tells AWS which account and IAM entity (user/role) is initiating the request. Without this, AWS has no way to know who to authenticate or apply permissions to.
2. Verify request authenticity: The Secret Access Key generates a unique signature for every API request the CLI sends. AWS recalculates this signature using the secret linked to your Access Key ID—if the signatures match, it confirms the request is legitimate and unaltered.

If you only provided the Access Key ID, anyone could forge requests using your identifier, and AWS couldn’t distinguish real requests from fakes. If you only provided the Secret Access Key, AWS wouldn’t know which account’s secret to use for verification, so the request would fail instantly.

内容的提问来源于stack exchange，提问作者David