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Difference between revisions of "S5L8720 (Hardware - SHA1)"
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===Programming Guide=== |
===Programming Guide=== |
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| − | As |
+ | As there is no real documentation of the hardware (The Samsung S3C6400X seams to use a very similar SHA-1 generator, but not the same), this is based on what [[iBoot]] does and on a lot of trial-and-error. |
====How it works==== |
====How it works==== |
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Basically it is like a hardware version of a SHA-1 algorithm. The hardware processes data in 512Bit (64 Bytes) chunks (Just like a software algorithm). <br> |
Basically it is like a hardware version of a SHA-1 algorithm. The hardware processes data in 512Bit (64 Bytes) chunks (Just like a software algorithm). <br> |
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====Calculating the SHA-1 of a message==== |
====Calculating the SHA-1 of a message==== |
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| − | # Prepare the message as usual. See [ |
+ | # Prepare the message as usual. See [[wikipedia:Secure Hash Algorithm|Wikipedia on SHA]] |
# Switch on the clock for the SHA-1 generator |
# Switch on the clock for the SHA-1 generator |
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# Reset the generator. To do this set bit 0 of reset register and clear it afterwards (iBoot waits until the hash is ready before resetting it) |
# Reset the generator. To do this set bit 0 of reset register and clear it afterwards (iBoot waits until the hash is ready before resetting it) |
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# Read the calculated hash of the Output SHA-1 Hash registers |
# Read the calculated hash of the Output SHA-1 Hash registers |
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# Switch off the clock |
# Switch off the clock |
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| − | |||
==Registers== |
==Registers== |
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Latest revision as of 05:12, 29 July 2010
Contents
S5L8720 SHA-1 Hardware
Base Address: 0x38000000
Programming Guide
As there is no real documentation of the hardware (The Samsung S3C6400X seams to use a very similar SHA-1 generator, but not the same), this is based on what iBoot does and on a lot of trial-and-error.
How it works
Basically it is like a hardware version of a SHA-1 algorithm. The hardware processes data in 512Bit (64 Bytes) chunks (Just like a software algorithm).
It does NO pre-processing (appending a '1' Bit to the data, pad the data so that the length mod 512 is 448, and append the bit-length of the data as a 64-bit big-endian integer).
This has to be done in software.
Calculating the SHA-1 of a message
- Prepare the message as usual. See Wikipedia on SHA
- Switch on the clock for the SHA-1 generator
- Reset the generator. To do this set bit 0 of reset register and clear it afterwards (iBoot waits until the hash is ready before resetting it)
- Clear (Write 0) to the Configuration Register (Not sure if this is needed as it already reads 0 after resetting, but iBoot does it)
- Clear register 0x80 and 0x10 (Also not sure why, as they also read 0)
- Write 64 bytes of the message to the data input registers starting at the lowest
- If this were the the first 64 bytes clear bit 3 in the Configuration register, else set it
- Set bit 1 (Start Hash) of the Configuration register and wait until bit 0 (Hash Busy) is cleared
- If more data to hash go to point 6
- Read the calculated hash of the Output SHA-1 Hash registers
- Switch off the clock
Registers
Register Summary
| Register | Description |
| 0x00 | Configuration |
| 0x04 | Reset |
| 0x08 | Unknown, but referenced in iBoot |
| 0x0C | Unknown, but referenced in iBoot |
| 0x10 | Unknown, but referenced in iBoot (Set to 0 before calculating a hash) |
| 0x20 - 0x30 | Output SHA-1 hash / Input Initialization Vector |
| 0x40 - 0x7C | Data Input (64 Bytes) |
| 0x80 | Unknown, but referenced in iBoot (Set to 0 before calculating a hash) |
| 0x84 | Unknown, but referenced in iBoot |
| 0x8C | Unknown, but referenced in iBoot |
Configuration Register
| Bit | Function |
| Bit 0 | Hash Busy. Is set when the hash calculation is started and cleared when the generator is done. |
| Bit 1 | Start Hash. Set to 1 to start hashing of the data in the Input Data registers. |
| Bit 2 | Unknown |
| Bit 3 | Config IV. Use arbitary IV (=1), Use SHA-1 constants (=0) (Used for starting a new hash (=0), or continue a previous one (=1)). |
All other bits are unknown or not used
Reset Register
| Bit | Function |
| Bit 0 | Reset Hash. Resets the generator and all registers. |
All other bits are unknown or not used
Hash Out / IV In
Read: Outputs the hash in little-endian
Write: Set the initialization vectors
Data Input
Read: Read what was previously written there (like normal RAM)
Write: The current 64 byte data chunk to calculate the hash of. (little-endian)
