├── LICENSE └── README.md /LICENSE: -------------------------------------------------------------------------------- 1 | Mozilla Public License Version 2.0 2 | ================================== 3 | 4 | 1. Definitions 5 | -------------- 6 | 7 | 1.1. "Contributor" 8 | means each individual or legal entity that creates, contributes to 9 | the creation of, or owns Covered Software. 10 | 11 | 1.2. "Contributor Version" 12 | means the combination of the Contributions of others (if any) used 13 | by a Contributor and that particular Contributor's Contribution. 14 | 15 | 1.3. "Contribution" 16 | means Covered Software of a particular Contributor. 17 | 18 | 1.4. "Covered Software" 19 | means Source Code Form to which the initial Contributor has attached 20 | the notice in Exhibit A, the Executable Form of such Source Code 21 | Form, and Modifications of such Source Code Form, in each case 22 | including portions thereof. 23 | 24 | 1.5. "Incompatible With Secondary Licenses" 25 | means 26 | 27 | (a) that the initial Contributor has attached the notice described 28 | in Exhibit B to the Covered Software; or 29 | 30 | (b) that the Covered Software was made available under the terms of 31 | version 1.1 or earlier of the License, but not also under the 32 | terms of a Secondary License. 33 | 34 | 1.6. "Executable Form" 35 | means any form of the work other than Source Code Form. 36 | 37 | 1.7. "Larger Work" 38 | means a work that combines Covered Software with other material, in 39 | a separate file or files, that is not Covered Software. 40 | 41 | 1.8. "License" 42 | means this document. 43 | 44 | 1.9. "Licensable" 45 | means having the right to grant, to the maximum extent possible, 46 | whether at the time of the initial grant or subsequently, any and 47 | all of the rights conveyed by this License. 48 | 49 | 1.10. "Modifications" 50 | means any of the following: 51 | 52 | (a) any file in Source Code Form that results from an addition to, 53 | deletion from, or modification of the contents of Covered 54 | Software; or 55 | 56 | (b) any new file in Source Code Form that contains any Covered 57 | Software. 58 | 59 | 1.11. "Patent Claims" of a Contributor 60 | means any patent claim(s), including without limitation, method, 61 | process, and apparatus claims, in any patent Licensable by such 62 | Contributor that would be infringed, but for the grant of the 63 | License, by the making, using, selling, offering for sale, having 64 | made, import, or transfer of either its Contributions or its 65 | Contributor Version. 66 | 67 | 1.12. "Secondary License" 68 | means either the GNU General Public License, Version 2.0, the GNU 69 | Lesser General Public License, Version 2.1, the GNU Affero General 70 | Public License, Version 3.0, or any later versions of those 71 | licenses. 72 | 73 | 1.13. "Source Code Form" 74 | means the form of the work preferred for making modifications. 75 | 76 | 1.14. "You" (or "Your") 77 | means an individual or a legal entity exercising rights under this 78 | License. For legal entities, "You" includes any entity that 79 | controls, is controlled by, or is under common control with You. For 80 | purposes of this definition, "control" means (a) the power, direct 81 | or indirect, to cause the direction or management of such entity, 82 | whether by contract or otherwise, or (b) ownership of more than 83 | fifty percent (50%) of the outstanding shares or beneficial 84 | ownership of such entity. 85 | 86 | 2. License Grants and Conditions 87 | -------------------------------- 88 | 89 | 2.1. Grants 90 | 91 | Each Contributor hereby grants You a world-wide, royalty-free, 92 | non-exclusive license: 93 | 94 | (a) under intellectual property rights (other than patent or trademark) 95 | Licensable by such Contributor to use, reproduce, make available, 96 | modify, display, perform, distribute, and otherwise exploit its 97 | Contributions, either on an unmodified basis, with Modifications, or 98 | as part of a Larger Work; and 99 | 100 | (b) under Patent Claims of such Contributor to make, use, sell, offer 101 | for sale, have made, import, and otherwise transfer either its 102 | Contributions or its Contributor Version. 103 | 104 | 2.2. Effective Date 105 | 106 | The licenses granted in Section 2.1 with respect to any Contribution 107 | become effective for each Contribution on the date the Contributor first 108 | distributes such Contribution. 