GetPaddingLength() [3/3]

int Internal.Cryptography.UniversalCryptoDecryptor.GetPaddingLength ( ReadOnlySpan< byte > block )

inlineprivate

Definition at line 156 of file UniversalCryptoDecryptor.cs.

    {
        int num = 0;
        switch (base.PaddingMode)
        {
        case PaddingMode.ANSIX923:
        {
            num = block[^1];
            if (num <= 0 || num > base.InputBlockSize)
            {
                throw new CryptographicException(System.SR.Cryptography_InvalidPadding);
            }
            for (int j = block.Length - num; j < block.Length - 1; j++)
            {
                if (block[j] != 0)
                {
                    throw new CryptographicException(System.SR.Cryptography_InvalidPadding);
                }
            }
            break;
        }
        case PaddingMode.ISO10126:
            num = block[^1];
            if (num <= 0 || num > base.InputBlockSize)
            {
                throw new CryptographicException(System.SR.Cryptography_InvalidPadding);
            }
            break;
        case PaddingMode.PKCS7:
        {
            num = block[^1];
            if (num <= 0 || num > base.InputBlockSize)
            {
                throw new CryptographicException(System.SR.Cryptography_InvalidPadding);
            }
            for (int i = block.Length - num; i < block.Length - 1; i++)
            {
                if (block[i] != num)
                {
                    throw new CryptographicException(System.SR.Cryptography_InvalidPadding);
                }
            }
            break;
        }
        case PaddingMode.None:
        case PaddingMode.Zeros:
            num = 0;
            break;
        default:
            throw new CryptographicException(System.SR.Cryptography_UnknownPaddingMode);
        }
        return block.Length - num;
    }

References System.SR.Cryptography_InvalidPadding, System.SR.Cryptography_UnknownPaddingMode, and System.ReadOnlySpan< T >.Length.