Start on error + BN refactor

1 files changed, 1003 insertions, 0 deletions

diff --git a/openssl/src/bn.rs b/openssl/src/bn.rs
new file mode 100644
index 00000000..22924e67
--- /dev/null
+++ b/openssl/src/bn.rs
@@ -0,0 +1,1003 @@
+use ffi;
+use libc::{c_int, c_void};
+use std::cmp::Ordering;
+use std::ffi::{CStr, CString};
+use std::{fmt, ptr};
+use std::marker::PhantomData;
+use std::ops::{Add, Div, Mul, Neg, Rem, Shl, Shr, Sub, Deref, DerefMut};
+
+use {cvt, cvt_p, cvt_n};
+use error::ErrorStack;
+
+/// Specifies the desired properties of a randomly generated `BigNum`.
+#[derive(Copy, Clone)]
+#[repr(C)]
+pub enum RNGProperty {
+    /// The most significant bit of the number is allowed to be 0.
+    MsbMaybeZero = -1,
+    /// The MSB should be set to 1.
+    MsbOne = 0,
+    /// The two most significant bits of the number will be set to 1, so that the product of two
+    /// such random numbers will always have `2 * bits` length.
+    TwoMsbOne = 1,
+}
+
+macro_rules! with_ctx(
+    ($name:ident, $action:block) => ({
+        let $name = ffi::BN_CTX_new();
+        if ($name).is_null() {
+            Err(ErrorStack::get())
+        } else {
+            let r = $action;
+            ffi::BN_CTX_free($name);
+            r
+        }
+    });
+);
+
+macro_rules! with_bn(
+    ($name:ident, $action:block) => ({
+        let tmp = BigNum::new();
+        match tmp {
+            Ok($name) => {
+                if $action {
+                    Ok($name)
+                } else {
+                    Err(ErrorStack::get())
+                }
+            },
+            Err(err) => Err(err),
+        }
+    });
+);
+
+macro_rules! with_bn_in_ctx(
+    ($name:ident, $ctx_name:ident, $action:block) => ({
+        let tmp = BigNum::new();
+        match tmp {
+            Ok($name) => {
+                let $ctx_name = ffi::BN_CTX_new();
+                if ($ctx_name).is_null() {
+                    Err(ErrorStack::get())
+                } else {
+                    let r =
+                        if $action {
+                            Ok($name)
+                        } else {
+                            Err(ErrorStack::get())
+                        };
+                    ffi::BN_CTX_free($ctx_name);
+                    r
+                }
+            },
+            Err(err) => Err(err),
+        }
+    });
+);
+
+/// A context object for `BigNum` operations.
+pub struct BnCtx(*mut ffi::BN_CTX);
+
+impl Drop for BnCtx {
+    fn drop(&mut self) {
+        unsafe {
+            ffi::BN_CTX_free(self.0);
+        }
+    }
+}
+
+impl BnCtx {
+    /// Returns a new `BnCtx`.
+    pub fn new() -> Result<BnCtx, ErrorStack> {
+        unsafe {
+            cvt_p(ffi::BN_CTX_new()).map(BnCtx)
+        }
+    }
+
+    /// Places the result of `a²` in `r`.
+    pub fn sqr(&mut self, r: &mut BigNumRef, a: &BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_sqr(r.as_ptr(), a.as_ptr(), self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the result of `a mod m` in `r`.
+    pub fn nnmod(&mut self,
+                 r: &mut BigNumRef,
+                 a: &BigNumRef,
+                 m: &BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_nnmod(r.as_ptr(), a.as_ptr(), m.as_ptr(), self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the result of `(a + b) mod m` in `r`.
+    pub fn mod_add(&mut self,
+                   r: &mut BigNumRef,
+                   a: &BigNumRef,
+                   b: &BigNumRef,
+                   m: &BigNumRef)
+                   -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_mod_add(r.as_ptr(), a.as_ptr(), b.as_ptr(), m.as_ptr(), self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the result of `(a - b) mod m` in `r`.
