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README.md

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··· 51 51 and `aud` when they are present even if you did not configure matching claims: 52 52 expired tokens are rejected, not-yet-valid tokens are rejected, and tokens with 53 53 an `aud` claim are rejected unless you explicitly accept that audience. Audience 54 54 - validation currently expects string values. 54 54 + validation accepts string and array values. 55 55 56 56 JWTs have no built-in revocation. If you need logout, account disablement, or 57 57 emergency key compromise handling, keep server-side state such as short token

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TODO.md

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··· 6 6 7 7 - [x] Introduce separate error for HeaderDecodeFailed similar to Payload 8 8 - [x] Replace typ HeaderDecodeError with custom error variant. 9 9 - - Make claims a non-empty list 9 9 + - [x] Support array-valued `aud` claims 10 10 + - [x] Use a dedicated default `aud` validator that rejects any present audience 11 11 + unless the caller explicitly accepts it 12 12 + - [x] Accept fractional `NumericDate` values for spec compatibility 10 13 - Come up with a custom decode api to be able to error on onknown data fields

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core/src/ywt/claim.gleam

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··· 21 21 import gleam/dynamic 22 22 import gleam/dynamic/decode.{type Decoder, type Dynamic} 23 23 import gleam/float 24 24 + import gleam/int 24 25 import gleam/json.{type Json} 25 26 import gleam/list 26 27 import gleam/option.{None, Some} 27 28 import gleam/order 29 29 + import gleam/string 28 30 import gleam/time/duration.{type Duration} 29 31 import gleam/time/timestamp.{type Timestamp} 30 32 import ywt/internal/core.{type ParseError} ··· 117 119 /// The `aud` claim identifies who the token is meant for. 118 120 /// 119 121 /// Tokens with an `aud` field are rejected by default unless you add this claim 120 120 - /// and the value matches one of the accepted audiences. ywt currently validates 121 121 - /// string audiences; array-valued `aud` fields are rejected. 122 122 + /// and the value matches one of the accepted audiences. ywt validates both 123 123 + /// string and array-valued `aud` fields. 122 124 /// 123 125 /// ```gleam 124 126 /// let claims = [ ··· 128 130 /// ] 129 131 /// ``` 130 132 pub fn audience(primary: String, others: List(String)) -> Claim { 131 131 - string_claim("aud", primary, others, core.InvalidAudience) 133 133 + let name = "aud" 134 134 + let expected = [primary, ..others] 135 135 + let value = fn() { json.string(primary) } 136 136 + 137 137 + let verify = 138 138 + validate( 139 139 + name, 140 140 + audience_decoder(), 141 141 + invalid_audience(expected, _), 142 142 + any_audience_matches(_, expected), 143 143 + ) 144 144 + 145 145 + PayloadClaim(name:, is_required: True, value:, verify:) 132 146 } 133 147 134 148 /// The `nbf` claim says the token must not be accepted before a time. ··· 294 308 PayloadClaim(name:, is_required: True, value:, verify:) 295 309 } 296 310 311 311 + fn audience_decoder() -> Decoder(List(String)) { 312 312 + decode.one_of(decode.map(decode.string, list.wrap), or: [ 313 313 + decode.list(decode.string), 314 314 + ]) 315 315 + } 316 316 + 317 317 + fn any_audience_matches(found: List(String), expected: List(String)) -> Bool { 318 318 + use audience <- list.any(found) 319 319 + list.contains(expected, audience) 320 320 + } 321 321 + 322 322 + fn invalid_audience(expected: List(String), found: List(String)) -> ParseError { 323 323 + let actual = case found { 324 324 + [] -> "[]" 325 325 + [_, ..] -> string.join(found, with: ", ") 326 326 + } 327 327 + 328 328 + core.InvalidAudience(expected, actual) 329 329 + } 330 330 + 331 331 + fn timestamp_from_numeric_date_float(seconds: Float) -> Timestamp { 332 332 + let whole_seconds = seconds |> float.floor |> float.truncate 333 333 + let fractional_seconds = seconds -. int.to_float(whole_seconds) 334 334 + let nanoseconds = float.round(fractional_seconds *. 