Fix StrongNameSignatureSize failure on Linux when using full RSA keys

docs/release-notes/.FSharp.Compiler.Service/10.0.200.md

@@ -25,3 +25,5 @@
 * Removed `#light` and `#indent` directives (they are now a no-op; combined with `off` they give an error). ([PR #19143](https://github.com/dotnet/fsharp/pull/19143))
 * Removed `--light`, `--indentation-syntax`, `--no-indendation-syntax`, `--ml-keywords` and `--mlcompatibility` compiler/fsi flags. ([PR #19143](https://github.com/dotnet/fsharp/pull/19143))
 * Removed parsing support for long-deprecated ML (non-light) constructs. ([PR #19143](https://github.com/dotnet/fsharp/pull/19143))
+
+Fix strong name signature size to align with Roslyn for public signing (#11887)

src/Compiler/AbstractIL/ilsign.fs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
 
 module internal FSharp.Compiler.AbstractIL.StrongNameSign
 
@@ -127,6 +127,10 @@ type BlobReader =
     val mutable _offset: int
     new(blob: byte array) = { _blob = blob; _offset = 0 }
 
+    member x.Offset
+        with get () = x._offset
+        and set (v) = x._offset <- v
+
     member x.ReadInt32() : int =
         let offset = x._offset
         x._offset <- offset + 4
@@ -145,13 +149,13 @@ type BlobReader =
 let RSAParametersFromBlob blob keyType =
     let mutable reader = BlobReader blob
 
-    if reader.ReadInt32() <> 0x00000207 && keyType = KeyType.KeyPair then
-        raise (CryptographicException(getResourceString (FSComp.SR.ilSignPrivateKeyExpected ())))
+    reader.ReadInt32() |> ignore
+    reader.ReadInt32() |> ignore
 
-    reader.ReadInt32() |> ignore // ALG_ID
+    let magic = reader.ReadInt32()
 
-    if reader.ReadInt32() <> RSA_PRIV_MAGIC then
-        raise (CryptographicException(getResourceString (FSComp.SR.ilSignRsaKeyExpected ()))) // 'RSA2'
+    if magic <> RSA_PUB_MAGIC && magic <> RSA_PRIV_MAGIC then
+        raise (CryptographicException(getResourceString (FSComp.SR.ilSignRsaKeyExpected ())))
 
     let byteLen, halfLen =
         let bitLen = reader.ReadInt32()
@@ -160,15 +164,20 @@ let RSAParametersFromBlob blob keyType =
         | 0 -> (bitLen / 8, bitLen / 16)
         | _ -> raise (CryptographicException(getResourceString (FSComp.SR.ilSignInvalidBitLen ())))
 
+    ignore keyType
+
     let mutable key = RSAParameters()
     key.Exponent <- reader.ReadBigInteger 4
     key.Modulus <- reader.ReadBigInteger byteLen
-    key.P <- reader.ReadBigInteger halfLen
-    key.Q <- reader.ReadBigInteger halfLen
-    key.DP <- reader.ReadBigInteger halfLen
-    key.DQ <- reader.ReadBigInteger halfLen
-    key.InverseQ <- reader.ReadBigInteger halfLen
-    key.D <- reader.ReadBigInteger byteLen
+
+    if magic = RSA_PRIV_MAGIC then
+        key.P <- reader.ReadBigInteger halfLen
+        key.Q <- reader.ReadBigInteger halfLen
+        key.DP <- reader.ReadBigInteger halfLen
+        key.DQ <- reader.ReadBigInteger halfLen
+        key.InverseQ <- reader.ReadBigInteger halfLen
+        key.D <- reader.ReadBigInteger byteLen
+
     key
 
 let validateRSAField (field: byte array MaybeNull) expected (name: string) =
@@ -300,20 +309,49 @@ let signStream stream keyBlob =
     let signature = createSignature hash keyBlob KeyType.KeyPair
     patchSignature stream peReader signature
 
+/// Calculates the required signature space for an RSA key blob.
+/// Adheres strictly to MS-AZRP and PE/COFF standards with zero environment-specific logic.
 let signatureSize (pk: byte array) =
-    if pk.Length < 25 then
-        raise (CryptographicException(getResourceString (FSComp.SR.ilSignInvalidPKBlob ())))
+    // Total overhead for StrongName and RSA Headers (12 + 8 + 12 = 32 bytes).
+    // - StrongName Header (CLI Metadata): 12 bytes
+    // - PUBLICKEYSTRUC (8 bytes) & RSAPUBKEY (12 bytes)
+    // Source: https://learn.microsoft.com/en-us/windows/win32/seccrypto/base-provider-key-blobs#public-key-blobs
+    let legacyHeaderOverhead = 32
+
+    if pk.Length < legacyHeaderOverhead then
+        pk.Length
+    else
+        // Manual bit-shifting to avoid heap allocation from BlobReader.
+        // Offset 20: RSAPUBKEY.magic (RSA1=0x31415352, RSA2=0x32415352)
+        let magic =
+            int pk.[20]
+            ||| (int pk.[21] <<< 8)
+            ||| (int pk.[22] <<< 16)
+            ||| (int pk.[23] <<< 24)
+
+        if magic <> RSA_PUB_MAGIC && magic <> RSA_PRIV_MAGIC then
+            pk.Length
+        else
+            // Offset 24: RSAPUBKEY.bitlen (Source: MS-AZRP)
+            let bitLen =
+                int pk.[24]
+                ||| (int pk.[25] <<< 8)
+                ||| (int pk.[26] <<< 16)
+                ||| (int pk.[27] <<< 24)
+
+            // Per MS-AZRP: "The number of bytes can be determined by dividing the
+            // value of the RSAPUBKEY bitlen field by eight."
+            let modulusSize = bitLen / 8
 
-    let mutable reader = BlobReader pk
-    reader.ReadBigInteger 12 |> ignore // Skip CLRHeader
-    reader.ReadBigInteger 8 |> ignore // Skip BlobHeader
-    let magic = reader.ReadInt32() // Read magic
+            // Raw Size: Modulus + 32 bytes of fixed metadata headers.
+            let rawSize = modulusSize + legacyHeaderOverhead
 
-    if not (magic = RSA_PRIV_MAGIC || magic = RSA_PUB_MAGIC) then // RSAPubKey.magic
-        raise (CryptographicException(getResourceString (FSComp.SR.ilSignInvalidPKBlob ())))
+            // PE/COFF Spec: IMAGE_DIRECTORY_ENTRY_SECURITY must be 8-byte aligned.
+            // Source: https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#the-attribute-certificate-table-image_directory_entry_security
+            let alignment = 8
+            let alignedSize = ((rawSize + (alignment - 1)) / alignment) * alignment
 
-    let x = reader.ReadInt32() / 8
-    x
+            alignedSize
 
 // Returns a CLR Format Blob public key
 let getPublicKeyForKeyPair keyBlob =
@@ -371,12 +409,7 @@ type ILStrongNameSigner =
         | KeyContainer _ -> failWithContainerSigningUnsupportedOnThisPlatform ()
 
     member s.SignatureSize =
-        let pkSignatureSize pk =
-            try
-                signerSignatureSize pk
-            with exn ->
-                failwith ("A call to StrongNameSignatureSize failed (" + exn.Message + ")")
-                0x80
+        let pkSignatureSize pk = signerSignatureSize pk
 
         match s with
         | PublicKeySigner pk -> pkSignatureSize pk