+    pub fn mod_sub(&mut self,
+                   r: &mut BigNumRef,
+                   a: &BigNumRef,
+                   b: &BigNumRef,
+                   m: &BigNumRef)
+                   -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_mod_sub(r.as_ptr(), a.as_ptr(), b.as_ptr(), m.as_ptr(), self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the result of `(a * b) mod m` in `r`.
+    pub fn mod_mul(&mut self,
+                   r: &mut BigNumRef,
+                   a: &BigNumRef,
+                   b: &BigNumRef,
+                   m: &BigNumRef)
+                   -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_mod_mul(r.as_ptr(), a.as_ptr(), b.as_ptr(), m.as_ptr(), self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the result of `a² mod m` in `r`.
+    pub fn mod_sqr(&mut self,
+                   r: &mut BigNumRef,
+                   a: &BigNumRef,
+                   m: &BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_mod_sqr(r.as_ptr(), a.as_ptr(), m.as_ptr(), self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the result of `a^p` in `r`.
+    pub fn exp(&mut self,
+               r: &mut BigNumRef,
+               a: &BigNumRef,
+               p: &BigNumRef) -> Result<(), ErrorStack> {
+        unsafe{
+            cvt(ffi::BN_exp(r.as_ptr(), a.as_ptr(), p.as_ptr(), self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the result of `a^p mod m` in `r`.
+    pub fn mod_exp(&mut self,
+                   r: &mut BigNumRef,
+                   a: &BigNumRef,
+                   p: &BigNumRef,
+                   m: &BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_mod_exp(r.as_ptr(), a.as_ptr(), p.as_ptr(), m.as_ptr(), self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the inverse of `a` modulo `n` in `r`.
+    pub fn mod_inverse(&mut self,
+                       r: &mut BigNumRef,
+                       a: &BigNumRef,
+                       n: &BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt_p(ffi::BN_mod_inverse(r.0, a.0, n.0, self.0)).map(|_| ())
+        }
+    }
+
+    /// Places the greatest common denominator of `a` and `b` in `r`.
+    pub fn gcd(&mut self,
+               r: &mut BigNumRef,
+               a: &BigNumRef,
+               b: &BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_gcd(r.0, a.0, b.0, self.0)).map(|_| ())
+        }
+    }
+
+    /// Checks whether `p` is prime.
+    ///
+    /// Performs a Miller-Rabin probabilistic primality test with `checks` iterations.
+    ///
+    /// Returns `true` if `p` is prime with an error probability of less than `0.25 ^ checks`.
+    pub fn is_prime(&mut self, p: &BigNumRef, checks: i32) -> Result<bool, ErrorStack> {
+        unsafe {
+            cvt_n(ffi::BN_is_prime_ex(p.0, checks.into(), self.0, ptr::null_mut())).map(|r| r != 0)
+        }
+    }
+
+    /// Checks whether `p` is prime with optional trial division.
+    ///
+    /// If `do_trial_division` is `true`, first performs trial division by a number of small primes.
+    /// Then, like `is_prime`, performs a Miller-Rabin probabilistic primality test with `checks`
+    /// iterations.
+    ///
+    /// # Return Value
+    ///
+    /// Returns `true` if `p` is prime with an error probability of less than `0.25 ^ checks`.
+    pub fn is_prime_fasttest(&mut self,
+                             p: &BigNumRef,
+                             checks: i32,
+                             do_trial_division: bool) -> Result<bool, ErrorStack> {
+        unsafe {
+            cvt_n(ffi::BN_is_prime_fasttest_ex(p.0,
+                                               checks.into(),
+                                               self.0,
+                                               do_trial_division as c_int,
+                                               ptr::null_mut()))
+                .map(|r| r != 0)
+        }
+    }
+}
+
+/// A borrowed, signed, arbitrary-precision integer.
