public SaltShaker(char minChar, char maxChar, int saltLength, SaltCreationModel creationModel, SaltEmbeddingModel embedModel, int seed)
{
MethodContract.Assert(minChar < maxChar, nameof(minChar) + " must be less than " + nameof(maxChar));
MethodContract.Assert(saltLength > 0, nameof(saltLength));
this.seed = seed;
this.model = creationModel;
this.embed = embedModel;
this.minChar = minChar;
this.maxChar = maxChar;
this.saltLength = saltLength;
}
public static string EmbedSalt(SaltEmbeddingModel model, string payload, string salt)
{
if (!string.IsNullOrEmpty(payload))
{
if (!string.IsNullOrEmpty(salt))
{
if (salt.Length > payload.Length)
{
if (model == SaltEmbeddingModel.Default || model == SaltEmbeddingModel.Randomized)
{
int hash = Math.Abs(payload.GetHashCode()); //calc the entropy
while (hash > salt.Length)
{
hash = hash - salt.Length;
}
//ok, hash is still positive, but now less than salt.length so we can embed
char[] front = payload.ToCharArray();
char[] back = salt.ToCharArray();
if (hash + front.Length < back.Length) //direct embed
{
for (int i = 0; i < front.Length; i++)
{
back[hash + i] = front[i];
}
}
else //need to do a wrap around like a circular array
{
int wrapIndex = back.Length - hash;
for (int i = 0; i < front.Length; i++)
{
if (hash + i < back.Length)
{
back[hash + i] = front[i];
}
else
{
back[i - wrapIndex] = front[i];
}
}
}
return(new string(back));
}
else if (model == SaltEmbeddingModel.Middle) //goes in the middle
{
char[] front = payload.ToCharArray();
char[] back = salt.ToCharArray();
int start = (back.Length - front.Length) / 2;
for (int i = 0; i < front.Length; i++)
{
back[start + i] = front[i];
}
return(new string(back));
}
else if (model == SaltEmbeddingModel.Beginning) //easiest one to do
{
char[] data = salt.ToCharArray();
for (int i = 0; i < payload.Length; i++)
{
data[i] = payload[i];
}
return(new string(data));
}
else //end
{
char[] data = salt.ToCharArray();
int indexBase = data.Length - payload.Length; //first spot to replace
for (int i = 0; i < payload.Length; i++)
{
data[indexBase + i] = payload[i];
}
return(new string(data));
}
}
else if (salt.Length == payload.Length)
{
return(payload); //no extra chars
}
else
{
return(payload.Substring(0, salt.Length)); //truncate to salt length
}
}
return(payload); //nothing to embed in
}
return(salt);
}