109 | 110 | 2.3. Limitations on Grant Scope 111 | 112 | The licenses granted in this Section 2 are the only rights granted under 113 | this License. No additional rights or licenses will be implied from the 114 | distribution or licensing of Covered Software under this License. 115 | Notwithstanding Section 2.1(b) above, no patent license is granted by a 116 | Contributor: 117 | 118 | (a) for any code that a Contributor has removed from Covered Software; 119 | or 120 | 121 | (b) for infringements caused by: (i) Your and any other third party's 122 | modifications of Covered Software, or (ii) the combination of its 123 | Contributions with other software (except as part of its Contributor 124 | Version); or 125 | 126 | (c) under Patent Claims infringed by Covered Software in the absence of 127 | its Contributions. 128 | 129 | This License does not grant any rights in the trademarks, service marks, 130 | or logos of any Contributor (except as may be necessary to comply with 131 | the notice requirements in Section 3.4). 132 | 133 | 2.4. Subsequent Licenses 134 | 135 | No Contributor makes additional grants as a result of Your choice to 136 | distribute the Covered Software under a subsequent version of this 137 | License (see Section 10.2) or under the terms of a Secondary License (if 138 | permitted under the terms of Section 3.3). 139 | 140 | 2.5. Representation 141 | 142 | Each Contributor represents that the Contributor believes its 143 | Contributions are its original creation(s) or it has sufficient rights 144 | to grant the rights to its Contributions conveyed by this License. 145 | 146 | 2.6. Fair Use 147 | 148 | This License is not intended to limit any rights You have under 149 | applicable copyright doctrines of fair use, fair dealing, or other 150 | equivalents. 151 | 152 | 2.7. Conditions 153 | 154 | Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted 155 | in Section 2.1. 156 | 157 | 3. Responsibilities 158 | ------------------- 159 | 160 | 3.1. Distribution of Source Form 161 | 162 | All distribution of Covered Software in Source Code Form, including any 163 | Modifications that You create or to which You contribute, must be under 164 | the terms of this License. You must inform recipients that the Source 165 | Code Form of the Covered Software is governed by the terms of this 166 | License, and how they can obtain a copy of this License. You may not 167 | attempt to alter or restrict the recipients' rights in the Source Code 168 | Form. 169 | 170 | 3.2. Distribution of Executable Form 171 | 172 | If You distribute Covered Software in Executable Form then: 173 | 174 | (a) such Covered Software must also be made available in Source Code 175 | Form, as described in Section 3.1, and You must inform recipients of 176 | the Executable Form how they can obtain a copy of such Source Code 177 | Form by reasonable means in a timely manner, at a charge no more 178 | than the cost of distribution to the recipient; and 179 | 180 | (b) You may distribute such Executable Form under the terms of this 181 | License, or sublicense it under different terms, provided that the 182 | license for the Executable Form does not attempt to limit or alter 183 | the recipients' rights in the Source Code Form under this License. 184 | 185 | 3.3. Distribution of a Larger Work 186 | 187 | You may create and distribute a Larger Work under terms of Your choice, 188 | provided that You also comply with the requirements of this License for 189 | the Covered Software. If the Larger Work is a combination of Covered 190 | Software with a work governed by one or more Secondary Licenses, and the 191 | Covered Software is not Incompatible With Secondary Licenses, this 192 | License permits You to additionally distribute such Covered Software 193 | under the terms of such Secondary License(s), so that the recipient of 194 | the Larger Work may, at their option, further distribute the Covered 195 | Software under the terms of either this License or such Secondary 196 | License(s). 197 | 198 | 3.4. Notices 199 | 200 | You may not remove or alter the substance of any license notices 201 | (including copyright notices, patent notices, disclaimers of warranty, 202 | or limitations of liability) contained within the Source Code Form of 203 | the Covered Software, except that You may alter any license notices to 204 | the extent required to remedy known factual inaccuracies. 