+#[derive(Copy, Clone)]
+pub struct BigNumRef<'a>(*mut ffi::BIGNUM, PhantomData<&'a ()>);
+
+impl<'a> BigNumRef<'a> {
+    pub unsafe fn from_ptr(handle: *mut ffi::BIGNUM) -> BigNumRef<'a> {
+        BigNumRef(handle, PhantomData)
+    }
+
+    /// Adds a `u32` to `self`.
+    pub fn add_word(&mut self, w: u32) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_add_word(self.0, w as ffi::BN_ULONG)).map(|_| ())
+        }
+    }
+
+    /// Subtracts a `u32` from `self`.
+    pub fn sub_word(&mut self, w: u32) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_sub_word(self.0, w as ffi::BN_ULONG)).map(|_| ())
+        }
+    }
+
+    /// Multiplies a `u32` by `self`.
+    pub fn mul_word(&mut self, w: u32) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_mul_word(self.0, w as ffi::BN_ULONG)).map(|_| ())
+        }
+    }
+
+    /// Divides `self` by a `u32`, returning the remainder.
+    pub fn div_word(&mut self, w: u32) -> Result<u64, ErrorStack> {
+        unsafe {
+            let r = ffi::BN_div_word(self.0, w.into());
+            if r == ffi::BN_ULONG::max_value() {
+                Err(ErrorStack::get())
+            } else {
+                Ok(r.into())
+            }
+        }
+    }
+
+    /// Returns the result of `self` modulo `w`.
+    pub fn mod_word(&self, w: u32) -> Result<u64, ErrorStack> {
+        unsafe {
+            let r = ffi::BN_mod_word(self.0, w.into());
+            if r == ffi::BN_ULONG::max_value() {
+                Err(ErrorStack::get())
+            } else {
+                Ok(r.into())
+            }
+        }
+    }
+
+    /// Places a cryptographically-secure pseudo-random number nonnegative
+    /// number less than `self` in `rnd`.
+    pub fn rand_in_range(&self, rnd: &mut BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_rand_range(self.0, rnd.0)).map(|_| ())
+        }
+    }
+
+    /// The cryptographically weak counterpart to `rand_in_range`.
+    pub fn pseudo_rand_in_range(&self, rnd: &mut BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_pseudo_rand_range(self.0, rnd.0)).map(|_| ())
+        }
+    }
+
+    /// Sets bit `n`. Equivalent to `self |= (1 << n)`.
+    ///
+    /// When setting a bit outside of `self`, it is expanded.
+    pub fn set_bit(&mut self, n: i32) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_set_bit(self.0, n.into())).map(|_| ())
+        }
+    }
+
+    /// Clears bit `n`, setting it to 0. Equivalent to `self &= ~(1 << n)`.
+    ///
+    /// When clearing a bit outside of `self`, an error is returned.
+    pub fn clear_bit(&mut self, n: i32) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_clear_bit(self.0, n.into())).map(|_| ())
+        }
+    }
+
+    /// Returns `true` if the `n`th bit of `self` is set to 1, `false` otherwise.
+    pub fn is_bit_set(&self, n: i32) -> bool {
+        unsafe {
+            ffi::BN_is_bit_set(self.0, n.into()) == 1
+        }
+    }
+
+    /// Truncates `self` to the lowest `n` bits.
+    ///
+    /// An error occurs if `self` is already shorter than `n` bits.
+    pub fn mask_bits(&mut self, n: i32) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_mask_bits(self.0, n.into())).map(|_| ())
+        }
+    }
+
+    /// Places `self << 1` in `r`.
+    pub fn lshift1(&self, r: &mut BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_lshift1(r.0, self.0)).map(|_| ())
+        }
+    }
+
+    /// Places `self >> 1` in `r`.
