DES 加密密钥
DES Encryption keys
我正在阅读有关 DES 三重加密的内容，我发现了 3 个密钥的很多不同组合，例如：使用 k1 - k2 - k3，因为有 k1- k2 - k1，...
我的问题是，这些组合之间有什么区别？哪个是可取的（最常用的）？
应该为以下答案提供深度：
使用三个不同的键是最好的方法。事实上，这是美国政府（和美国政府承包商）的唯一选择：
3.2.1.2 Triple Data Encryption Algorithm (TDEA)
The Triple Data Encryption Algorithm (TDEA), also known as Triple DES, uses the DES
cryptographic engine to transform data in three operations. TDEA is
specified in SP 800-67.
TDEA encrypts data in blocks of 64 bits, using three keys that define
a key bundle. The use of TDEA using three distinctly different
(i.e., mathematically independent) keys is approved and is
commonly known as three-key TDEA (also referred to as 3TDEA
or 3TDES).
Other variations of TDEA, where two or three of the keys
are identical, are no longer approved for applying cryptographic
protection because of increased computing power or weaknesses in the
algorithm.
（强调我的）。资料来源：http://csrc.nist.gov/publications/drafts/800-175/sp800-175b_draft.pdf
我正在阅读有关 DES 三重加密的内容，我发现了 3 个密钥的很多不同组合，例如：使用 k1 - k2 - k3，因为有 k1- k2 - k1，... 我的问题是，这些组合之间有什么区别？哪个是可取的（最常用的）？
使用三个不同的键是最好的方法。事实上，这是美国政府（和美国政府承包商）的唯一选择：
3.2.1.2 Triple Data Encryption Algorithm (TDEA)
The Triple Data Encryption Algorithm (TDEA), also known as Triple DES, uses the DES cryptographic engine to transform data in three operations. TDEA is specified in SP 800-67.
TDEA encrypts data in blocks of 64 bits, using three keys that define a key bundle. The use of TDEA using three distinctly different (i.e., mathematically independent) keys is approved and is commonly known as three-key TDEA (also referred to as 3TDEA or 3TDES).
Other variations of TDEA, where two or three of the keys are identical, are no longer approved for applying cryptographic protection because of increased computing power or weaknesses in the algorithm.
（强调我的）。资料来源：http://csrc.nist.gov/publications/drafts/800-175/sp800-175b_draft.pdf