205 | 206 | 3.5. Application of Additional Terms 207 | 208 | You may choose to offer, and to charge a fee for, warranty, support, 209 | indemnity or liability obligations to one or more recipients of Covered 210 | Software. However, You may do so only on Your own behalf, and not on 211 | behalf of any Contributor. You must make it absolutely clear that any 212 | such warranty, support, indemnity, or liability obligation is offered by 213 | You alone, and You hereby agree to indemnify every Contributor for any 214 | liability incurred by such Contributor as a result of warranty, support, 215 | indemnity or liability terms You offer. You may include additional 216 | disclaimers of warranty and limitations of liability specific to any 217 | jurisdiction. 218 | 219 | 4. Inability to Comply Due to Statute or Regulation 220 | --------------------------------------------------- 221 | 222 | If it is impossible for You to comply with any of the terms of this 223 | License with respect to some or all of the Covered Software due to 224 | statute, judicial order, or regulation then You must: (a) comply with 225 | the terms of this License to the maximum extent possible; and (b) 226 | describe the limitations and the code they affect. Such description must 227 | be placed in a text file included with all distributions of the Covered 228 | Software under this License. Except to the extent prohibited by statute 229 | or regulation, such description must be sufficiently detailed for a 230 | recipient of ordinary skill to be able to understand it. 231 | 232 | 5. Termination 233 | -------------- 234 | 235 | 5.1. The rights granted under this License will terminate automatically 236 | if You fail to comply with any of its terms. However, if You become 237 | compliant, then the rights granted under this License from a particular 238 | Contributor are reinstated (a) provisionally, unless and until such 239 | Contributor explicitly and finally terminates Your grants, and (b) on an 240 | ongoing basis, if such Contributor fails to notify You of the 241 | non-compliance by some reasonable means prior to 60 days after You have 242 | come back into compliance. Moreover, Your grants from a particular 243 | Contributor are reinstated on an ongoing basis if such Contributor 244 | notifies You of the non-compliance by some reasonable means, this is the 245 | first time You have received notice of non-compliance with this License 246 | from such Contributor, and You become compliant prior to 30 days after 247 | Your receipt of the notice. 248 | 249 | 5.2. If You initiate litigation against any entity by asserting a patent 250 | infringement claim (excluding declaratory judgment actions, 251 | counter-claims, and cross-claims) alleging that a Contributor Version 252 | directly or indirectly infringes any patent, then the rights granted to 253 | You by any and all Contributors for the Covered Software under Section 254 | 2.1 of this License shall terminate. 255 | 256 | 5.3. In the event of termination under Sections 5.1 or 5.2 above, all 257 | end user license agreements (excluding distributors and resellers) which 258 | have been validly granted by You or Your distributors under this License 259 | prior to termination shall survive termination. 260 | 261 | ************************************************************************ 262 | * * 263 | * 6. Disclaimer of Warranty * 264 | * ------------------------- * 265 | * * 266 | * Covered Software is provided under this License on an "as is" * 267 | * basis, without warranty of any kind, either expressed, implied, or * 268 | * statutory, including, without limitation, warranties that the * 269 | * Covered Software is free of defects, merchantable, fit for a * 270 | * particular purpose or non-infringing. The entire risk as to the * 271 | * quality and performance of the Covered Software is with You. * 272 | * Should any Covered Software prove defective in any respect, You * 273 | * (not any Contributor) assume the cost of any necessary servicing, * 274 | * repair, or correction. This disclaimer of warranty constitutes an * 275 | * essential part of this License. No use of any Covered Software is * 276 | * authorized under this License except under this disclaimer. * 277 | * * 278 | ************************************************************************ 279 | 280 | ************************************************************************ 