Encoding in OAuth 2.0: PKCE, State Params, and Base64URL Tokens
OAuth 2.0 uses Base64URL encoding for tokens, code challenges, and state parameters. Learn the exact encoding steps for PKCE and how to decode tokens safely.
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Tags: security, oauth, encoding
Encoding in OAuth 2.0: PKCE, State Params, and Base64URL Tokens OAuth 2.0 uses encoding at multiple points in its flows, each for a distinct purpose. Understanding which encoding is used where — and why — helps you implement OAuth correctly and avoid subtle security mistakes that developers make when they do not understand what the encoding is doing. This article covers the encoding mechanics of the Authorization Code flow with PKCE, state parameters, token formats, and the token endpoint request. -------------|-----------| | | | | | | | (padding) | Omitted | The result is a string that can appear in a URL without percent-encoding. This is used for JWT tokens, OAuth authorization codes, and PKCE code challenges. You can verify this with a Base64 encoder: encode any string, then note which…
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