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27 lines
847 B
Go
27 lines
847 B
Go
package s2k
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// Cache stores keys derived with s2k functions from one passphrase
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// to avoid recomputation if multiple items are encrypted with
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// the same parameters.
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type Cache map[Params][]byte
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// GetOrComputeDerivedKey tries to retrieve the key
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// for the given s2k parameters from the cache.
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// If there is no hit, it derives the key with the s2k function from the passphrase,
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// updates the cache, and returns the key.
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func (c *Cache) GetOrComputeDerivedKey(passphrase []byte, params *Params, expectedKeySize int) ([]byte, error) {
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key, found := (*c)[*params]
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if !found || len(key) != expectedKeySize {
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var err error
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derivedKey := make([]byte, expectedKeySize)
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s2k, err := params.Function()
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if err != nil {
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return nil, err
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}
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s2k(derivedKey, passphrase)
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(*c)[*params] = key
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return derivedKey, nil
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}
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return key, nil
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}
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