diff --git a/generation/src/Add.hs b/generation/src/Add.hs
index 2542221..2e52b25 100644
--- a/generation/src/Add.hs
+++ b/generation/src/Add.hs
@@ -38,8 +38,8 @@ unsafeAddOps = File {
     testCase = Just generateUnsafeTests
 }
 
-declareSafeAddOperators :: Word -> SourceFile Span
-declareSafeAddOperators bitsize =
+declareSafeAddOperators :: Word -> [Word] -> SourceFile Span
+declareSafeAddOperators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       dname = mkIdent ("U" ++ show (bitsize + 64))
       fullRippleAdd = makeRippleAdder True (bitsize `div` 64) "res"
@@ -115,8 +115,8 @@ declareSafeAddOperators bitsize =
       }
       |]
 
-declareUnsafeAddOperators :: Word -> SourceFile Span
-declareUnsafeAddOperators bitsize =
+declareUnsafeAddOperators :: Word -> [Word] -> SourceFile Span
+declareUnsafeAddOperators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       fullRippleAdd = makeRippleAdder False (bitsize `div` 64) "self"
       testFileLit = Lit [] (Str (testFile bitsize) Cooked Unsuffixed mempty) mempty
diff --git a/generation/src/Base.hs b/generation/src/Base.hs
index 955f54a..99caf7b 100644
--- a/generation/src/Base.hs
+++ b/generation/src/Base.hs
@@ -20,8 +20,8 @@ base = File {
   testCase = Nothing
 }
 
-declareBaseStructure :: Word -> SourceFile Span
-declareBaseStructure bitsize =
+declareBaseStructure :: Word -> [Word] -> SourceFile Span
+declareBaseStructure bitsize _ =
   let tname = "U" ++ show bitsize
       entries = bitsize `div` 64
       sname = mkIdent tname
diff --git a/generation/src/BinaryOps.hs b/generation/src/BinaryOps.hs
index ff7b2f2..e999a60 100644
--- a/generation/src/BinaryOps.hs
+++ b/generation/src/BinaryOps.hs
@@ -28,8 +28,8 @@ binaryOps = File {
     testCase = Just generateTests
 }
 
-declareBinaryOperators :: Word -> SourceFile Span
-declareBinaryOperators bitsize =
+declareBinaryOperators :: Word -> [Word] -> SourceFile Span
+declareBinaryOperators bitsize _ =
   let struct_name = mkIdent ("U" ++ show bitsize)
       entries = bitsize `div` 64
       andOps = generateBinOps "BitAnd" struct_name "bitand" BitAndOp entries
diff --git a/generation/src/Compare.hs b/generation/src/Compare.hs
index 9ebd39a..017fcd9 100644
--- a/generation/src/Compare.hs
+++ b/generation/src/Compare.hs
@@ -24,8 +24,8 @@ comparisons = File {
   testCase = Just generateTests
 }
 
-declareComparators :: Word -> SourceFile Span
-declareComparators bitsize =
+declareComparators :: Word -> [Word] -> SourceFile Span
+declareComparators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       entries = bitsize `div` 64
       eqStatements = buildEqStatements 0 entries
diff --git a/generation/src/Conversions.hs b/generation/src/Conversions.hs
index 99e890c..b3f8804 100644
--- a/generation/src/Conversions.hs
+++ b/generation/src/Conversions.hs
@@ -20,8 +20,8 @@ conversions = File {
   testCase = Nothing
 }
 
-declareConversions :: Word -> SourceFile Span
-declareConversions bitsize =
+declareConversions :: Word -> [Word] -> SourceFile Span
+declareConversions bitsize otherSizes =
   let sname      = mkIdent ("U" ++ show bitsize)
       entries    = bitsize `div` 64
       u8_prims   = buildPrimitives sname (mkIdent "u8")  entries
@@ -36,13 +36,14 @@ declareConversions bitsize =
       i64_prims  = generateSignedPrims sname (mkIdent "u64") (mkIdent "i64")
       isz_prims  = buildPrimitives sname (mkIdent "isize") entries
       i128_prims = generateI128Primitives sname
+      others     = generateCryptonumConversions bitsize otherSizes
   in [sourceFile|
        use core::convert::{From,TryFrom};
        use crate::CryptoNum;
        use crate::ConversionError;
        #[cfg(test)]
        use quickcheck::quickcheck;
-       use super::$$sname;
+       use super::super::*;
 
        $@{u8_prims}
        $@{u16_prims}
@@ -58,6 +59,8 @@ declareConversions bitsize =
        $@{isz_prims}
        $@{i128_prims}
 
