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FunctionNameExtractor locates the signature and n-transform functions within a downloaded YouTube player_ias.vflset JS file. It checks PlayerConfigStore first — using validated, CDN-proven configs — and falls back to heuristic regex patterns only when no config entry is found for the player hash. Package: com.zemer.cipher
Hardcoded configs always take precedence over regex extraction. A false positive from a legacy heuristic pattern cannot shadow a validated config entry. This also means a failed regex match on a known player hash is never a problem — the config path handles it.

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Data Classes

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SigFunctionInfo

Carries everything the cipher WebView needs to call the signature deobfuscation function. 
data class SigFunctionInfo(
    val name: String,
    val constantArg: Int?,
    val constantArgs: List<Int>? = null,
    val preprocessFunc: String? = null,
    val preprocessArgs: List<Int>? = null,
    val isHardcoded: Boolean = false,
    val jsExpression: String? = null
)
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name
String
The extracted or sentinel function name. When jsExpression is non-null this is a sentinel value ("_expr_sig") and is not used for JS calls — jsExpression is used instead.
​
constantArg
Int?
A single integer constant argument passed as the first parameter to the sig function. Populated by legacy regex extraction. null for expression-based configs and when not applicable.
​
constantArgs
List<Int>?
Multiple integer constant arguments passed to the sig function. Used for patterns that require more than one constant.
​
preprocessFunc
String?
Name of a preprocessing function to call on the signature before passing it to the main sig function. null when not required.
​
preprocessArgs
List<Int>?
Integer constant arguments for preprocessFunc. null when preprocessFunc is null.
​
isHardcoded
Boolean
true when this info came from a PlayerConfigStore entry rather than from regex extraction. CipherWebView uses this flag to choose the correct export injection strategy.
​
jsExpression
String?
Full JS expression for VM-dispatch players where no named function can be extracted. The placeholder INPUT is replaced with the obfuscated signature at export time. When non-null, this is used instead of name / constantArg.

​
NFunctionInfo

Carries everything the cipher WebView needs to call the n-transform function. 
data class NFunctionInfo(
    val name: String,
    val arrayIndex: Int?,
    val constantArgs: List<Int>? = null,
    val isHardcoded: Boolean = false,
    val jsExpression: String? = null
)
​
name
String
The extracted or sentinel function name. When jsExpression is non-null this is a sentinel value ("_expr_n") and is not used for JS calls.
​
arrayIndex
Int?
Array index used when the n-transform function is stored in an array rather than as a top-level binding. null when the function is accessed directly by name.
​
constantArgs
List<Int>?
Integer constant arguments prepended when calling the n-transform function. Populated when the function requires additional parameters beyond the n-value itself.
​
isHardcoded
Boolean
true when this info came from a PlayerConfigStore entry rather than from regex extraction.
​
jsExpression
String?
Full JS expression for the n-transform. INPUT is replaced with the n-value at export time. When non-null, this is used instead of name / arrayIndex.

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HardcodedPlayerConfig

The in-memory representation of a single validated player config entry. Instances are created by PlayerConfigParser and stored in PlayerConfigStore. 
data class HardcodedPlayerConfig(
    val sigFuncName: String,
    val sigConstantArg: Int?,
    val sigConstantArgs: List<Int>? = null,
    val sigPreprocessFunc: String? = null,
    val sigPreprocessArgs: List<Int>? = null,
    val sigJsExpression: String?,
    val nFuncName: String,
    val nArrayIndex: Int?,
    val nConstantArgs: List<Int>?,
    val nJsExpression: String?,
    val signatureTimestamp: Int
)
​
sigFuncName
String
Sentinel sig function name. Set to "_expr_sig" for all config-file-sourced entries.
​
sigConstantArg
Int?
Single integer constant argument for the sig function. null for expression-based configs.
​
sigConstantArgs
List<Int>?
Multiple integer constant arguments for the sig function. null for expression-based configs.
​
sigPreprocessFunc
String?
Name of a preprocessing function applied to the signature before the main sig call. null for config-file-sourced entries.
​
sigPreprocessArgs
List<Int>?
Arguments for sigPreprocessFunc. null when sigPreprocessFunc is null.
​
sigJsExpression
String?
The sig call expression from the config file (e.g. "mP(4,155,INPUT)"). INPUT is replaced with the obfuscated signature at export time.
​
nFuncName
String
Sentinel n-function name. Set to "_expr_n" for all config-file-sourced entries.
​
nArrayIndex
Int?
Array index for the n-transform function. null for config-file-sourced entries (the IIFE handles indexing internally).
​
nConstantArgs
List<Int>?
Integer constant arguments for the n-transform function. null for config-file-sourced entries.
​
nJsExpression
String?
The n-transform IIFE built by PlayerConfigParser.buildNJsExpression. INPUT is replaced with the n-value at export time.
​
signatureTimestamp
Int
The signatureTimestamp (sts) value for this player. Sent in InnerTube /player API requests.

