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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
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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 ## 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 ### Copying functions
As discussed above, it is simpler to use a single unified API for copying. Therefore, we create the following 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. 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 ### Validation of copying
As discussed above, the best strategy for validation of copies appears to be validation by memory poisoning. As discussed above, the best strategy for validation of copies appears to be validation by memory poisoning.