1_000_000_000.0) 335 335 + 336 336 + timestamp.from_unix_seconds_and_nanoseconds( 337 337 + seconds: whole_seconds, 338 338 + nanoseconds: nanoseconds, 339 339 + ) 340 340 + } 341 341 + 297 342 /// Decodes a JWT numeric date into a timestamp. 298 343 /// 299 299 - /// JWT numeric dates are integer seconds since the Unix epoch. 344 344 + /// JWT numeric dates are seconds since the Unix epoch. 300 345 /// 301 346 /// ```gleam 302 347 /// decode.field("exp", claim.numeric_date_decoder()) 303 348 /// ``` 304 349 pub fn numeric_date_decoder() -> Decoder(Timestamp) { 305 305 - decode.map(decode.int, timestamp.from_unix_seconds) 350 350 + decode.one_of(decode.map(decode.int, timestamp.from_unix_seconds), or: [ 351 351 + decode.map(decode.float, timestamp_from_numeric_date_float), 352 352 + ]) 306 353 } 307 354 308 355 /// Encodes a timestamp as a JWT numeric date. 309 356 /// 310 310 - /// Fractional seconds are truncated because JWT numeric dates use integer Unix 311 311 - /// seconds. 357 357 + /// Fractional seconds are truncated to keep encoded JWTs compact. 312 358 /// 313 359 /// ```gleam 314 360 /// #("checked_at", claim.encode_numeric_date(timestamp.system_time())) ··· 354 400 /// 355 401 /// Tokens with `exp` and `nbf` are checked by default with zero leeway. Tokens 356 402 /// with `aud` are rejected by default unless you pass an `audience` claim. 357 357 - /// Audience validation expects a string value. 403 403 + /// Audience validation accepts string or array values. 358 404 pub fn verify( 359 405 payload: Dynamic, 360 406 claims: List(Claim), ··· 366 412 /// 367 413 /// This is a low-level helper used by ywt. It adds default checks for `exp`, 368 414 /// `nbf`, and `aud` when you have not configured those claims yourself. 369 369 - /// Audience validation expects a string value. 415 415 + /// Audience validation accepts string or array values. 370 416 @internal 371 417 pub fn verify_with_header( 372 418 header: Dynamic, ··· 376 422 claims 377 423 |> add_default_claim(expires_at(duration.seconds(0), duration.seconds(0))) 378 424 |> add_default_claim(not_before(timestamp.system_time(), duration.seconds(0))) 379 379 - |> add_default_claim(audience("", [])) 425 425 + |> add_default_claim(reject_present_audience()) 380 426 |> list.try_each(verify_single_claim(header, payload, _)) 427 427 + } 428 428 + 429 429 + fn reject_present_audience() -> Claim { 430 430 + let name = "aud" 431 431 + let value = fn() { json.string("") } 432 432 + 433 433 + let verify = 434 434 + validate(name, audience_decoder(), invalid_audience([], _), fn(_) { False }) 435 435 + 436 436 + PayloadClaim(name:, is_required: False, value:, verify:) 381 437 } 382 438 383 439 fn add_default_claim(claims, claim: Claim) {

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erlang/README.md

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··· 50 50 and `aud` when they are present even if you did not configure matching claims: 51 51 expired tokens are rejected, not-yet-valid tokens are rejected, and tokens with 52 52 an `aud` claim are rejected unless you explicitly accept that audience. Audience 53 53 - validation currently expects string values. 53 53 + validation accepts string and array values. 54 54 55 55 JWTs have no built-in revocation. If you need logout, account disablement, or 56 56 emergency key compromise handling, keep server-side state such as short token

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erlang/src/ywt.gleam

Reviewed

··· 220 220 /// 221 221 /// Tokens with `exp` and `nbf` are checked by default with zero leeway. Tokens 222 222 /// with `aud` are rejected by default unless you pass an `audience` claim. 223 223 - /// Audience validation expects a string value. 223 223 + /// Audience validation accepts string or array values. 224 224 /// 225 225 /// Unknown JWT header fields are ignored by ywt. Unknown payload fields are 226 226 /// accepted or rejected by your payload decoder.