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Functions

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hasQArrayObfuscation

fun hasQArrayObfuscation(playerJs: String): Boolean
Checks whether the player JS uses the Q-array obfuscation pattern — a var Q = "...".split("}") construct. analyzePlayerJs records this as the hasQArrayObfuscation field in the returned PlayerAnalysis.
​
playerJs
String
required
The full text of the YouTube player_ias.vflset JavaScript file.
Returns: true if the Q-array pattern is detected, false otherwise.

​
extractSigFunctionInfo

fun extractSigFunctionInfo(playerJs: String, knownHash: String? = null): SigFunctionInfo?
Extracts signature function information from player JS. Config lookup is tried first; if no config is found for the resolved hash, legacy unanchored regex patterns are tried in order. Returns null if both paths fail.
​
playerJs
String
required
The full text of the YouTube player_ias.vflset JavaScript file.
​
knownHash
String?
An already-known 8-hex player hash (e.g. from PlayerJsFetcher). When provided, the hash extraction step is skipped. When null, extractPlayerHash is called first.

​
extractNFunctionInfo

fun extractNFunctionInfo(playerJs: String, knownHash: String? = null): NFunctionInfo?
Extracts n-transform function information from player JS. Same config-first precedence as extractSigFunctionInfo. Returns null if both paths fail.
​
playerJs
String
required
The full text of the YouTube player_ias.vflset JavaScript file.
​
knownHash
String?
An already-known 8-hex player hash. When null, extractPlayerHash is called first.

​
extractSignatureTimestamp

fun extractSignatureTimestamp(playerJs: String, knownHash: String? = null): Int?
Extracts the signatureTimestamp (sts) value. Three sources are tried in priority order:
  1. Anchored signatureTimestamp literal in the JS (e.g. signatureTimestamp:20613) — the player’s own embedded field, immune to config typos or stale remote pushes.
  2. Config sts value — used when the JS literal is absent, for players that don’t embed the field directly.
  3. Loose sts pattern — a last-resort unanchored search that can false-match anywhere in ~2 MB of JS; only used when the other two paths both fail.
Returns null if all three sources fail.
​
playerJs
String
required
The full text of the YouTube player_ias.vflset JavaScript file.
​
knownHash
String?
An already-known 8-hex player hash used to look up the config sts. When null, extractPlayerHash is called if needed.

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analyzePlayerJs

fun analyzePlayerJs(playerJs: String, knownHash: String? = null): PlayerAnalysis
Runs a full analysis of the player JS in a single call, returning a PlayerAnalysis that bundles all extracted values. Internally calls extractPlayerHash, hasQArrayObfuscation, extractSigFunctionInfo, extractNFunctionInfo, and extractSignatureTimestamp.
​
playerJs
String
required
The full text of the YouTube player_ias.vflset JavaScript file.
​
knownHash
String?
An already-known 8-hex player hash. When provided, hash extraction is skipped and this value is used for all config lookups.
Returns: PlayerAnalysis(playerHash, hasQArrayObfuscation, sigInfo, nFuncInfo, signatureTimestamp)

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extractPlayerHash

fun extractPlayerHash(playerJs: String): String?
Extracts the 8-hex player hash from the JS content using a list of URL patterns (looking for /player/<hash>/ in jsUrl, player_ias.vflset, and /s/player/ patterns). If all URL patterns fail, falls back to computing the MD5 of the first 10 000 characters of the JS and returning the first 4 bytes as an 8-hex string. This MD5-based hash is registered as an alias in config entries.
​
playerJs
String
required
The full text of the YouTube player_ias.vflset JavaScript file.

​
getHardcodedConfig

fun getHardcodedConfig(playerHash: String): HardcodedPlayerConfig?
Looks up the player hash in PlayerConfigStore. Returns the HardcodedPlayerConfig if found, or null if the hash (and none of its aliases) is in the current table.
​
playerHash
String
required
The 8-hex player hash to look up. Both primary hashes and alias hashes are accepted.

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