+       $@{others}
+
        #[cfg(test)]
        quickcheck! {
          fn u8_recovers(x: u8) -> bool {
@@ -244,3 +247,60 @@ generateI128Primitives sname = [
       }
     }|]
    ]
+
+generateCryptonumConversions :: Word -> [Word] -> [Item Span]
+generateCryptonumConversions source otherSizes = concatMap convert otherSizes
+ where
+   sName = mkIdent ("U" ++ show source)
+   --
+   convert target =
+     let tName = mkIdent ("U" ++ show target)
+         sEntries = toLit (source `div` 64)
+         tEntries = toLit (target `div` 64)
+     in case compare source target of
+          LT -> [
+            [item| 
+             impl<'a> From<&'a $$sName> for $$tName {
+               fn from(x: &$$sName) -> $$tName {
+                 let mut res = $$tName::zero();
+                 res.value[0..$$(sEntries)].copy_from_slice(&x.value);
+                 res
+               }
+             }
+            |],
+            [item|
+             impl From<$$sName> for $$tName {
+               fn from(x: $$sName) -> $$tName {
+                 $$tName::from(&x)
+               }
+             }
+            |]
+            ]
+          EQ -> []
+          GT -> [
+            [item|
+              impl<'a> TryFrom<&'a $$sName> for $$tName {
+                type Error = ConversionError;
+
+                fn try_from(x: &$$sName) -> Result<$$tName, ConversionError> {
+                  if x.value.iter().skip($$(tEntries)).all(|x| *x == 0) {
+                    let mut res = $$tName::zero();
+                    res.value.copy_from_slice(&x.value[0..$$(tEntries)]);
+                    Ok(res)
+                  } else {
+                    Err(ConversionError::Overflow)
+                  }
+                }
+              }
+            |],
+            [item|
+              impl TryFrom<$$sName> for $$tName {
+                type Error = ConversionError;
+
+                fn try_from(x: $$sName) -> Result<$$tName, ConversionError> {
+                  $$tName::try_from(&x)
+                }
+              }
+            |]
+            ]
+          
\ No newline at end of file
diff --git a/generation/src/CryptoNum.hs b/generation/src/CryptoNum.hs
index c9145b8..3305834 100644
--- a/generation/src/CryptoNum.hs
+++ b/generation/src/CryptoNum.hs
@@ -28,8 +28,8 @@ cryptoNum = File {
   testCase = Just generateTests
 }
 
-declareCryptoNumInstance :: Word -> SourceFile Span
-declareCryptoNumInstance bitsize =
+declareCryptoNumInstance :: Word -> [Word] -> SourceFile Span
+declareCryptoNumInstance bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       entries = bitsize `div` 64
       entlit = Lit [] (Int Dec (fromIntegral entries) Unsuffixed mempty) mempty
diff --git a/generation/src/Division.hs b/generation/src/Division.hs
index fc61412..f6bdff3 100644
--- a/generation/src/Division.hs
+++ b/generation/src/Division.hs
@@ -25,8 +25,8 @@ divisionOps = File {
     testCase = Just generateDivisionTests
 }
 
-declareDivision :: Word -> SourceFile Span
-declareDivision size =
+declareDivision :: Word -> [Word] -> SourceFile Span
+declareDivision size _ =
     let sname = mkIdent ("U" ++ show size)
         entries = size `div` 64
         copyAssign = map doCopy [0..entries-1]
diff --git a/generation/src/File.hs b/generation/src/File.hs
index fe606c5..c86774e 100644
--- a/generation/src/File.hs
+++ b/generation/src/File.hs
@@ -26,7 +26,7 @@ data File = File {
     predicate :: Word -> [Word] -> Bool,
     outputName :: FilePath,
     isUnsigned :: Bool,
-    generator :: Word -> SourceFile Span,
+    generator :: Word -> [Word] -> SourceFile Span,
     testCase :: forall g. RandomGen g => Maybe (Word -> g -> [Map String String])
 }
 
@@ -62,7 +62,7 @@ generateTasks rng files sizes = basicTasks ++ moduleTasks
             mainTask = Task {
               outputFile = "src" </> signedBit </> ("u" ++ show size) </>
                            outputName file ++ ".rs",
-              writer = \ hndl -> writeSourceFile hndl (generator file size)
+              writer = \ hndl -> writeSourceFile hndl (generator file size sizes)
             }
         in case testCase file of
              Nothing ->
diff --git a/generation/src/Karatsuba.hs b/generation/src/Karatsuba.hs
index 59933c2..c7a173a 100644
--- a/generation/src/Karatsuba.hs
+++ b/generation/src/Karatsuba.hs
@@ -7,6 +7,7 @@
 module Karatsuba(
          Instruction(..)
        , runChecks
+       , runQuickCheck
        , generateInstructions
        )
  where
diff --git a/generation/src/ModOps.hs b/generation/src/ModOps.hs
index a4e421d..42bc935 100644
--- a/generation/src/ModOps.hs
+++ b/generation/src/ModOps.hs
@@ -26,8 +26,8 @@ modulusOps = File {
     testCase = Just generateModulusTests
 }
 