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test/tests.gleam

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··· 49 49 } 50 50 } 51 51 52 52 + fn signed_jwt(payload: json.Json, key: SignKey) { 53 53 + let verify_key = verify_key.derived(key) 54 54 + let assert Ok(alg) = verify_key.algorithm(verify_key) 55 55 + 56 56 + let header = 57 57 + json.object([ 58 58 + #("alg", algorithm.to_json(alg)), 59 59 + ]) 60 60 + 61 61 + let header = 62 62 + bit_array.base64_url_encode(<<json.to_string(header):utf8>>, False) 63 63 + let payload = 64 64 + bit_array.base64_url_encode(<<json.to_string(payload):utf8>>, False) 65 65 + let message = header <> "." <> payload 66 66 + 67 67 + use signature <- await(sign_bits(<<message:utf8>>, key)) 68 68 + 69 69 + resolve(message <> "." <> bit_array.base64_url_encode(signature, False)) 70 70 + } 71 71 + 52 72 // ================================================================================================ 53 73 // KEY GENERATION AND LOADING HELPERS 54 74 // ================================================================================================ ··· 442 462 parse(jwt_with_audience, decode.dynamic, wrong_audience_claims, [verify_key]), 443 463 ) 444 464 let assert Error(InvalidAudience(_, _)) = result 465 465 + 466 466 + resolve(Nil) 467 467 + } 468 468 + 469 469 + pub fn audience_array_validation_test() { 470 470 + use sign_key <- loop(sign_keys()) 471 471 + let verify_key = verify_key.derived(sign_key) 472 472 + 473 473 + let payload = 474 474 + json.object([ 475 475 + #("sub", json.string("user123")), 476 476 + #("exp", json.int(9_876_543_210)), 477 477 + #( 478 478 + "aud", 479 479 + json.array( 480 480 + ["https://other.example.com", "https://api.example.com"], 481 481 + json.string, 482 482 + ), 483 483 + ), 484 484 + ]) 485 485 + use jwt_with_audience <- await(signed_jwt(payload, sign_key)) 486 486 + 487 487 + let claims = [ 488 488 + expires_at(duration.hours(1), duration.minutes(5)), 489 489 + audience("https://api.example.com", []), 490 490 + ] 491 491 + use result <- await( 492 492 + parse(jwt_with_audience, decode.dynamic, claims, [ 493 493 + verify_key, 494 494 + ]), 495 495 + ) 496 496 + let assert Ok(_) = result 497 497 + 498 498 + let wrong_claims = [ 499 499 + expires_at(duration.hours(1), duration.minutes(5)), 500 500 + audience("https://different-api.com", []), 501 501 + ] 502 502 + use result <- await( 503 503 + parse(jwt_with_audience, decode.dynamic, wrong_claims, [ 504 504 + verify_key, 505 505 + ]), 506 506 + ) 507 507 + let assert Error(InvalidAudience( 508 508 + _, 509 509 + "https://other.example.com, https://api.example.com", 510 510 + )) = result 445 511 446 512 resolve(Nil) 447 513 } ··· 1084 1150 parse(jwt_with_aud, decode.dynamic, parse_claims, [verify_key]), 1085 1151 ) 1086 1152 let assert Error(InvalidAudience(_, _)) = result 1153 1153 + 1154 1154 + resolve(Nil) 1155 1155 + } 1156 1156 + 1157 1157 + pub fn rejects_array_audience_token_without_explicit_aud_claim_test() { 1158 1158 + use sign_key <- loop(sign_keys()) 1159 1159 + let verify_key = verify_key.derived(sign_key) 1160 1160 + 1161 1161 + let payload = 1162 1162 + json.object([ 1163 1163 + #("sub", json.string("user123")), 