Ruby SHA2 摘要不正确的文档或我的 IRB 中的问题？

Question

文档@ http://www.ruby-doc.org/stdlib-1.9.3/libdoc/digest/rdoc/Digest/SHA2.html显示:

Digest::SHA256.new.digest_length * 8
 #=> 512
Digest::SHA384.new.digest_length * 8
 #=> 1024
Digest::SHA512.new.digest_length * 8
 #=> 1024

这是我在 2.1.3 中的输出:

Digest::SHA256.new.digest_length * 8
 #=> 256 
Digest::SHA384.new.digest_length * 8
 #=> 384 
Digest::SHA512.new.digest_length * 8
 #=> 512

为什么我的 block 长度输出与 Ruby 文档不同？

Answer 1

文档好像有错别字，你看，

block_length → Integer
Returns the block length of the digest in bytes.

Digest::SHA256.new.digest_length * 8
# => 512
Digest::SHA384.new.digest_length * 8
# => 1024
Digest::SHA512.new.digest_length * 8
# => 1024

digest_length → Integer
Returns the length of the hash value of the digest in bytes.

Digest::SHA256.new.digest_length * 8
# => 256
Digest::SHA384.new.digest_length * 8
# => 384
Digest::SHA512.new.digest_length * 8
# => 512

两者都在示例中使用了digest_length。

但它应该是，

block_length → Integer
Returns the block length of the digest in bytes.

Digest::SHA256.new.block_length * 8
# => 512
Digest::SHA384.new.block_length * 8
# => 1024
Digest::SHA512.new.block_length * 8
# => 1024

digest_length → Integer
Returns the length of the hash value of the digest in bytes.

Digest::SHA256.new.digest_length * 8
# => 256
Digest::SHA384.new.digest_length * 8
# => 384
Digest::SHA512.new.digest_length * 8
# => 512