Merge pull request #1029 from WFrost3/RSA-PublicKeyDER-Support-Any-Size

Update RSA's publicKeyDER method to support exponent any byte length
krzyzanowskim · Dec 6, 2023 · 3e56b61 · 3e56b61
2 parents 23bc51a + 9a6b676
commit 3e56b61
Show file tree

Hide file tree

Showing 2 changed files with 64 additions and 1 deletion.
diff --git a/Sources/CryptoSwift/RSA/RSA.swift b/Sources/CryptoSwift/RSA/RSA.swift
@@ -283,10 +283,11 @@ extension RSA {
   /// ```
   func publicKeyDER() throws -> Array<UInt8> {
     let mod = self.n.serialize()
+    let exp = self.e.serialize()
     let pubKeyAsnNode: ASN1.Node =
       .sequence(nodes: [
         .integer(data: DER.i2ospData(x: mod.bytes, size: self.keySizeBytes)),
-        .integer(data: DER.i2ospData(x: self.e.serialize().bytes, size: 3))
+        .integer(data: DER.i2ospData(x: exp.bytes, size: exp.bytes.count))
       ])
     return ASN1.Encoder.encode(pubKeyAsnNode)
   }

diff --git a/Tests/CryptoSwiftTests/RSASecKeyTests.swift b/Tests/CryptoSwiftTests/RSASecKeyTests.swift
@@ -61,7 +61,69 @@
       XCTAssertEqual(rsaSecKeyRawRep, Data(rsaCryptoSwiftRawRep))
       XCTAssertEqual(rsaSecKeyRawRep, try rsaCryptoSwift.publicKeyExternalRepresentation())
     }
+
+    /// From CryptoSwift RSA -> External Representation -> SecKey
+    ///
+    /// This test enforces that
+    /// 1) We can export the raw external representation of a 1 byte CryptoSwift RSA Public Key
+    /// 2) And that we can import / create an RSA SecKey from that raw external representation
+    /// 3) Proves interoperability between Apple's `Security` Framework and `CryptoSwift`
+    func testRSAExternalRepresentationPublic_1ByteExponent() throws {
+
+      // Generate a CryptoSwift RSA Key
+      let n: Array<UInt8> = [
+        0xDF, 0x74, 0xEA, 0xA8, 0xB4, 0x77, 0x79, 0xE5, 0x26, 0x0E, 0xD1, 0xD2, 0xF3, 0xDA, 0x85, 0xDE,
+        0x9E, 0x0C, 0x3F, 0xB5, 0x9F, 0xAA, 0xDD, 0x99, 0x8E, 0x3D, 0xE5, 0x66, 0x32, 0xE3, 0x8C, 0x21,
+        0x83, 0xBF, 0x0A, 0xFD, 0x70, 0x93, 0x65, 0x34, 0x38, 0xAE, 0x29, 0xBA, 0x0E, 0x0E, 0x05, 0x22,
+        0x4F, 0x86, 0x5D, 0x3D, 0x66, 0xCE, 0x88, 0xC0, 0x1F, 0x0D, 0xC0, 0xF3, 0x94, 0xEC, 0x40, 0xD3,
+        0x80, 0xC3, 0x9C, 0x41, 0x46, 0x01, 0xFF, 0xA4, 0x0D, 0x08, 0x8D, 0x49, 0xED, 0x99, 0xB6, 0xA0,
+        0xBB, 0x6E, 0x72, 0x1C, 0xF3, 0xE2, 0x92, 0x1B, 0xFA, 0x8E, 0x19, 0x02, 0x15, 0x69, 0xAC, 0xB8,
+        0x51, 0xCA, 0xFA, 0xA2, 0xF0, 0xE4, 0xCA, 0x43, 0xB9, 0x1F, 0x19, 0xFB, 0x39, 0x4E, 0xEC, 0x26,
+        0x9F, 0x53, 0x3F, 0xD1, 0xF4, 0x24, 0x7F, 0x33, 0x31, 0x00, 0x3A, 0x63, 0x38, 0xA3, 0x60, 0x7F,
+        0x4B, 0xB2, 0xEA, 0x53, 0x7A, 0xBA, 0xD8, 0xDD, 0x4E, 0xB3, 0xCA, 0x28, 0x55, 0x10, 0x35, 0xD7,
+        0x3A, 0xFD, 0x3C, 0xBC, 0x11, 0xE4, 0xE7, 0x40, 0x4C, 0x14, 0x96, 0xC4, 0xF6, 0x2C, 0x05, 0xC2,
+        0x7C, 0x42, 0xB1, 0x4E, 0x7E, 0x51, 0x95, 0x19, 0x63, 0x0F, 0x3B, 0x52, 0xED, 0x27, 0xE0, 0xB3,
+        0xC5, 0x4B, 0xD0, 0x53, 0xF2, 0xD5, 0x08, 0xBC, 0x07, 0xE7, 0x45, 0x72, 0x04, 0x58, 0x28, 0x5A,
+        0xDC, 0xA6, 0xC5, 0x5A, 0x67, 0x59, 0x41, 0x99, 0x72, 0xAC, 0x5C, 0x34, 0x6E, 0xE5, 0x04, 0x7F,
+        0x46, 0x0D, 0xDF, 0xF4, 0x34, 0x6A, 0xE0, 0x64, 0x75, 0xB0, 0xD1, 0xFC, 0x44, 0xB6, 0x3D, 0xB8,
+        0x0A, 0x4C, 0x97, 0x64, 0x8D, 0xCF, 0xEB, 0x11, 0xE3, 0x34, 0x4F, 0x1B, 0xCE, 0x51, 0xFE, 0xC7,
+        0xB9, 0x43, 0x4E, 0x86, 0xBB, 0x40, 0x54, 0x43, 0x75, 0x0F, 0x9B, 0xAE, 0xC4, 0x4D, 0x56, 0x4B
+      ]
+
+      let e: Array<UInt8> = [
+        0x03
+      ]
 
+      let rsaCryptoSwift = RSA(n: n, e: e)
+
+      // Get the key's rawExternalRepresentation
+      let rsaCryptoSwiftRawRep = try rsaCryptoSwift.publicKeyDER()
+
+      // We should be able to instantiate an RSA SecKey from this data
+      let attributes: [String: Any] = [
+        kSecAttrKeyType as String: kSecAttrKeyTypeRSA,
+        kSecAttrKeyClass as String: kSecAttrKeyClassPublic,
+        kSecAttrKeySizeInBits as String: 2048,
+        kSecAttrIsPermanent as String: false
+      ]
+      var error: Unmanaged<CFError>?
+      guard let rsaSecKey = SecKeyCreateWithData(Data(rsaCryptoSwiftRawRep) as CFData, attributes as CFDictionary, &error) else {
+        XCTFail("Error constructing SecKey from raw key data: \(error.debugDescription)")
+        return
+      }
+
+      // Get the SecKey's external representation
+      var externalRepError: Unmanaged<CFError>?
+      guard let rsaSecKeyRawRep = SecKeyCopyExternalRepresentation(rsaSecKey, &externalRepError) as? Data else {
+        XCTFail("Failed to copy external representation for RSA SecKey")
+        return
+      }
+
+      // Ensure both the CryptoSwift Ext Rep and the SecKey Ext Rep match
+      XCTAssertEqual(rsaSecKeyRawRep, Data(rsaCryptoSwiftRawRep))
+      XCTAssertEqual(rsaSecKeyRawRep, try rsaCryptoSwift.publicKeyExternalRepresentation())
+    }
+
     /// From CryptoSwift RSA -> External Representation -> SecKey
     ///
     /// This test enforces that