+    pub fn rshift1(&self, r: &mut BigNumRef) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::BN_rshift1(r.0, self.0)).map(|_| ())
+        }
+    }
+
+    pub fn checked_add(&self, a: &BigNumRef) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn!(r, {
+                ffi::BN_add(r.as_ptr(), self.as_ptr(), a.as_ptr()) == 1
+            })
+        }
+    }
+
+    pub fn checked_sub(&self, a: &BigNumRef) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn!(r, {
+                ffi::BN_sub(r.as_ptr(), self.as_ptr(), a.as_ptr()) == 1
+            })
+        }
+    }
+
+    pub fn checked_mul(&self, a: &BigNumRef) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn_in_ctx!(r, ctx, {
+                ffi::BN_mul(r.as_ptr(), self.as_ptr(), a.as_ptr(), ctx) == 1
+            })
+        }
+    }
+
+    pub fn checked_div(&self, a: &BigNumRef) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn_in_ctx!(r, ctx, {
+                ffi::BN_div(r.as_ptr(), ptr::null_mut(), self.as_ptr(), a.as_ptr(), ctx) == 1
+            })
+        }
+    }
+
+    pub fn checked_mod(&self, a: &BigNumRef) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn_in_ctx!(r, ctx, {
+                ffi::BN_div(ptr::null_mut(), r.as_ptr(), self.as_ptr(), a.as_ptr(), ctx) == 1
+            })
+        }
+    }
+
+    pub fn checked_shl(&self, a: &i32) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn!(r, {
+                ffi::BN_lshift(r.as_ptr(), self.as_ptr(), *a as c_int) == 1
+            })
+        }
+    }
+
+    pub fn checked_shr(&self, a: &i32) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn!(r, {
+                ffi::BN_rshift(r.as_ptr(), self.as_ptr(), *a as c_int) == 1
+            })
+        }
+    }
+
+    pub fn to_owned(&self) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            let r = try_ssl_null!(ffi::BN_dup(self.as_ptr()));
+            Ok(BigNum::from_ptr(r))
+        }
+    }
+
+    /// Inverts the sign of `self`.
+    ///
+    /// ```
+    /// # use openssl::bn::BigNum;
+    /// let mut s = BigNum::new_from(8).unwrap();
+    ///
+    /// s.negate();
+    /// assert_eq!(s, -BigNum::new_from(8).unwrap());
+    /// s.negate();
+    /// assert_eq!(s, BigNum::new_from(8).unwrap());
+    /// ```
+    pub fn negate(&mut self) {
+        unsafe { ffi::BN_set_negative(self.as_ptr(), !self.is_negative() as c_int) }
+    }
+
+    /// Compare the absolute values of `self` and `oth`.
+    ///
+    /// ```
+    /// # use openssl::bn::BigNum;
+    /// # use std::cmp::Ordering;
+    /// let s = -BigNum::new_from(8).unwrap();
+    /// let o = BigNum::new_from(8).unwrap();
+    ///
+    /// assert_eq!(s.abs_cmp(&o), Ordering::Equal);
+    /// ```
+    pub fn abs_cmp(&self, oth: &BigNumRef) -> Ordering {
+        unsafe {
+            let res = ffi::BN_ucmp(self.as_ptr(), oth.as_ptr()) as i32;
+            if res < 0 {
+                Ordering::Less
+            } else if res > 0 {
+                Ordering::Greater
+            } else {
+                Ordering::Equal
+            }
+        }
+    }
+
+    pub fn is_negative(&self) -> bool {
+        self._is_negative()
+    }
+
+    #[cfg(ossl10x)]
+    fn _is_negative(&self) -> bool {
+        unsafe { (*self.as_ptr()).neg == 1 }
+    }
+
+    #[cfg(ossl110)]
+    fn _is_negative(&self) -> bool {
+        unsafe { ffi::BN_is_negative(self.as_ptr()) == 1 }
+    }
+
+    /// Returns the number of significant bits in `self`.
+    pub fn num_bits(&self) -> i32 {
+        unsafe { ffi::BN_num_bits(self.as_ptr()) as i32 }
+    }
+
+    /// Returns the size of `self` in bytes.
+    pub fn num_bytes(&self) -> i32 {
+        (self.num_bits() + 7) / 8
+    }
+
+    pub fn as_ptr(&self) -> *mut ffi::BIGNUM {
+        self.0
+    }
+
+    /// Returns a big-endian byte vector representation of the absolute value of `self`.
