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<xml><records><record><source-app name="Bibcite" version="8.x">Drupal-Bibcite</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Osmanbey Uzunkol</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Comments on “verifiable outsourced attribute-based signature scheme”</style></title></titles><keywords/><dates><year><style face="normal" font="default" size="100%">2019</style></year><pub-dates><date><style face="normal" font="default" size="100%">2019/05/01</style></date></pub-dates></dates><secondary-title><style face="normal" font="default" size="100%">Multimedia Tools and Applications </style></secondary-title><urls><style face="normal" font="default" size="100%">https://doi.org/10.1007/s11042-018-6725-7</style></urls><electronic-resource-num><style face="normal" font="default" size="100%">10.1007/s11042-018-6725-7</style></electronic-resource-num><pages><style face="normal" font="default" size="100%">11735-11742, </style></pages><volume><style face="normal" font="default" size="100%">78</style></volume><abstract><style face="normal" font="default" size="100%">Ren and Jiang recently published a “verifiable outsourced attribute-based signature scheme” in Multimedia Tools and Applications. In this note, we first provide two attacks on the verifiability of the semi-signatures of this scheme by showing that a malicious signing-cloud service provider (S-CSP) can always cheat the signer unlike the authors’ claim. Moreover, one of these attacks also implies that an untrusted S-CSP can always forge signatures contrary to the claimed unforgeability against chosen message attacks. Therefore, this scheme unfortunately does not satisfy the main security properties for a delegated signature scheme.</style></abstract><isbn><style face="normal" font="default" size="100%">1573-7721</style></isbn><issue><style face="normal" font="default" size="100%">9</style></issue></record></records></xml>
