View source for /dev/sha

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'''/dev/sha''' is an IPC interface for the [[Hardware/SHA-1 engine | SHA-1 engine]] that accepts IOS_Open, IOS_Close & IOCTLV commands.

Internally in IOS, it uses 2 FDs: one of 0x10001 normally calculating SHA-1 hashes and 0x10002 when dealing with HMAC key hashes (also based on SHA). Despite this, it is better to do an IOS_Open when using this resource.

/dev/sha handles both SHA-1 hashing and HMAC verification in modular IOS versions (IOS28 and later). For monolithic IOS versions (IOS22 and earlier), HMAC verification is done in a dedicated separate device called [[:/dev/hmac]].