+    ///
+    /// `self` can be recreated by using `new_from_slice`.
+    ///
+    /// ```
+    /// # use openssl::bn::BigNum;
+    /// let s = -BigNum::new_from(4543).unwrap();
+    /// let r = BigNum::new_from(4543).unwrap();
+    ///
+    /// let s_vec = s.to_vec();
+    /// assert_eq!(BigNum::new_from_slice(&s_vec).unwrap(), r);
+    /// ```
+    pub fn to_vec(&self) -> Vec<u8> {
+        let size = self.num_bytes() as usize;
+        let mut v = Vec::with_capacity(size);
+        unsafe {
+            ffi::BN_bn2bin(self.as_ptr(), v.as_mut_ptr());
+            v.set_len(size);
+        }
+        v
+    }
+
+    /// Returns a decimal string representation of `self`.
+    ///
+    /// ```
+    /// # use openssl::bn::BigNum;
+    /// let s = -BigNum::new_from(12345).unwrap();
+    ///
+    /// assert_eq!(s.to_dec_str(), "-12345");
+    /// ```
+    pub fn to_dec_str(&self) -> String {
+        unsafe {
+            let buf = ffi::BN_bn2dec(self.as_ptr());
+            assert!(!buf.is_null());
+            let str = String::from_utf8(CStr::from_ptr(buf as *const _).to_bytes().to_vec())
+                          .unwrap();
+            CRYPTO_free!(buf as *mut c_void);
+            str
+        }
+    }
+
+    /// Returns a hexadecimal string representation of `self`.
+    ///
+    /// ```
+    /// # use openssl::bn::BigNum;
+    /// let s = -BigNum::new_from(0x99ff).unwrap();
+    ///
+    /// assert_eq!(s.to_hex_str(), "-99FF");
+    /// ```
+    pub fn to_hex_str(&self) -> String {
+        unsafe {
+            let buf = ffi::BN_bn2hex(self.as_ptr());
+            assert!(!buf.is_null());
+            let str = String::from_utf8(CStr::from_ptr(buf as *const _).to_bytes().to_vec())
+                          .unwrap();
+            CRYPTO_free!(buf as *mut c_void);
+            str
+        }
+    }
+}
+
+/// An owned, signed, arbitrary-precision integer.
+///
+/// `BigNum` provides wrappers around OpenSSL's checked arithmetic functions.
+/// Additionally, it implements the standard operators (`std::ops`), which
+/// perform unchecked arithmetic, unwrapping the returned `Result` of the
+/// checked operations.
+pub struct BigNum(BigNumRef<'static>);
+
+impl BigNum {
+    /// Creates a new `BigNum` with the value 0.
+    pub fn new() -> Result<BigNum, ErrorStack> {
+        unsafe {
+            ffi::init();
+            let v = try_ssl_null!(ffi::BN_new());
+            Ok(BigNum::from_ptr(v))
+        }
+    }
+
+    /// Creates a new `BigNum` with the given value.
+    pub fn new_from(n: u32) -> Result<BigNum, ErrorStack> {
+        BigNum::new().and_then(|v| unsafe {
+            try_ssl!(ffi::BN_set_word(v.as_ptr(), n as ffi::BN_ULONG));
+            Ok(v)
+        })
+    }
+
+    /// Creates a `BigNum` from a decimal string.
+    pub fn from_dec_str(s: &str) -> Result<BigNum, ErrorStack> {
+        BigNum::new().and_then(|mut v| unsafe {
+            let c_str = CString::new(s.as_bytes()).unwrap();
+            try_ssl!(ffi::BN_dec2bn(&mut (v.0).0, c_str.as_ptr() as *const _));
+            Ok(v)
+        })
+    }
+
+    /// Creates a `BigNum` from a hexadecimal string.
