Remove *SafeGcdInverter types from public API

Previously they needed to be public to make trait bounds work, but now
that those bounds are no longer required (#894) these types no longer
need to be public, as they're otherwise an implementation detail.

Author: tarcieri

src/modular.rs

@@ -36,14 +36,12 @@ pub use self::{
     const_monty_form::{ConstMontyForm, ConstMontyParams, invert::ConstMontyFormInverter},
     monty_form::{MontyForm, MontyParams},
     reduction::montgomery_reduction,
-    safegcd::SafeGcdInverter,
 };
 
+pub(crate) use self::safegcd::SafeGcdInverter;
+
 #[cfg(feature = "alloc")]
-pub use self::{
-    boxed_monty_form::{BoxedMontyForm, BoxedMontyParams},
-    safegcd::boxed::BoxedSafeGcdInverter,
-};
+pub use self::boxed_monty_form::{BoxedMontyForm, BoxedMontyParams};
 
 /// A generalization for numbers kept in optimized representations (e.g. Montgomery)
 /// that can be converted back to the original form.

src/modular/boxed_monty_form/invert.rs

@@ -1,7 +1,7 @@
 //! Multiplicative inverses of boxed integers in Montgomery form.
 
 use super::{BoxedMontyForm, BoxedMontyParams};
-use crate::{Invert, modular::BoxedSafeGcdInverter};
+use crate::{Invert, modular::safegcd::boxed::BoxedSafeGcdInverter};
 use subtle::CtOption;
 
 impl BoxedMontyForm {

src/modular/safegcd.rs

@@ -46,7 +46,7 @@ const GCD_BATCH_SIZE: u32 = 62;
 /// - P. Wuille, "The safegcd implementation in libsecp256k1 explained",
 ///   <https://github.com/bitcoin-core/secp256k1/blob/master/doc/safegcd_implementation.md>
 #[derive(Clone, Debug)]
-pub struct SafeGcdInverter<const LIMBS: usize> {
+pub(crate) struct SafeGcdInverter<const LIMBS: usize> {
     /// Modulus
     pub(super) modulus: Odd<Uint<LIMBS>>,
 
@@ -62,9 +62,8 @@ type Matrix = [[i64; 2]; 2];
 
 impl<const LIMBS: usize> SafeGcdInverter<LIMBS> {
     /// Creates the inverter for specified modulus and adjusting parameter.
-    ///
-    /// Modulus must be odd. Returns `None` if it is not.
-    pub const fn new(modulus: &Odd<Uint<LIMBS>>, adjuster: &Uint<LIMBS>) -> Self {
+    #[cfg(test)]
+    pub(crate) const fn new(modulus: &Odd<Uint<LIMBS>>, adjuster: &Uint<LIMBS>) -> Self {
         Self::new_with_inverse(
             modulus,
             U64::from_u64(invert_mod_u64(modulus.as_ref().as_words())),
@@ -85,28 +84,12 @@ impl<const LIMBS: usize> SafeGcdInverter<LIMBS> {
         }
     }
 
-    /// Returns either the adjusted modular multiplicative inverse for the argument or `None`
-    /// depending on invertibility of the argument, i.e. its coprimality with the modulus.
-    #[deprecated(since = "0.7.0", note = "please use `invert` instead")]
-    pub const fn inv(&self, value: &Uint<LIMBS>) -> ConstCtOption<Uint<LIMBS>> {
-        self.invert(value)
-    }
-
     /// Returns either the adjusted modular multiplicative inverse for the argument or `None`
     /// depending on invertibility of the argument, i.e. its coprimality with the modulus.
     pub const fn invert(&self, value: &Uint<LIMBS>) -> ConstCtOption<Uint<LIMBS>> {
         invert_odd_mod_precomp::<LIMBS, false>(value, &self.modulus, self.inverse, &self.adjuster)
     }
 
-    /// Returns either the adjusted modular multiplicative inverse for the argument or `None`
-    /// depending on invertibility of the argument, i.e. its coprimality with the modulus.
-    ///
-    /// This version is variable-time with respect to `value`.
-    #[deprecated(since = "0.7.0", note = "please use `invert_vartime` instead")]
-    pub const fn inv_vartime(&self, value: &Uint<LIMBS>) -> ConstCtOption<Uint<LIMBS>> {
-        self.invert_vartime(value)
-    }
-
     /// Returns either the adjusted modular multiplicative inverse for the argument or `None`
     /// depending on invertibility of the argument, i.e. its coprimality with the modulus.
     ///

src/modular/safegcd/boxed.rs

@@ -16,7 +16,7 @@ use subtle::{Choice, CtOption};
 ///
 /// See [`super::SafeGcdInverter`] for more information.
 #[derive(Clone, Debug)]
-pub struct BoxedSafeGcdInverter {
+pub(crate) struct BoxedSafeGcdInverter {
     /// Modulus
     pub(crate) modulus: Odd<BoxedUint>,
 
@@ -31,6 +31,7 @@ impl BoxedSafeGcdInverter {
     /// Creates the inverter for specified modulus and adjusting parameter.
     ///
     /// Modulus must be odd. Returns `None` if it is not.
+    #[cfg(test)]
     pub fn new(modulus: Odd<BoxedUint>, adjuster: BoxedUint) -> Self {
         let inverse = U64::from_u64(invert_mod_u64(modulus.as_ref().as_words()));
         Self::new_with_inverse(modulus, inverse, adjuster)

tests/safegcd.rs

@@ -3,7 +3,7 @@
 mod common;
 
 use common::to_biguint;
-use crypto_bigint::{Odd, U256, Uint, modular::SafeGcdInverter};
+use crypto_bigint::{Odd, U256};
 use num_bigint::BigUint;
 use num_integer::Integer;
 use num_traits::One;
@@ -64,28 +64,6 @@ proptest! {
         }
     }
 
-    #[test]
-    fn invert_precomputed(x in uint()) {
-        let x_bi = to_biguint(&x);
-        let p_bi = to_biguint(&P);
-
-        let expected_is_some = x_bi.gcd(&p_bi) == BigUint::one();
-        let inverter = SafeGcdInverter::new(&P, &Uint::ONE);
-        let actual = inverter.invert(&x);
-
-        prop_assert_eq!(expected_is_some, bool::from(actual.is_some()));
-
-        if let Some(actual) = Option::<U256>::from(actual) {
-            let inv_bi = to_biguint(&actual);
-            let res = (inv_bi * x_bi) % p_bi;
-            prop_assert_eq!(res, BigUint::one());
-
-            // check vartime implementation equivalence
-            let actual_vartime = inverter.invert_vartime(&x).unwrap();
-            prop_assert_eq!(actual, actual_vartime);
-        }
-    }
-
     #[cfg(feature = "alloc")]
     #[test]
     fn boxed_invert_mod(x in boxed_uint()) {