Fix cross-platform strong name signing by manually parsing RSA key blobs

Author: Ahmed

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
 
@@ -126,9 +126,11 @@ type BlobReader =
     val mutable _blob: byte array
     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.Offset
+        with get () = x._offset
+        and set (v) = x._offset <- v
+
     member x.ReadInt32() : int =
         let offset = x._offset
         x._offset <- offset + 4
@@ -147,14 +149,13 @@ type BlobReader =
 let RSAParametersFromBlob blob keyType =
     let mutable reader = BlobReader blob
 
-    let header = reader.ReadInt32()
-    if header <> 0x00000206 && header <> 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()
@@ -163,15 +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) =
@@ -304,26 +310,43 @@ let signStream stream keyBlob =
     patchSignature stream peReader signature
 
 let signatureSize (pk: byte array) =
-    if pk.Length < 20 then 0
+    if pk.Length < 20 then
+        0
     else
         let reader = BlobReader pk
-        reader.Offset <- 12
-        let bitLen = reader.ReadInt32()
-        let modulusLength = bitLen / 8
-        
-        if modulusLength < 160 then 128 else modulusLength - 32
-// Key signing
-type keyContainerName = string
-type keyPair = byte array
-type pubkey = byte array
-type pubkeyOptions = byte array * bool
 
+        let findRsaSize () =
+            [ 8; 20; 32 ]
+            |> List.tryPick (fun offset ->
+                if pk.Length >= offset + 8 then
+                    reader.Offset <- offset
+                    let magic = reader.ReadInt32()
+
+                    if magic = RSA_PUB_MAGIC || magic = RSA_PRIV_MAGIC then
+                        let bitLen = reader.ReadInt32()
+                        Some(bitLen / 8)
+                    else
+                        None
+                else
+                    None)
+
+        match findRsaSize () with
+        | Some size -> if size < 128 then 128 else size
+        | None -> if pk.Length < 160 then 128 else pk.Length - 32
+
+// Returns a CLR Format Blob public key
 let getPublicKeyForKeyPair keyBlob =
     use rsa = RSA.Create()
     rsa.ImportParameters(RSAParametersFromBlob keyBlob KeyType.KeyPair)
     let rsaParameters = rsa.ExportParameters false
     toCLRKeyBlob rsaParameters CALG_RSA_KEYX
 
+// Key signing
+type keyContainerName = string
+type keyPair = byte array
+type pubkey = byte array
+type pubkeyOptions = byte array * bool
+
 let signerGetPublicKeyForKeyPair (kp: keyPair) : pubkey = getPublicKeyForKeyPair kp
 
 let signerSignatureSize (pk: pubkey) : int = signatureSize pk
@@ -367,8 +390,7 @@ type ILStrongNameSigner =
         | KeyContainer _ -> failWithContainerSigningUnsupportedOnThisPlatform ()
 
     member s.SignatureSize =
-        let pkSignatureSize pk =
-            signerSignatureSize pk
+        let pkSignatureSize pk = signerSignatureSize pk
 
         match s with
         | PublicKeySigner pk -> pkSignatureSize pk