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move bignumber random and umod to util package big.go
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,63 @@ | ||
| package util | ||
|
|
||
| import ( | ||
| "crypto/rand" | ||
| "math/big" | ||
| ) | ||
|
|
||
| // Umod returns the unsigned modulus of x and y. | ||
| // It ensures the result is always non-negative. | ||
| func Umod(x *big.Int, y *big.Int) *big.Int { | ||
| // Ensure divisor y is not zero | ||
| if y.Sign() == 0 { | ||
| panic("division by zero") | ||
| } | ||
|
|
||
| // If the dividend x is zero, the modulus is zero | ||
| if x.Sign() == 0 { | ||
| return big.NewInt(0) | ||
| } | ||
|
|
||
| mod := new(big.Int) | ||
|
|
||
| // Handle cases where x is negative and y is positive | ||
| if x.Sign() < 0 && y.Sign() > 0 { | ||
| mod.Neg(x) | ||
| mod.Mod(mod, y) | ||
| mod.Neg(mod) | ||
| if mod.Sign() < 0 { | ||
| mod.Add(mod, y) | ||
| } | ||
| } else if x.Sign() > 0 && y.Sign() < 0 { | ||
| // Handle cases where x is positive and y is negative | ||
| mod.Mod(x, new(big.Int).Neg(y)) | ||
| } else if x.Sign() < 0 && y.Sign() < 0 { | ||
| // Handle cases where both x and y are negative | ||
| mod.Neg(x) | ||
| mod.Mod(mod, new(big.Int).Neg(y)) | ||
| mod.Neg(mod) | ||
| if mod.Sign() < 0 { | ||
| mod.Sub(mod, y) | ||
| } | ||
| } else { | ||
| // Both numbers are positive | ||
| mod.Mod(x, y) | ||
| } | ||
|
|
||
| // Ensure the result is non-negative | ||
| if mod.Sign() < 0 { | ||
| mod.Add(mod, new(big.Int).Abs(y)) | ||
| } | ||
|
|
||
| return mod | ||
| } | ||
|
|
||
| func NewRandomBigInt(byteLen int) *big.Int { | ||
| b := make([]byte, byteLen) | ||
| _, err := rand.Read(b) | ||
| if err != nil { | ||
| panic(err) | ||
| } | ||
|
|
||
| return new(big.Int).SetBytes(b) | ||
| } |