281 | * * 282 | * 7. Limitation of Liability * 283 | * -------------------------- * 284 | * * 285 | * Under no circumstances and under no legal theory, whether tort * 286 | * (including negligence), contract, or otherwise, shall any * 287 | * Contributor, or anyone who distributes Covered Software as * 288 | * permitted above, be liable to You for any direct, indirect, * 289 | * special, incidental, or consequential damages of any character * 290 | * including, without limitation, damages for lost profits, loss of * 291 | * goodwill, work stoppage, computer failure or malfunction, or any * 292 | * and all other commercial damages or losses, even if such party * 293 | * shall have been informed of the possibility of such damages. This * 294 | * limitation of liability shall not apply to liability for death or * 295 | * personal injury resulting from such party's negligence to the * 296 | * extent applicable law prohibits such limitation. Some * 297 | * jurisdictions do not allow the exclusion or limitation of * 298 | * incidental or consequential damages, so this exclusion and * 299 | * limitation may not apply to You. * 300 | * * 301 | ************************************************************************ 302 | 303 | 8. Litigation 304 | ------------- 305 | 306 | Any litigation relating to this License may be brought only in the 307 | courts of a jurisdiction where the defendant maintains its principal 308 | place of business and such litigation shall be governed by laws of that 309 | jurisdiction, without reference to its conflict-of-law provisions. 310 | Nothing in this Section shall prevent a party's ability to bring 311 | cross-claims or counter-claims. 312 | 313 | 9. Miscellaneous 314 | ---------------- 315 | 316 | This License represents the complete agreement concerning the subject 317 | matter hereof. If any provision of this License is held to be 318 | unenforceable, such provision shall be reformed only to the extent 319 | necessary to make it enforceable. Any law or regulation which provides 320 | that the language of a contract shall be construed against the drafter 321 | shall not be used to construe this License against a Contributor. 322 | 323 | 10. Versions of the License 324 | --------------------------- 325 | 326 | 10.1. New Versions 327 | 328 | Mozilla Foundation is the license steward. Except as provided in Section 329 | 10.3, no one other than the license steward has the right to modify or 330 | publish new versions of this License. Each version will be given a 331 | distinguishing version number. 332 | 333 | 10.2. Effect of New Versions 334 | 335 | You may distribute the Covered Software under the terms of the version 336 | of the License under which You originally received the Covered Software, 337 | or under the terms of any subsequent version published by the license 338 | steward. 339 | 340 | 10.3. Modified Versions 341 | 342 | If you create software not governed by this License, and you want to 343 | create a new license for such software, you may create and use a 344 | modified version of this License if you rename the license and remove 345 | any references to the name of the license steward (except to note that 346 | such modified license differs from this License). 347 | 348 | 10.4. Distributing Source Code Form that is Incompatible With Secondary 349 | Licenses 350 | 351 | If You choose to distribute Source Code Form that is Incompatible With 352 | Secondary Licenses under the terms of this version of the License, the 353 | notice described in Exhibit B of this License must be attached. 354 | 355 | Exhibit A - Source Code Form License Notice 356 | ------------------------------------------- 357 | 358 | This Source Code Form is subject to the terms of the Mozilla Public 359 | License, v. 2.0. If a copy of the MPL was not distributed with this 360 | file, You can obtain one at http://mozilla.org/MPL/2.0/. 361 | 362 | If it is not possible or desirable to put the notice in a particular 363 | file, then You may include the notice in a location (such as a LICENSE 364 | file in a relevant directory) where a recipient would be likely to look 365 | for such a notice. 366 | 367 | You may add additional accurate notices of copyright ownership. 368 | 369 | Exhibit B - "Incompatible With Secondary Licenses" Notice 370 | --------------------------------------------------------- 371 | 372 | This Source Code Form is "Incompatible With Secondary Licenses", as 373 | defined by the Mozilla Public License, v. 2.0. 