+    pub fn from_hex_str(s: &str) -> Result<BigNum, ErrorStack> {
+        BigNum::new().and_then(|mut v| unsafe {
+            let c_str = CString::new(s.as_bytes()).unwrap();
+            try_ssl!(ffi::BN_hex2bn(&mut (v.0).0, c_str.as_ptr() as *const _));
+            Ok(v)
+        })
+    }
+
+    pub unsafe fn from_ptr(handle: *mut ffi::BIGNUM) -> BigNum {
+        BigNum(BigNumRef::from_ptr(handle))
+    }
+
+    /// Creates a new `BigNum` from an unsigned, big-endian encoded number of arbitrary length.
+    ///
+    /// ```
+    /// # use openssl::bn::BigNum;
+    /// let bignum = BigNum::new_from_slice(&[0x12, 0x00, 0x34]).unwrap();
+    ///
+    /// assert_eq!(bignum, BigNum::new_from(0x120034).unwrap());
+    /// ```
+    pub fn new_from_slice(n: &[u8]) -> Result<BigNum, ErrorStack> {
+        BigNum::new().and_then(|v| unsafe {
+            try_ssl_null!(ffi::BN_bin2bn(n.as_ptr(), n.len() as c_int, v.as_ptr()));
+            Ok(v)
+        })
+    }
+    /// Generates a prime number.
+    ///
+    /// # Parameters
+    ///
+    /// * `bits`: The length of the prime in bits (lower bound).
+    /// * `safe`: If true, returns a "safe" prime `p` so that `(p-1)/2` is also prime.
+    /// * `add`/`rem`: If `add` is set to `Some(add)`, `p % add == rem` will hold, where `p` is the
+    ///   generated prime and `rem` is `1` if not specified (`None`).
+    pub fn checked_generate_prime(bits: i32,
+                                  safe: bool,
+                                  add: Option<&BigNum>,
+                                  rem: Option<&BigNum>)
+                                  -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn_in_ctx!(r, ctx, {
+                let add_arg = add.map(|a| a.as_ptr()).unwrap_or(ptr::null_mut());
+                let rem_arg = rem.map(|r| r.as_ptr()).unwrap_or(ptr::null_mut());
+
+                ffi::BN_generate_prime_ex(r.as_ptr(),
+                                          bits as c_int,
+                                          safe as c_int,
+                                          add_arg,
+                                          rem_arg,
+                                          ptr::null_mut()) == 1
+            })
+        }
+    }
+
+    /// Generates a cryptographically strong pseudo-random `BigNum`.
+    ///
+    /// # Parameters
+    ///
+    /// * `bits`: Length of the number in bits.
+    /// * `prop`: The desired properties of the number.
+    /// * `odd`: If `true`, the generated number will be odd.
+    pub fn checked_new_random(bits: i32, prop: RNGProperty, odd: bool) -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn_in_ctx!(r, ctx, {
+                ffi::BN_rand(r.as_ptr(), bits as c_int, prop as c_int, odd as c_int) == 1
+            })
+        }
+    }
+
+    /// The cryptographically weak counterpart to `checked_new_random`.
