Allow strict base64 decoding #259
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By default base64 decoder works in non-strict mode which allows tweaking signatures having padding without failing validation. This creates a potential problem if application treats token value as an identifier. For example ES256 signature has length of 64 bytes and two padding symbols (stripped by default). Therefore its base64-encoded value can only end with A, Q, g and w. In non-strict mode last symbol could be tweaked resulting in 16 distinct token values having the same signature and passing validation. This change adds backward-compatible global config variable DecodeStrict (similar to existing DecodePaddingAllowed) that enables strict base64 decoder mode. See also golang/go#15656. Signed-off-by: Alexander Yastrebov <yastrebov.alex@gmail.com>
oxisto
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Dec 2, 2022
|
I made it backward-compatible but IMO this could be true by default. Let me know what you think, I'll update the PR if needed. |
I would keep it as false by default for this version and we can think about making it true for v5. |
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…v4.5.0 (#75) This PR contains the following updates: | Package | Type | Update | Change | |---|---|---|---| | [github.com/golang-jwt/jwt/v4](https://togithub.com/golang-jwt/jwt) | require | minor | `v4.4.3` -> `v4.5.0` | --- ### Release Notes <details> <summary>golang-jwt/jwt</summary> ### [`v4.5.0`](https://togithub.com/golang-jwt/jwt/releases/tag/v4.5.0) [Compare Source](https://togithub.com/golang-jwt/jwt/compare/v4.4.3...v4.5.0) #### What's Changed - Allow strict base64 decoding by [@​AlexanderYastrebov](https://togithub.com/AlexanderYastrebov) in [golang-jwt/jwt#259 **Full Changelog**: golang-jwt/jwt@v4.4.3...v4.5.0 </details> --- ### Configuration 📅 **Schedule**: Branch creation - "before 3am on Monday" (UTC), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Enabled. ♻ **Rebasing**: Whenever PR is behind base branch, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box <!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzNC4xMDAuMSIsInVwZGF0ZWRJblZlciI6IjM0LjEwMC4xIn0=--> Co-authored-by: mend-for-github-com[bot] <50673670+mend-for-github-com[bot]@users.noreply.github.com>
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By default base64 decoder works in non-strict mode which allows tweaking signatures having padding without failing validation. This creates a potential problem if application treats token value as an identifier. For example ES256 signature has length of 64 bytes and two padding symbols (stripped by default). Therefore its base64-encoded value can only end with A, Q, g and w. In non-strict mode last symbol could be tweaked resulting in 16 distinct token values having the same signature and passing validation. This change adds backward-compatible global config variable DecodeStrict (similar to existing DecodePaddingAllowed) that enables strict base64 decoder mode. See also golang/go#15656. Signed-off-by: Alexander Yastrebov <yastrebov.alex@gmail.com>
oxisto
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Mar 29, 2023
By default base64 decoder works in non-strict mode which allows tweaking signatures having padding without failing validation. This creates a potential problem if application treats token value as an identifier. For example ES256 signature has length of 64 bytes and two padding symbols (stripped by default). Therefore its base64-encoded value can only end with A, Q, g and w. In non-strict mode last symbol could be tweaked resulting in 16 distinct token values having the same signature and passing validation. This change adds backward-compatible global config variable DecodeStrict (similar to existing DecodePaddingAllowed) that enables strict base64 decoder mode. See also golang/go#15656. Signed-off-by: Alexander Yastrebov <yastrebov.alex@gmail.com>
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By default base64 decoder works in non-strict mode which allows tweaking signatures having padding without failing validation.
This creates a potential problem if application treats token value as an identifier.
For example ES256 signature has length of 64 bytes and two padding symbols (stripped by default). Therefore its base64-encoded value can only end with A, Q, g and w. In non-strict mode last symbol could be tweaked resulting in 16 distinct token values having the same signature and passing validation.
This change adds backward-compatible global config variable DecodeStrict (similar to existing DecodePaddingAllowed) that enables strict base64 decoder mode.
See also golang/go#15656.
Signed-off-by: Alexander Yastrebov yastrebov.alex@gmail.com