374 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # WebCrypto Key Management API Extension 2 | 3 | ## Authors: 4 | 5 | - Kyle Den Hartog (Brave) 6 | 7 | ## Participate 8 | - [Repo Issues](https://github.com/brave-experiments/hardware-backed-webcrypto/issues) 9 | 10 | ## Introduction 11 | 12 | As cryptographic key management is becoming more necessary on the Web for security purposes it has meant that many wallets, extensions, and browser features need to re-implement key management for various features in the Web platform. Furthermore, many sites rely upon cryptographic operations, but often need hardware backed key storage or do not want to expose the cryptographic keys to site scripts and utilize site storage for risk of key theft. This has meant that there's a lot of re-implementation of basic cryptographic operations in many places that all encounter their own various tradeoffs. The purpose of this WebCrypto extension is to add low level key management API so that it would be possible to have hardware backed keys as a low level primitive. Additionally, this would allow for a purely browser managed software cryptographic implementation for commonly used algorithms. From there various features on the web such as wallets and browser APIs like WebAuthn Level 3 could be built upon this generalized key management layer. 13 | 14 | ## Goals [or Motivating Use Cases, or Scenarios] 15 | 16 | The overarching meta-goal of this proposal is to abstract key management away from application logic and encapsulate it within the WebCrypto API. Some specific use cases where this would be useful include: 17 | 18 | - Cryptocurrency Wallet Extensions 19 | - Digital Credential Wallet Extensions 20 | - Browser Managed digital credential wallets 21 | - Software defined passkey authenticators managed by a Browser 22 | - Device Bound Session Credentials 23 | 24 | ## Non-goals 25 | 26 | - Key synchronization 27 | 28 | While key synchronization is a key feature to further enhance the use cases and features described above, it's not immediately necessary for the functionality of this WebCrypto interface extension. It's highly likely though that this moves in parallel to this given the growing importance for key synchronization in order to handle recovery flows more easily. 29 | 30 | One example of a parallel piece of work for key synchronization that may be integrated with this work in the future is happening at the FIDO Alliance in the [Credential Provider Special Interest Group](https://www.youtube.com/watch?v=Mje6J2IMRTY). 31 | 32 | ## Key Management API Extension 33 | 34 | [For each related element of the proposed solution - be it an additional JS method, a new object, a new element, a new concept etc., create a section which briefly describes it.] 35 | 36 | ### Create a hardware backed key via WebCrypto API 37 | ```js 38 | let keyPair = await window.crypto.subtle.generateKey( 39 | { 40 | name: "ECDSA", 41 | namedCurve: "P-256", 42 | }, 43 | extractable: false, 44 | bindings: { 45 | hardwareBound: true, 46 | originBindings: ["example.com"], 47 | identifier: "123ABC", 48 | updatable: true 49 | }, 50 | ["sign", "verify"], 51 | ); 52 | ``` 53 | 54 | In this scenario, we're suggesting a modification to the `extractable` property such that the old method where a boolean was provided would imply the same usage as before this extension. This allows for the API to be an opt in functionality for browsers. The additional `bindings` property allows for initial configurations for the key to be set and will become additional properties of the `CryptoKey` object. Here's some brief explanations of the different additional properties: 55 | 56 | - `hardwareBound`: This one determines if the CryptoKey will be hardware bound. In the event that the `hardwareBound` is set to true, but extractable is set to false an error would be returned. The reason this is an optional configuration parameter rather than assuming whenever a `bindings` is include the CryptoKey will be hardware bound is because there may be a need to reuse the origin bindings for software bound keys. If this property is not set, it will default to `false`. Once set, it can no longer be updated. 