+    pub fn checked_new_pseudo_random(bits: i32,
+                                     prop: RNGProperty,
+                                     odd: bool)
+                                     -> Result<BigNum, ErrorStack> {
+        unsafe {
+            with_bn_in_ctx!(r, ctx, {
+                ffi::BN_pseudo_rand(r.as_ptr(), bits as c_int, prop as c_int, odd as c_int) == 1
+            })
+        }
+    }
+}
+
+impl Drop for BigNum {
+    fn drop(&mut self) {
+        unsafe { ffi::BN_clear_free(self.as_ptr()); }
+    }
+}
+
+impl Deref for BigNum {
+    type Target = BigNumRef<'static>;
+
+    fn deref(&self) -> &BigNumRef<'static> {
+        &self.0
+    }
+}
+
+impl DerefMut for BigNum {
+    fn deref_mut(&mut self) -> &mut BigNumRef<'static> {
+        &mut self.0
+    }
+}
+
+impl AsRef<BigNumRef<'static>> for BigNum {
+    fn as_ref(&self) -> &BigNumRef<'static> {
+        self.deref()
+    }
+}
+
+impl<'a> fmt::Debug for BigNumRef<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.to_dec_str())
+    }
+}
+
+impl fmt::Debug for BigNum {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.to_dec_str())
+    }
+}
+
+impl<'a> fmt::Display for BigNumRef<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.to_dec_str())
+    }
+}
+
+impl fmt::Display for BigNum {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.to_dec_str())
+    }
+}
+
+impl<'a, 'b> PartialEq<BigNumRef<'b>> for BigNumRef<'a> {
+    fn eq(&self, oth: &BigNumRef) -> bool {
+        unsafe { ffi::BN_cmp(self.as_ptr(), oth.as_ptr()) == 0 }
+    }
+}
+
+impl<'a> PartialEq<BigNum> for BigNumRef<'a> {
+    fn eq(&self, oth: &BigNum) -> bool {
+        self.eq(oth.deref())
+    }
+}
+
+impl<'a> Eq for BigNumRef<'a> {}
+
+impl PartialEq for BigNum {
+    fn eq(&self, oth: &BigNum) -> bool {
+        self.deref().eq(oth)
+    }
+}
+
+impl<'a> PartialEq<BigNumRef<'a>> for BigNum {
+    fn eq(&self, oth: &BigNumRef) -> bool {
+        self.deref().eq(oth)
+    }
+}
+
+impl Eq for BigNum {}
+
+impl<'a, 'b> PartialOrd<BigNumRef<'b>> for BigNumRef<'a> {
+    fn partial_cmp(&self, oth: &BigNumRef) -> Option<Ordering> {
+        Some(self.cmp(oth))
+    }
+}
+
+impl<'a> PartialOrd<BigNum> for BigNumRef<'a> {
+    fn partial_cmp(&self, oth: &BigNum) -> Option<Ordering> {
+        Some(self.cmp(oth.deref()))
+    }
+}
+
+impl<'a> Ord for BigNumRef<'a> {
+    fn cmp(&self, oth: &BigNumRef) -> Ordering {
+        unsafe { ffi::BN_cmp(self.as_ptr(), oth.as_ptr()).cmp(&0) }
+    }
+}
+
+impl PartialOrd for BigNum {
+    fn partial_cmp(&self, oth: &BigNum) -> Option<Ordering> {
+        self.deref().partial_cmp(oth.deref())
+    }
+}
+
+impl<'a> PartialOrd<BigNumRef<'a>> for BigNum {
+    fn partial_cmp(&self, oth: &BigNumRef) -> Option<Ordering> {
+        self.deref().partial_cmp(oth)
+    }
+}
+
+impl Ord for BigNum {
+    fn cmp(&self, oth: &BigNum) -> Ordering {
+        self.deref().cmp(oth.deref())
+    }
+}
+
+impl<'a, 'b> Add<&'b BigNumRef<'b>> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn add(self, oth: &BigNumRef) -> BigNum {
+        self.checked_add(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Sub<&'b BigNumRef<'b>> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn sub(self, oth: &BigNumRef) -> BigNum {
+        self.checked_sub(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Sub<&'b BigNum> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn sub(self, oth: &BigNum) -> BigNum {
+        self.checked_sub(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Sub<&'b BigNum> for &'a BigNum {
+    type Output = BigNum;
+
+    fn sub(self, oth: &BigNum) -> BigNum {
+        self.checked_sub(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Sub<&'b BigNumRef<'b>> for &'a BigNum {
+    type Output = BigNum;
+
+    fn sub(self, oth: &BigNumRef) -> BigNum {
+        self.checked_sub(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Mul<&'b BigNumRef<'b>> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn mul(self, oth: &BigNumRef) -> BigNum {
