短語詞組短語undeniable digital signature 不可否認(rèn)簽名threshold undeniable signature 門限不可否認(rèn)簽名Undeniable Signature Scheme 不可觝賴簽名方案convertible undeniable signature 可轉(zhuǎn)換不可否認(rèn)簽名certificate -based undeniable signature 基於証書不可否認(rèn)簽名 返回 undeniable signature