57 | 58 | - `originBindings`: This is a list of strings which determines which origins have access to this cryptographic key for usage and management. Once an origin is set here, it can fully control the key in the same way as any other origin listed. If this property is not set, it will default to the origin of the caller. 59 | 60 | - `identifier`: The concept of an identifier here is to allow for the CryptoKey object to be referred to beyond the lifetime of the `CryptoKey` object returned by `generateKey`. This is especially useful when the key is being stored in an enclave or TPM where the key is not accessible to the application layer such that the key object can be handled by the application layer. One common pattern that I think should be expected is for an global identifier like a UUID or potentially a DID URL to be set here such that the key and cryptographic operations are performed by the browser, but the management, rotation, and usage are managed at a higher application layer such as a web wallet. 61 | 62 | - `updatable`: This allows the original creator to limit whether or not a key can be updated beyond the original values set. 63 | 64 | ### Update Key (grant a new origin access to to the key to use it) 65 | ```js 66 | await window.crypto.subtle.updateKey("123ABC", { 67 | originBindings: ["example.com", "acmecorp.com"], 68 | identifier: "3eac496b-1df8-4a4c-ac17-daf053d162d9" // changes from a local identifer specific to the origin to a global identifier 69 | }); 70 | ``` 71 | 72 | The design of this API is meant to build a permissions model around the origin such that the first origin must explicitly add the second origin. A user prompt is likely necessary in order to prevent cross site tracking via the identifier or keypair 73 | 74 | ### Use key to sign and verify a message 75 | ```js 76 | const ecdsaParams = { name: "ECDSA", hash: "SHA-256" }; 77 | const keyIdentifier = "3eac496b-1df8-4a4c-ac17-daf053d162d9"; 78 | const message = "Hello World!"; 79 | const signature = await window.crypto.subtle.sign(ecdsaParams, keyIdentifier, message); 80 | const verified = await window.crypto.subtle.verify(ecdsaParams, keyIdentifier, signature, message); 81 | 82 | if(verified) { 83 | console.log(message); 84 | } 85 | ``` 86 | 87 | In this API, any origin (such as `example.com` or `acmecorp.com`) with permission to access and use a key that's hardware backed can also opt to delete the key as well. If the key is shared across origins vai having permission granted, the `sign` call could be run by `example.com` and `verify` could be ran by `acmecorp.com` which could be useful for upgrading a bearer token to a Device Bound Session Credential all verified locally in a single page application. 88 | 89 | ### Delete key by identifier 90 | ```js 91 | await window.crypto.subtle.deleteKey("3eac496b-1df8-4a4c-ac17-daf053d162d9"); 92 | ``` 93 | 94 | In this API, any origin with permission to access and use a key that's hardware backed can also opt to delete the key as well. 95 | 96 | ### Managing keys used in higher level APIs 97 | Further, key management capabilities such as managing a key used for a browser API might look like this: 98 | 99 | ```js 100 | 101 | // Create a Passkey specifically for authentication purposes 102 | const passkey = await navigator.credentials.create({ 103 | publicKey: { 104 | challenge: new Uint8Array([1, 2, 3, 4]), // Example value 105 | rp: { 106 | name: "SimpleWebAuthn Example", 107 | id: "example.com" 108 | }, 109 | user: { 110 | id: "3eac496b-1df8-4a4c-ac17-daf053d162d9", // Example value 111 | name: "user@dev.com", 112 | displayName: "Passkey123", 113 | }, 114 | pubKeyCredParams: [ 115 | { alg: -7, type: "public-key" }, // ES256 116 | ], 117 | authenticatorSelection: { 118 | userVerification: "discouraged", 119 | }, 120 | }, 121 | }); 122 | 123 | // Reuse the key to sign data outside an authentication flow 124 | const ecdsaParams = const ecdsaParams = { name: "ECDSA", hash: "SHA-256" }; 125 | const message = "Hello World!"; 126 | const signature = await window.crypto.subtle.sign(ecdsaParams, passkey.rp.id, message); 127 | 128 | // limit access of a key created via a high level API to limit side effects. This would be done via `updatable` being set to `false` 129 | const expectedError = await window.crypto.subtle.updateKey("3eac496b-1df8-4a4c-ac17-daf053d162d9", { 130 | originBindings: ["example.com", "acmecorp.com"], 131 | }); 132 | 133 | console.log(expectedError) // returns an error like "cannot update this key". 