iPhone JPG图像具有非标准魔术字节ff d8 ff e1? [英] iPhone JPG image has non-standard magic bytes ff d8 ff e1?

问题描述

我的Web应用程序在接受上传的图像之前，先检查文件扩展名的前四个字节.一位同事向我展示了他iPhone上的图像，这些图像被拒绝了.它们具有不同的第四字节(e1 = 225，而不是预期的e0 = 224).

My web app checks the first four bytes against the file extension before accepting uploaded images. A coworker showed me images from his iPhone which are being rejected. These have a different fourth byte (e1 = 225 instead of the expected e0 = 224).

这在iPhone上很常见吗? JPG文件中还有其他可能使用的魔术字节字符串吗?

Is this usual for iPhones? Are there other possible magic byte strings used in JPG files?

找到了这个有用的列表: http://www.garykessler.net/library/file_sigs.html

found this useful list: http://www.garykessler.net/library/file_sigs.html

推荐答案

它们似乎以某种方式指示JPEG的子类别.我发现，FF D8 FF E0魔术表示"JFIF JPEG"，而FF D8 FF E1魔术表示"EXIF JPEG".

They seem to indicate a sub category of JPEG in some way. What I have found out is that the FF D8 FF E0 magic indicates a "JFIF JPEG" whereas the FF D8 FF E1 indicates an "EXIF JPEG".

编辑:在Google缓存中找到了此文件: http://tinyurl.com/ydtjpjw (有趣的是，它表明三星还有更多变体)

Edit: Found this one in a google cache: http://tinyurl.com/ydtjpjw (interesting because it indicates that Samsung has a few more variations)

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