+        self.checked_mul(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Mul<&'b BigNum> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn mul(self, oth: &BigNum) -> BigNum {
+        self.checked_mul(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Mul<&'b BigNum> for &'a BigNum {
+    type Output = BigNum;
+
+    fn mul(self, oth: &BigNum) -> BigNum {
+        self.checked_mul(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Mul<&'b BigNumRef<'b>> for &'a BigNum {
+    type Output = BigNum;
+
+    fn mul(self, oth: &BigNumRef) -> BigNum {
+        self.checked_mul(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Div<&'b BigNumRef<'b>> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn div(self, oth: &'b BigNumRef<'b>) -> BigNum {
+        self.checked_div(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Div<&'b BigNum> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn div(self, oth: &'b BigNum) -> BigNum {
+        self.checked_div(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Div<&'b BigNum> for &'a BigNum {
+    type Output = BigNum;
+
+    fn div(self, oth: &'b BigNum) -> BigNum {
+        self.checked_div(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Div<&'b BigNumRef<'b>> for &'a BigNum {
+    type Output = BigNum;
+
+    fn div(self, oth: &'b BigNumRef<'b>) -> BigNum {
+        self.checked_div(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Rem<&'b BigNumRef<'b>> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn rem(self, oth: &'b BigNumRef<'b>) -> BigNum {
+        self.checked_mod(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Rem<&'b BigNum> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn rem(self, oth: &'b BigNum) -> BigNum {
+        self.checked_mod(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Rem<&'b BigNumRef<'b>> for &'a BigNum {
+    type Output = BigNum;
+
+    fn rem(self, oth: &'b BigNumRef<'b>) -> BigNum {
+        self.checked_mod(oth).unwrap()
+    }
+}
+
+impl<'a, 'b> Rem<&'b BigNum> for &'a BigNum {
+    type Output = BigNum;
+
+    fn rem(self, oth: &'b BigNum) -> BigNum {
+        self.checked_mod(oth).unwrap()
+    }
+}
+
+impl<'a> Shl<i32> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn shl(self, n: i32) -> BigNum {
+        self.checked_shl(&n).unwrap()
+    }
+}
+
+impl<'a> Shl<i32> for &'a BigNum {
+    type Output = BigNum;
+
+    fn shl(self, n: i32) -> BigNum {
+        self.checked_shl(&n).unwrap()
+    }
+}
+
+impl<'a> Shr<i32> for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn shr(self, n: i32) -> BigNum {
+        self.checked_shr(&n).unwrap()
+    }
+}
+
+impl<'a> Shr<i32> for &'a BigNum {
+    type Output = BigNum;
+
+    fn shr(self, n: i32) -> BigNum {
+        self.checked_shr(&n).unwrap()
+    }
+}
+
+impl<'a> Neg for &'a BigNumRef<'a> {
+    type Output = BigNum;
+
+    fn neg(self) -> BigNum {
+        let mut n = self.to_owned().unwrap();
+        n.negate();
+        n
+    }
+}
+
+impl<'a> Neg for &'a BigNum {
+    type Output = BigNum;
+
+    fn neg(self) -> BigNum {
+        let mut n = self.deref().to_owned().unwrap();
+        n.negate();
+        n
+    }
+}
+
+impl Neg for BigNum {
+    type Output = BigNum;
+
+    fn neg(mut self) -> BigNum {
+        self.negate();
+        self
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use bn::{BnCtx, BigNum};
+
+    #[test]
+    fn test_to_from_slice() {
+        let v0 = BigNum::new_from(10203004).unwrap();
+        let vec = v0.to_vec();
+        let v1 = BigNum::new_from_slice(&vec).unwrap();
+
+        assert!(v0 == v1);
+    }
+
+    #[test]
+    fn test_negation() {
+        let a = BigNum::new_from(909829283).unwrap();
+
+        assert!(!a.is_negative());
+        assert!((-a).is_negative());
+    }
+
+
+    #[test]
+    fn test_prime_numbers() {
+        let a = BigNum::new_from(19029017).unwrap();
+        let p = BigNum::checked_generate_prime(128, true, None, Some(&a)).unwrap();
+
+        let mut ctx = BnCtx::new().unwrap();
+        assert!(ctx.is_prime(&p, 100).unwrap());
+        assert!(ctx.is_prime_fasttest(&p, 100, true).unwrap());
+    }
+}