-declareModOps :: Word -> SourceFile Span
-declareModOps bitsize =
+declareModOps :: Word -> [Word] -> SourceFile Span
+declareModOps bitsize _ =
     let sname = mkIdent ("U" ++ show bitsize)
         bname = mkIdent ("U" ++ show (bitsize * 2))
     in [sourceFile| 
diff --git a/generation/src/Multiply.hs b/generation/src/Multiply.hs
index 11ee4b3..7295861 100644
--- a/generation/src/Multiply.hs
+++ b/generation/src/Multiply.hs
@@ -40,8 +40,8 @@ unsafeMultiplyOps = File {
     testCase = Just generateUnsafeTests
 }
 
-declareSafeMulOperators :: Word -> SourceFile Span
-declareSafeMulOperators bitsize =
+declareSafeMulOperators :: Word -> [Word] -> SourceFile Span
+declareSafeMulOperators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       dname = mkIdent ("U" ++ show (bitsize * 2))
       fullRippleMul = generateMultiplier True (bitsize `div` 64) "rhs" "res"
@@ -117,8 +117,8 @@ declareSafeMulOperators bitsize =
       }
       |]
 
-declareUnsafeMulOperators :: Word -> SourceFile Span
-declareUnsafeMulOperators bitsize =
+declareUnsafeMulOperators :: Word -> [Word] -> SourceFile Span
+declareUnsafeMulOperators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       halfRippleMul = generateMultiplier False (bitsize `div` 64) "rhs" "self"
       testFileLit = Lit [] (Str (testFile bitsize) Cooked Unsuffixed mempty) mempty
diff --git a/generation/src/Scale.hs b/generation/src/Scale.hs
index c321382..2049e40 100644
--- a/generation/src/Scale.hs
+++ b/generation/src/Scale.hs
@@ -38,8 +38,8 @@ unsafeScaleOps = File {
     testCase = Just generateUnsafeTests
 }
 
-declareSafeScaleOperators :: Word -> SourceFile Span
-declareSafeScaleOperators bitsize =
+declareSafeScaleOperators :: Word -> [Word] -> SourceFile Span
+declareSafeScaleOperators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       dname = mkIdent ("U" ++ show (bitsize + 64))
       fullRippleScale = generateScaletiplier True (bitsize `div` 64) "rhs" "res"
@@ -154,8 +154,8 @@ declareSafeScaleOperators bitsize =
       }
       |]
 
-declareUnsafeScaleOperators :: Word -> SourceFile Span
-declareUnsafeScaleOperators bitsize =
+declareUnsafeScaleOperators :: Word -> [Word] -> SourceFile Span
+declareUnsafeScaleOperators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       halfRippleScale = generateScaletiplier False (bitsize `div` 64) "rhs" "self"
       testFileLit = Lit [] (Str (testFile bitsize) Cooked Unsuffixed mempty) mempty
diff --git a/generation/src/Shift.hs b/generation/src/Shift.hs
index 45492a4..5b85554 100644
--- a/generation/src/Shift.hs
+++ b/generation/src/Shift.hs
@@ -26,8 +26,8 @@ shiftOps = File {
     testCase = Just generateTests
 }
 
-declareShiftOperators :: Word -> SourceFile Span
-declareShiftOperators bitsize =
+declareShiftOperators :: Word -> [Word] -> SourceFile Span
+declareShiftOperators bitsize _ =
   let struct_name = mkIdent ("U" ++ show bitsize)
       entries = bitsize `div` 64
       unsignedShifts = generateUnsigneds struct_name
diff --git a/generation/src/Subtract.hs b/generation/src/Subtract.hs
index 7867d40..0498dff 100644
--- a/generation/src/Subtract.hs
+++ b/generation/src/Subtract.hs
@@ -38,8 +38,8 @@ unsafeSubtractOps = File {
     testCase = Just generateUnsafeTests
 }
 
-declareSafeSubtractOperators :: Word -> SourceFile Span
-declareSafeSubtractOperators bitsize =
+declareSafeSubtractOperators :: Word -> [Word] -> SourceFile Span
+declareSafeSubtractOperators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       dname = mkIdent ("U" ++ show (bitsize + 64))
       fullRippleSubtract = makeRippleSubtracter True (bitsize `div` 64) "res"
@@ -106,8 +106,8 @@ declareSafeSubtractOperators bitsize =
       }
       |]
 
-declareUnsafeSubtractOperators :: Word -> SourceFile Span
-declareUnsafeSubtractOperators bitsize =
+declareUnsafeSubtractOperators :: Word -> [Word] -> SourceFile Span
+declareUnsafeSubtractOperators bitsize _ =
   let sname = mkIdent ("U" ++ show bitsize)
       fullRippleSubtract = makeRippleSubtracter False (bitsize `div` 64) "self"
       testFileLit = Lit [] (Str (testFile bitsize) Cooked Unsuffixed mempty) mempty