134 | 135 | // delete the passkey 136 | await window.crypto.subtle.deleteKey("3eac496b-1df8-4a4c-ac17-daf053d162d9"); 137 | 138 | ``` 139 | 140 | In this case, we've created a browser backed passkey via the passkey registration API (the user would select browser profile in the consent flow) and then can re-use the key for additional flows. In this case, because the key is not updatable it can only be used within the origin that called the registration. This is done to limit side effects of the key being reused across origins and to limit the effects of key re-use across different signature flows. 141 | 142 | ## Detailed design discussion 143 | 144 | ### Permissions model currently grants unilateral authority across origins 145 | 146 | In order to reduce the complexity of the permissions model at this layer, this design opted to grant all permissions based on the origin. It's theoretically possible for this API to have a more complex API in order to handle more fine-grained permissions. For example, the origin that generates the key could set a more complex model where instead of the `originBinding` property containing just an array of origins, it would instead be an array of objects that define a more fine grained access control model. 147 | 148 | ### Cross origin tracking needs mitigation 149 | 150 | While a user permission would be the easy answer for preventing cross origin tracking based on a public key or key identifier, this doesn't seem like an ideal solution and further considerations is needed here. Handling this in a cross origin context means that it keeps this functionality very low level and likely requires user prompting and user consent. However, it's not clear that the permissions context to this will be understood since it won't always be clear what the key is used for. 151 | 152 | The reason, this is necessary though is because in certain use cases such as the cryptocurrency wallet example, locking a key to a particular origin (in this case an extension origin) would limit the ability for the user to move between wallets without incurring fees to transfer assets between one account to another. In most, cases the answer would likely be to re-issue a credential or token such that a key remains isolated to an origin. This may also be possible in the case of cryptocurrency wallets, but would require changes to blockchain account logic. 153 | 154 | ### Should Extension be allowed to call this API on an origin? 155 | 156 | If the API is meant to be origin isolated then we may need to limit extensions ability to call this. Otherwise malicious content scripts can be used to execute and bypass the permissions model here. Traditionally, this has not fit within the browser security model because installed extensions are considered trusted. However, this may be a time to consider adjusting this security model. 157 | 158 | ## Considered alternatives 159 | 160 | One consideration that was [raised](https://github.com/w3c/webcrypto/issues/263#issuecomment-1743145628) by [@RByers](https://github.com/RByers) was to focus this more within higher level API designs. This would enable further hardware backed keys within browser APIs themselves. However, it likely wouldn't address many of the application level use cases which likely won't ever be addressed as web platform specific APIs. Hence, having an outlet via a low level extension in Web Crypto that can be built upon seemed more reasonable. 161 | 162 | ## Stakeholder Feedback / Opposition 163 | 164 | At this time, this explainer has not been shared around enough to garner feedback from various stakeholders such as implementers or other browser vendors. Further consideration is needed and this section will be updated accordingly when it's more clear how other participants think about this. 165 | 166 | ## References & acknowledgements 167 | 168 | Here's a non-exhaustive list of people who should be ackowledged for their discussion so far: 169 | 170 | - WebCrypto API WG who first considered this and ultimately opted to not include this in the first version, but made note of their discussions in the spec. 171 | - Anonymous Author for their writeup in [this issue](https://github.com/w3c/webcrypto/issues/263) 172 | - Further participant feedback during the discussion on the issue linked above 173 | --------------------------------------------------------------------------------