feat(sdk-hmac): add v4 canonical preimage construction

[MohammedRyaan786]

TICKET: CAAS-660

This pull request introduces a new v4 HMAC authentication module, adds utility functions for hashing and HMAC operations, and refactors the existing code to support the new authentication scheme. The changes are grouped into three main themes: new v4 authentication functionality, utility enhancements, and integration/refactoring of existing code.

New v4 authentication functionality:

• Added hmacv4.ts module implementing v4 authentication, including canonical preimage construction, body hashing, HMAC signature calculation, header generation, response verification, and support for proxy headers.
• Extended types.ts with new interfaces for v4 authentication options, headers, and verification results, enabling type-safe usage of the new v4 methods.

Utility enhancements:

• Added util.ts with functions for SHA256 hashing (sha256Hex), HMAC-SHA256 (hmacSha256), HTTP method normalization, path extraction, and timestamp calculation, supporting both Node.js and browser environments.

Integration and refactoring:

• Refactored hmac.ts to use the new hmacSha256 utility function instead of directly calling createHmac, improving code reuse and consistency. [1] [2] [3]
• Updated index.ts to export the new hmacv4, util, and extended types, making all new functionality available to consumers of the SDK.

[Copilot]

Pull request overview

Adds a new v4 HMAC signing/verification implementation to @bitgo/sdk-hmac, including canonical preimage construction (newline-delimited fields + trailing newline), body hashing, and request/response helper utilities.

Changes:

• Introduces hmacv4 module for v4 preimage construction, request header generation, and response verification.
• Adds shared crypto/time helpers in util.ts and refactors v2/v3 calculateHMAC to use the shared HMAC helper.
• Adds comprehensive unit tests covering v4 signing/verification behavior and helper functions.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
modules/sdk-hmac/src/hmacv4.ts	New v4 signing + verification implementation and proxy header helpers
modules/sdk-hmac/src/util.ts	New shared SHA256/HMAC primitives + method normalization + timestamp helper
modules/sdk-hmac/src/types.ts	Adds v4-specific option/result types and expands AuthVersion union
modules/sdk-hmac/src/index.ts	Exports new v4 module and util helpers from package entrypoint
modules/sdk-hmac/src/hmac.ts	Refactors v2/v3 HMAC primitive to call shared hmacSha256()
modules/sdk-hmac/test/hmacv4.ts	New unit test suite for v4 logic and util helpers

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

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