This article aims to present, adapt, and propose the use of the Balanced Scorecard (BSC) as a tool to support strategic management for sustainable cities. To achieve this goal, publications and 27 sustainable cities projects were also consulted, through project reports and programs from the cities themselves on the topic were consulted. A text mining analysis was applied to the results obtained in this literature review to find the main factors related to sustainable cities. To evaluate the findings of this first stage, consultations with specialists were carried out, specifically to assess the main factors. Based on the previous steps, and based on the original BSC, an adaptation of the tool was proposed, where its structure was changed to meet the needs of the strategic management of sustainable cities. It was concluded that creating a sustainable city requires understanding the difficulties faced by urban center managers with the implementation and management of institutional sustainable development practices. The BSC for sustainable cities can assist as a viable management strategic tool to more efficient use of resources in order to develop sustainable cities.

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In a sanitizable signature scheme the signer allows a designated third party, called the sanitizer, to modify certain parts of the message and adapt the signature accordingly. Ateniese et al. (ESORICS 2005) introduced this primitive and proposed five security properties which were formalized by Brzuska et al. (PKC 2009). Subsequently, Brzuska et al. (PKC 2010 suggested an additional security notion, called unlinkability which says that one cannot link sanitized message-signature pairs of the same document. Moreover, the authors gave a generic construction based on group signatures that have a certain structure. However, the special structure required from the group signature scheme only allows for inefficient instantiations. Here, we present the first efficient instantiation of unlinkable sanitizable signatures. Our construction is based on a novel type of signature schemes with re-randomizable keys. Intuitively, this property allows to re-randomize both the signing and the verification key separately but consistently. This allows us to sign the message with a re-randomized key and to prove in zero-knowledge that the derived key originates from either the signer or the sanitizer. We instantiate this generic idea with Schnorr signatures and efficient Σ-protocols, which we convert into non-interactive zero-knowledge proofs via the Fiat-Shamir transformation. Our construction is at least one order of magnitude faster than instantiating the generic scheme of Brzuska et al. with the most efficient group signature schemes. Definition of Sanitizable SignaturesThe following definition of sanitizable signature schemes is taken in verbatim from [BFF + 09, BFLS10]. Definition 1 (Sanitizable Signature Scheme).A sanitizable signature scheme SanS = (KGen sig , KGen san , Sign, Sanit, Verify, Proof, Judge) consists of seven algorithms:Key Generation. There are two key generation algorithms, one for the signer and one for the sanitizer. Both create a pair of keys, a private and the corresponding public key:and (sk san , pk san ) ← KGen san (1 κ ).Signing. The signing algorithm takes as input a message m ∈ {0, 1} * , a signer secret key sk sig , a sanitizer public key pk san , as well as a description Adm of the admissible modifications to m by the sanitizer and outputs a signature σ. We assume that Adm can be recovered from any signature:σ ← Sign(m, sk sig , pk san , Adm).Sanitizing. The sanitizing algorithm takes as input a message m ∈ {0, 1} * , a description Mod of the desired modifications to m, a signature σ, the signer's public key pk sig , and a sanitizer secret key sk san . It modifies the message m according to the modification instruction Mod and outputs a new signature σ for the modified message m = Mod(m) or possibly ⊥ in case of an error:{(m , σ ), ⊥} ← Sanit(m, Mod, σ, pk sig , sk san ).Verification. The verification algorithm takes as input a message m, a candidate signature σ, a signer public key pk sig , as well as a sanitizer public key pk san and outputs a bit b:b ← Verify(m, σ, pk sig , pk san ).Proof. The p...