ruby – base64编码长度参数

发布时间：2020-12-17 03:39:04 所属栏目：百科来源：网络整理

导读：我正在解码base64字符串,修改它,并用 Ruby重新编码它.重新编码时的问题是ruby编码库在60个左右的字符后添加了一个换行符.如何告诉它没有每行限制的最大字符数？ val = "QmFzZTY0IGlzIGEgZ2VuZXJpYyB0ZXJtIGZvciBhIG51bWJlciBvZiBzaW1pbGFyIGVuY29kaW5nIHNjaG

我正在解码base64字符串,修改它,并用 Ruby重新编码它.重新编码时的问题是ruby编码库在60个左右的字符后添加了一个换行符.如何告诉它没有每行限制的最大字符数？

val = "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"

decoded_val = Base64.decode64(val)
encoded_val = Base64.encode64(val)

#=> QmFzZTY0IGlzIGEgZ2VuZXJpYyB0ZXJtIGZvciBhIG51bWJlciBvZiBzaW1p
#   bGFyIGVuY29kaW5nIHNjaGVtZXMgdGhhdCBlbmNvZGUgYmluYXJ5IGRhdGEg
#   YnkgdHJlYXRpbmcgaXQgbnVtZXJpY2FsbHkgYW5kIHRyYW5zbGF0aW5nIGl0
#   IGludG8gYSBiYXNlIDY0IHJlcHJlc2VudGF0aW9uLiBUaGUgQmFzZTY0IHRl
#   cm0gb3JpZ2luYXRlcyBmcm9tIGEgc3BlY2lmaWMgTUlNRSBjb250ZW50IHRy
#   YW5zZmVyIGVuY29kaW5nLg0KDQpCYXNlNjQgZW5jb2Rpbmcgc2NoZW1lcyBh
#   cmUgY29tbW9ubHkgdXNlZCB3aGVuIHRoZXJlIGlzIGEgbmVlZCB0byBlbmNv
#   ZGUgYmluYXJ5IGRhdGEgdGhhdCBuZWVkcyBiZSBzdG9yZWQgYW5kIHRyYW5z
#   ZmVycmVkIG92ZXIgbWVkaWEgdGhhdCBhcmUgZGVzaWduZWQgdG8gZGVhbCB3
#   aXRoIHRleHR1YWwgZGF0YS4gVGhpcyBpcyB0byBlbnN1cmUgdGhhdCB0aGUg
#   ZGF0YSByZW1haW5zIGludGFjdCB3aXRob3V0IG1vZGlmaWNhdGlvbiBkdXJp
#   bmcgdHJhbnNwb3J0LiBCYXNlNjQgaXMgdXNlZCBjb21tb25seSBpbiBhIG51
#   bWJlciBvZiBhcHBsaWNhdGlvbnMgaW5jbHVkaW5nIGVtYWlsIHZpYSBNSU1F
#   LCBhbmQgc3RvcmluZyBjb21wbGV4IGRhdGEgaW4gWE1MLg==

解决方法

RFC 4648: The Base16,Base32,and Base64 Data Encodings有这个说：

3.3. Interpretation of Non-Alphabet Characters in Encoded Data
[…]
Implementations MUST reject the encoded data if it contains
characters outside the base alphabet when interpreting base-encoded
data,unless the specification referring to this document explicitly
states otherwise. Such specifications may instead state,as MIME
does,that characters outside the base encoding alphabet should
simply be ignored when interpreting data (“be liberal in what you
accept”). Note that this means that any adjacent carriage return/
line feed (CRLF) characters constitute “non-alphabet characters” and
are ignored.

所以换行很好,几乎所有东西都会忽略它们,即使它们没有严格遵守RFC 4648.

此外,fine manual还有这样的说法：

encode64(bin)

Returns the Base64-encoded version of bin. This method complies with RFC 2045. Line feeds are added to every 60 encoded charactors [sic].

所以60个字符的行长度是有意和指定的.如果你想要严格的RFC 4648 Base64(即没有新行),那么有strict_encode64：

strict_encode64(bin)

Returns the Base64-encoded version of bin. This method complies with RFC 4648. No line feeds are added.

所以你可以说Base64.strict_encode64(val)来获取你正在寻找的输出.

作为参考,这是relevant section of RFC 2045：

6.8. Base64 Content-Transfer-Encoding
[…]
The encoded output stream must be represented in lines of no more
than 76 characters each. All line breaks or other characters not
found in Table 1 must be ignored by decoding software.

因此,60字符的行长度有些随意,但符合RFC 2045,因为60< 76.

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!