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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Merkle signature scheme ： ウィキペディア英語版 Merkle signature scheme The Merkle signature scheme is a digital signature scheme based on hash trees (also called Merkle trees) and one-time signatures such as the Lamport signature scheme. It was developed by Ralph Merkle in the late 1970s and is an alternative to traditional digital signatures such as the Digital Signature Algorithm or RSA. The advantage of the Merkle Signature Scheme is that it is believed to be resistant against quantum computer algorithms. The traditional public key algorithms, such as RSA and ELGamal would become insecure in case an effective quantum computer can be built (due to Shor's algorithm). The Merkle Signature Scheme however only depends on the existence of secure hash functions. This makes the Merkle Signature Scheme very adjustable and resistant to quantum computing. ==Key generation== The Merkle Signature Scheme can be used to sign a limited number of messages with one public key $pub$. The number of possible messages must be a power of two, so we denote the possible number of messages as $N=2^n$. The first step of generating the public key $pub$ is to generate $N$ public/private key pairs $(X\_i,\; Y\_i)$ of some one-time signature scheme (such as the Lamport signature scheme). For each $1\; \backslash leq\; i\; \backslash leq\; 2^n$, a hash value $h\_i=H(Y\_i)$ is computed. With these hash values $h\_i$ a hash tree is built, by placing these $2^n$ hash values as leaves and recursively hashing to form a binary tree. Let $a\_$ denote the node in the tree with height $i$ and left-right position $j$. Then, the hash values $h\_i=a\_$ are the leaves. The value for each inner node of the tree is the hash of the concatenation of its two children. For example $a\_=H(a\_||a\_)$ and $a\_=H(a\_||a\_)$. In this way, a tree with $2^n$ leaves and $2^-1$ nodes is built. The private key of the Merkle Signature Scheme is the entire set of $(X\_i,\; Y\_i)$ pairs. (One of the major problems with the scheme is that the size of the private key scales with the number of messages to be sent.) The public key $pub$ is the root of the tree, $a\_$. The individual public keys $X\_i$ can be made public without breaking security. However, as they aren't needed in the public key, it's better to keep them secret to minimize its size. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Merkle signature scheme」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.