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Move implementation by module table earlier

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Signed-off-by: David Horstmann <david.horstmann@arm.com>
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David Horstmann 2023-10-19 15:14:20 +01:00
parent dae0ad439f
commit 3f7e42a750
1 changed files with 14 additions and 14 deletions
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docs/architecture/psa-shared-memory.md
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@ -420,6 +420,20 @@ Make sure that such mechanisms preserve the guarantees when buffers overlap.
## Detailed design
### Implementation by module
Module | Input protection strategy | Output protection strategy | Notes
---|---|---|---
Hash and MAC | Careful access | Careful access | Low risk of multiple-access as the input and output are raw unformatted data.
Cipher | Copying | Copying |
AEAD | Copying (careful access for additional data) | Copying |
Key derivation | Careful access | Careful access |
Asymmetric signature | Careful access | Copying | Inputs to signatures are passed to a hash. This will no longer hold once PureEdDSA support is implemented.
Asymmetric encryption | Copying | Copying |
Key agreement | Copying | Copying |
PAKE | Copying | Copying |
Key import / export | Copying | Copying | Keys may be imported and exported in DER format, which is a structured format and therefore susceptible to read-read inconsistencies and potentially write-read inconsistencies.
### Copying functions
As discussed above, it is simpler to use a single unified API for copying. Therefore, we create the following functions:
@ -443,20 +457,6 @@ This function would first copy the `buffers->out` buffer to the user-supplied ou
Some PSA functions may not use these convenience functions as they may have local optimizations that reduce memory usage. For example, ciphers may be able to use a single intermediate buffer for both input and output.
### Implementation by module
Module | Input protection strategy | Output protection strategy | Notes
---|---|---|---
Hash and MAC | Careful access | Careful access | Low risk of multiple-access as the input and output are raw unformatted data.
Cipher | Copying | Copying |
AEAD | Copying (careful access for additional data) | Copying |
Key derivation | Careful access | Careful access |
Asymmetric signature | Careful access | Copying | Inputs to signatures are passed to a hash. This will no longer hold once PureEdDSA support is implemented.
Asymmetric encryption | Copying | Copying |
Key agreement | Copying | Copying |
PAKE | Copying | Copying |
Key import / export | Copying | Copying | Keys may be imported and exported in DER format, which is a structured format and therefore susceptible to read-read inconsistencies and potentially write-read inconsistencies.
### Validation of copying
As discussed above, the best strategy for validation of copies appears to be validation by memory poisoning.