uplink mobile: add passphrase generation helpers (#2428)

Change-Id: I59229e5221c42919473bc4e14de7e6d186d3832c

mobile/encryption.go

@@ -29,6 +29,12 @@ func (e *EncryptionAccess) SetDefaultKey(keyData []byte) error {
 	return nil
 }
 
+// Serialize returns a base58-serialized encryption access for use with later
+// parsing.
+func (e *EncryptionAccess) Serialize() (b58data string, err error) {
+	return e.lib.Serialize()
+}
+
 // ParseEncryptionAccess parses the base58 encoded encryption context data and
 // returns the resulting context.
 func ParseEncryptionAccess(b58data string) (*EncryptionAccess, error) {

mobile/uplink.go

@@ -172,3 +172,15 @@ func safeError(err error) error {
 	}
 	return fmt.Errorf("%v", err.Error())
 }
+
+// SaltedKeyFromPassphrase returns a key generated from the given passphrase using a stable,
+// project-specific salt
+func (project *Project) SaltedKeyFromPassphrase(passphrase string) (keyData []byte, err error) {
+	scope := project.scope.child()
+
+	key, err := project.lib.SaltedKeyFromPassphrase(scope.ctx, passphrase)
+	if err != nil {
+		return nil, err
+	}
+	return key[:], nil
+}