1164 1164 + #("exp", json.int(9_876_543_210)), 1165 1165 + #( 1166 1166 + "aud", 1167 1167 + json.array( 1168 1168 + ["https://api.example.com", "https://other.example.com"], 1169 1169 + json.string, 1170 1170 + ), 1171 1171 + ), 1172 1172 + ]) 1173 1173 + use jwt_with_aud <- await(signed_jwt(payload, sign_key)) 1174 1174 + 1175 1175 + use result <- await(parse(jwt_with_aud, decode.dynamic, [], [verify_key])) 1176 1176 + let assert Error(InvalidAudience(_, _)) = result 1177 1177 + 1178 1178 + resolve(Nil) 1179 1179 + } 1180 1180 + 1181 1181 + pub fn accepts_fractional_numeric_date_claims_test() { 1182 1182 + use sign_key <- loop(sign_keys()) 1183 1183 + let verify_key = verify_key.derived(sign_key) 1184 1184 + 1185 1185 + let now = timestamp.to_unix_seconds(timestamp.system_time()) 1186 1186 + let payload = 1187 1187 + json.object([ 1188 1188 + #("sub", json.string("user123")), 1189 1189 + #("exp", json.float(now +. 3600.5)), 1190 1190 + #("nbf", json.float(now -. 1.5)), 1191 1191 + ]) 1192 1192 + use jwt <- await(signed_jwt(payload, sign_key)) 1193 1193 + 1194 1194 + use result <- await(parse(jwt, decode.dynamic, [], [verify_key])) 1195 1195 + let assert Ok(_) = result 1196 1196 + 1197 1197 + resolve(Nil) 1198 1198 + } 1199 1199 + 1200 1200 + pub fn rejects_expired_fractional_numeric_date_claim_test() { 1201 1201 + use sign_key <- loop(sign_keys()) 1202 1202 + let verify_key = verify_key.derived(sign_key) 1203 1203 + 1204 1204 + let payload = 1205 1205 + json.object([ 1206 1206 + #("sub", json.string("user123")), 1207 1207 + #( 1208 1208 + "exp", 1209 1209 + json.float(timestamp.to_unix_seconds(timestamp.system_time()) -. 3600.5), 1210 1210 + ), 1211 1211 + ]) 1212 1212 + use jwt <- await(signed_jwt(payload, sign_key)) 1213 1213 + 1214 1214 + use result <- await(parse(jwt, decode.dynamic, [], [verify_key])) 1215 1215 + let assert Error(TokenExpired(_)) = result 1087 1216 1088 1217 resolve(Nil) 1089 1218 }

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webcrypto/README.md

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··· 50 50 and `aud` when they are present even if you did not configure matching claims: 51 51 expired tokens are rejected, not-yet-valid tokens are rejected, and tokens with 52 52 an `aud` claim are rejected unless you explicitly accept that audience. Audience 53 53 - validation currently expects string values. 53 53 + validation accepts string and array values. 54 54 55 55 JWTs have no built-in revocation. If you need logout, account disablement, or 56 56 emergency key compromise handling, keep server-side state such as short token

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webcrypto/src/ywt.gleam

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··· 222 222 /// 223 223 /// Tokens with `exp` and `nbf` are checked by default with zero leeway. Tokens 224 224 /// with `aud` are rejected by default unless you pass an `audience` claim. 225 225 - /// Audience validation expects a string value. 225 225 + /// Audience validation accepts string or array values. 226 226 /// 227 227 /// Unknown JWT header fields are ignored by ywt. Unknown payload fields are 228 228 /// accepted or rejected by your payload decoder.