Principle:Cohere ai Cohere python AWS SigV4 Authentication
| Property | Value |
|---|---|
| Type | Principle |
| Domain | Authentication, AWS Integration, Request Signing |
| Source | Cohere Python SDK |
| Last Updated | 2026-02-15 |
| Implemented By | Implementation:Cohere_ai_Cohere_python_SigV4_Request_Signing |
Overview
An authentication mechanism for signing API requests to AWS services using Signature Version 4 (SigV4) credentials.
Description
AWS SigV4 Authentication is the process of cryptographically signing HTTP requests to AWS services using access keys. When using Cohere models deployed on AWS Bedrock, requests must be authenticated with SigV4 instead of Cohere API keys. The SDK integrates SigV4 signing via httpx event hooks — the request hook intercepts outgoing requests, rewrites the URL to the Bedrock endpoint, removes model/stream from the body, and applies SigV4 signing headers using boto3/botocore credentials.
Usage
Configure AWS credentials (via explicit parameters or boto3 default credential chain) when initializing BedrockClientV2. The SigV4 signing is automatic and transparent.
- Provide aws_access_key, aws_secret_key, and aws_region explicitly, or
- Rely on the boto3 default credential chain (environment variables,
~/.aws/credentials, IAM role) - All subsequent API calls are automatically signed — no manual signing required
Theoretical Basis
SigV4 computes an HMAC-SHA256 signature over a canonical representation of the HTTP request (method, URL, headers, body hash). The signature proves the requester has the secret key without transmitting it. The SDK uses botocore.auth.SigV4Auth to compute signatures per the AWS specification.
- The canonical request format normalizes headers, query parameters, and body for consistent signing
- Time-limited signatures prevent replay attacks
- The credential scope binds signatures to specific regions and services