public void TestCombine_invalid()
{
// Not enough parts
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Combine(null));
// Mis-match in length
var parts = new byte[][]
{
Encoding.UTF8.GetBytes("foo"),
Encoding.UTF8.GetBytes("ba"),
};
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Combine(parts));
//Too short
parts = new byte[][]
{
Encoding.UTF8.GetBytes("f"),
Encoding.UTF8.GetBytes("b"),
};
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Combine(parts));
parts = new byte[][]
{
Encoding.UTF8.GetBytes("foo"),
Encoding.UTF8.GetBytes("foo"),
};
Assert.ThrowsAny <InvalidOperationException>(
() => HashiCorpShamir.Combine(parts));
}
public override byte[] Split(byte[] secretClear, int shareCount, int threshold)
{
Shares = HashiCorpShamir.Split(secretClear, shareCount, threshold);
// All encoded data is contained within the encoded shares,
// so there is no transformed form of the secret to return
return(new byte[0]);
}
public void TestField_Divide()
{
Assert.Equal(0, HashiCorpShamir.Div(0, 7));
Assert.Equal(1, HashiCorpShamir.Div(3, 3));
Assert.Equal(2, HashiCorpShamir.Div(6, 3));
}
public void TestField_Mult()
{
Assert.Equal(9, HashiCorpShamir.Mult(3, 7));
Assert.Equal(0, HashiCorpShamir.Mult(3, 0));
Assert.Equal(0, HashiCorpShamir.Mult(0, 3));
}
public void TestSplit()
{
var secret = Encoding.UTF8.GetBytes("test");
var ret = HashiCorpShamir.Split(secret, 5, 3);
Assert.Equal(5, ret.Length);
foreach (var share in ret)
{
Assert.Equal(share.Length, secret.Length + 1);
}
}
public void TestInterpolate_Rand()
{
for (int i = 0; i < 256; i++)
{
var p = HashiCorpShamir.MakePolynomial((byte)i, 2);
var x_vals = new byte[] { 1, 2, 3 };
var y_vals = new byte[] { p.Evaluate(1), p.Evaluate(2), p.Evaluate(3) };
// out := interpolatePolynomial(x_vals, y_vals, 0)
// if out != uint8(i) {
// t.Fatalf("Bad: %v %d", out, i)
// }
Assert.Equal((byte)i,
HashiCorpShamir.InterpolatePolynomial(x_vals, y_vals, 0));
}
}
public void TestPolynomial_Eval()
{
var p = HashiCorpShamir.MakePolynomial(42, 1);
Assert.Equal(42, p.Evaluate(0));
// out := p.evaluate(1)
// exp := add(42, mult(1, p.coefficients[1]))
// if out != exp {
// t.Fatalf("bad: %v %v %v", out, exp, p.coefficients)
// }
var ret = p.Evaluate(1);
var exp = HashiCorpShamir.Add(42,
HashiCorpShamir.Mult(1, p.Coefficients[1]));
Assert.Equal(ret, exp);
}
public void TestSplit_invalid()
{
var secret = Encoding.UTF8.GetBytes("test");
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Split(secret, 0, 0));
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Split(secret, 2, 3));
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Split(secret, 1000, 3));
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Split(secret, 10, 1));
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Split(new byte[0], 3, 2));
Assert.ThrowsAny <ArgumentException>(
() => HashiCorpShamir.Split(null, 3, 2));
// if _, err := Split(secret, 0, 0); err == nil {
// t.Fatalf("expect error")
// }
// if _, err := Split(secret, 2, 3); err == nil {
// t.Fatalf("expect error")
// }
// if _, err := Split(secret, 1000, 3); err == nil {
// t.Fatalf("expect error")
// }
// if _, err := Split(secret, 10, 1); err == nil {
// t.Fatalf("expect error")
// }
// if _, err := Split(nil, 3, 2); err == nil {
// t.Fatalf("expect error")
// }
}
public void TestCombine()
{
var secret = Encoding.UTF8.GetBytes("test");
var ret = HashiCorpShamir.Split(secret, 5, 3);
// There is 5*4*3 possible choices,
// we will just brute force try them all
for (int i = 0; i < 5; i++)
{
for (var j = 0; j < 5; j++)
{
if (j == i)
{
continue;
}
for (var k = 0; k < 5; k++)
{
if (k == i || k == j)
{
continue;
}
var parts = new byte[][] { ret[i], ret[j], ret[k] };
var recomb = HashiCorpShamir.Combine(parts);
Assert.Equal(recomb, secret);
// if !bytes.Equal(recomb, secret) {
// t.Errorf("parts: (i:%d, j:%d, k:%d) %v", i, j, k, parts)
// t.Fatalf("bad: %v %v", recomb, secret)
// }
}
}
}
}
public override byte[] Combine(byte[] secretCrypt)
{
return(HashiCorpShamir.Combine(Shares.ToArray()));
}
// Combine is used to reverse a Split and reconstruct a secret
// once a `threshold` number of parts are available.
public static byte[] Combine(byte[][] parts)
{
// Verify enough parts provided
if ((parts?.Length).GetValueOrDefault() < 2)
{
throw new ArgumentOutOfRangeException(nameof(parts),
"less than two parts cannot be used to reconstruct the secret");
}
// Verify the parts are all the same length
var firstPartLen = parts[0].Length;
if (firstPartLen < 2)
{
throw new ArgumentException(nameof(parts),
"parts must be at least two bytes");
}
for (int i = 1; i < parts.Length; i++)
{
if (parts[i].Length != firstPartLen)
{
throw new ArgumentException(nameof(parts),
"all parts must be the same length");
}
}
// Create a buffer to store the reconstructed secret
var secret = new byte[firstPartLen - 1];
// Buffer to store the samples
var x_samples = new byte[parts.Length];
var y_samples = new byte[parts.Length];
// Set the x value for each sample and ensure no x_sample values are the same,
// otherwise div() can be unhappy
var checkMap = new Dictionary <byte, bool>();
for (int i = 0; i < parts.Length; i++)
{
var part = parts[i];
var samp = part[firstPartLen - 1];
if (checkMap.ContainsKey(samp))
{
throw new InvalidOperationException("duplicate part detected");
}
checkMap[samp] = true;
x_samples[i] = samp;
}
// Reconstruct each byte
for (int idx = 0; idx < secret.Length; idx++)
{
// Set the y value for each sample
for (int i = 0; i < parts.Length; i++)
{
var part = parts[i];
y_samples[i] = part[idx];
}
// Interpolte the polynomial and compute the value at 0
var val = HashiCorpShamir.InterpolatePolynomial(x_samples, y_samples, 0);
// Evaluate the 0th value to get the intercept
secret[idx] = val;
}
return(secret);
}
public void TestPolynomial_Random()
{
var p = HashiCorpShamir.MakePolynomial(42, 2);
Assert.Equal(42, p.Coefficients[0]);
}
public void TestField_Add()
{
Assert.Equal(0, HashiCorpShamir.Add(16, 16));
Assert.Equal(7, HashiCorpShamir.Add(3, 4));
}