TheAlgorithms/C-Sharp · error · ArgumentException

Not enough space in input array for padding

Error message

Not enough space in input array for padding

What it means

TbcPadding.AddPadding checks that the input array can hold at least the existing data (input.Length - inputOffset must be >= 0). A negative count means inputOffset exceeds the array length, so the method throws ArgumentException instead of reading or writing out of bounds.

Solutions

1. Ensure inputOffset is within [0, input.Length].
2. Recompute the offset from the array actually passed.
3. Verify you're not passing an empty array while advancing offsets across chunks.
4. Clamp or validate offsets at the API boundary.

Example fix

// before
padding.AddPadding(chunk, chunk.Length + 1, ...); // offset past end
// after
if (offset > chunk.Length) throw new InvalidOperationException("bad offset");
padding.AddPadding(chunk, offset, ...);

if (input is null || inputOffset < 0 || inputOffset > input.Length)
    throw new ArgumentException("inputOffset must be within [0, input.Length]");

static bool IsValidOffset(byte[] buf, int offset) => buf is not null && offset >= 0 && offset <= buf.Length;

try { padding.AddPadding(input, offset, len); }
catch (ArgumentException) { /* log offset bookkeeping bug with buffer + offset values */ throw; }

When it happens

Trigger: Calling AddPadding(input, offset, ...) where inputOffset > input.Length — e.g. offset pointing past a fully populated array, or passing an empty array with a non-zero offset.

Common situations: Off-by-one in offset bookkeeping across chunked writes; passing the wrong array (empty) with an offset computed for the original; reusing offsets from a previous buffer size.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Not enough space in input array for padding
• Invalid block size
• Input length must be a multiple of block size
• Invalid padding length
• Invalid padding

AI-assisted analysis of TheAlgorithms/C-Sharp@96e2905cab (2026-09-13). Data as JSON: /api/errors/02136900b6983288. Report an issue: GitHub.

Appendix: source

Thrown at Algorithms/Crypto/Paddings/TbcPadding.cs:34

public class TbcPadding : IBlockCipherPadding
{
    /// <summary>
    /// Adds padding to the input array according to the TBC standard.
    /// </summary>
    /// <param name="input">The input array to be padded.</param>
    /// <param name="inputOffset">The offset in the input array where the padding starts.</param>
    /// <returns>The number of bytes that were added.</returns>
    /// <exception cref="ArgumentException">Thrown when the input array does not have enough space for padding.</exception>
    public int AddPadding(byte[] input, int inputOffset)
    {
        // Calculate the number of bytes to be padded.
        var count = input.Length - inputOffset;
        byte code;

        // Check if the input array has enough space for padding.
        if (count < 0)
        {
            throw new ArgumentException("Not enough space in input array for padding");
        }

        if (inputOffset > 0)
        {
            // Get the last bit of the previous byte.
            var lastBit = input[inputOffset - 1] & 0x01;

            // Set the padding code to 0xFF if the last bit is 0, or 0x00 if the last bit is 1.
            code = (byte)(lastBit == 0 ? 0xff : 0x00);
        }
        else
        {
            // Get the last bit of the last byte in the input array.
            var lastBit = input[^1] & 0x01;

            // Set the padding code to 0xff if the last bit is 0, or 0x00 if the last bit is 1.
            code = (byte)(lastBit == 0 ? 0xff : 0x00);
        }

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