protected override ValidationResult IsValid(object value, ValidationContext context)
{
// The initial counter can be any value within the limits given by the version.
// DJB version: 64-bit
// IETF version: 32-bit
ChaCha chacha = context.ObjectInstance as ChaCha;
Version currentVersion = ((ChaChaSettings)chacha.Settings).Version;
ulong maxCounter = currentVersion.CounterBits == 32 ? uint.MaxValue : ulong.MaxValue;
BigInteger initialCounter = (BigInteger)value;
return(initialCounter <= maxCounter ?
ValidationResult.Success :
new ValidationResult(ErrorMessage));
}
protected override ValidationResult IsValid(object value, ValidationContext context)
{
// The initialization vector must be of the size specified by the version.
// DJB version: 64-bit
// IETF version: 96-bit
// For the same reasons as with the key, we will do no padding,
// so the IV must be already in the correct size.
ChaCha chacha = context.ObjectInstance as ChaCha;
Version currentVersion = ((ChaChaSettings)chacha.Settings).Version;
byte[] inputIV = value as byte[];
string hexIV = string.Join("", inputIV.Select(b => b.ToString("X2")));
int maxBits = (int)currentVersion.IVBits;
int maxBytes = maxBits / 8;
var required = new StringLengthAttribute(maxBytes * 2)
{
MinimumLength = maxBytes * 2
};
return(required.IsValid(hexIV) ?
ValidationResult.Success :
new ValidationResult(ErrorMessage));
}