Source file src/github.com/ProtonMail/go-crypto/openpgp/s2k/s2k_cache.go

Documentation: github.com/ProtonMail/go-crypto/openpgp/s2k

     1  package s2k
     2  
     3  // Cache stores keys derived with s2k functions from one passphrase
     4  // to avoid recomputation if multiple items are encrypted with
     5  // the same parameters.
     6  type Cache map[Params][]byte
     7  
     8  // GetOrComputeDerivedKey tries to retrieve the key 
     9  // for the given s2k parameters from the cache.
    10  // If there is no hit, it derives the key with the s2k function from the passphrase,
    11  // updates the cache, and returns the key.
    12  func (c *Cache) GetOrComputeDerivedKey(passphrase []byte, params *Params, expectedKeySize int) ([]byte, error) {
    13  	key, found := (*c)[*params]
    14  	if !found || len(key) != expectedKeySize {
    15  		var err error
    16  		derivedKey := make([]byte, expectedKeySize)
    17  		s2k, err := params.Function()
    18  		if err != nil {
    19  			return nil, err
    20  		}
    21  		s2k(derivedKey, passphrase)
    22  		(*c)[*params] = key
    23  		return derivedKey, nil
    24  	}
    25  	return key, nil
    26  }
    27  

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