Only 143 max filename length for crypt remote

[olihey]

The documentation of the filename encryption using the standard method says a filename (and directory name) can have up to 156 characters. But I just ran into an issue with a name of 156 characters length and a crypt remote.
After some trial and error I could get up to 143 characters (see below).

C:\>rclone.exe mkdir "localenc:/Lorem ipsum dolor sit amet, consectetur adipiscing elit. Maecenas at elit augue. Maecenas vitae eros tempus dui mattis egestas. Sed ornare orci "
2018/01/31 18:39:06 ERROR : Attempt 1/3 failed with 1 errors and: mkdir \s2uv1i79cph8peena5qj91ir578i1ubdrokc5l03etvb6lhdebvh8pa82468net5427lsis2c3flrlb7j6kkfbnfdc0hl436buj5rgu5l6osotdpcghu0ovg404lc6od4gtt1r4tr9ihoks4vlhrckj5j3puskers364qih3tquemuf4ogud8kvce87d3odjv7a5u4ujns3jr99uikk986fhg33u932i7ooq38e4in2r6lat050fblg0lj4305qg: The filename or extension is too long.
2018/01/31 18:39:06 ERROR : Attempt 2/3 failed with 1 errors and: mkdir \s2uv1i79cph8peena5qj91ir578i1ubdrokc5l03etvb6lhdebvh8pa82468net5427lsis2c3flrlb7j6kkfbnfdc0hl436buj5rgu5l6osotdpcghu0ovg404lc6od4gtt1r4tr9ihoks4vlhrckj5j3puskers364qih3tquemuf4ogud8kvce87d3odjv7a5u4ujns3jr99uikk986fhg33u932i7ooq38e4in2r6lat050fblg0lj4305qg: The filename or extension is too long.
2018/01/31 18:39:06 ERROR : Attempt 3/3 failed with 1 errors and: mkdir \s2uv1i79cph8peena5qj91ir578i1ubdrokc5l03etvb6lhdebvh8pa82468net5427lsis2c3flrlb7j6kkfbnfdc0hl436buj5rgu5l6osotdpcghu0ovg404lc6od4gtt1r4tr9ihoks4vlhrckj5j3puskers364qih3tquemuf4ogud8kvce87d3odjv7a5u4ujns3jr99uikk986fhg33u932i7ooq38e4in2r6lat050fblg0lj4305qg: The filename or extension is too long.
2018/01/31 18:39:06 Failed to mkdir: mkdir \s2uv1i79cph8peena5qj91ir578i1ubdrokc5l03etvb6lhdebvh8pa82468net5427lsis2c3flrlb7j6kkfbnfdc0hl436buj5rgu5l6osotdpcghu0ovg404lc6od4gtt1r4tr9ihoks4vlhrckj5j3puskers364qih3tquemuf4ogud8kvce87d3odjv7a5u4ujns3jr99uikk986fhg33u932i7ooq38e4in2r6lat050fblg0lj4305qg: The filename or extension is too long.

C:\>rclone.exe mkdir "localenc:/Lorem ipsum dolor sit amet, consectetur adipiscing elit. Maecenas at elit augue. Maecenas vitae eros tempus dui mattis egestas. Sed ornare orci"

Maybe we should update the documentation?

Relevant .rclone.conf snippet

[local]
type = local
nounc = true

[localenc]
type = crypt
remote = local:/
filename_encryption = standard
password = sdMYVIRrPJMKUEnW-BxBAXSLMzC50O1h
password2 = S1tK9bm7Yw6fS6tUCOF2ONd7L_w

Tested with latest master

[ncw]

That number varies acording to exactly which remote you use. I ran rclone info secret hidden command on linux and got the same number so I agree - want to send a PR?

$ rclone mkdir secret:
$ rclone info secret:
2018/01/31 20:28:19 EME operates on 1 to 128 block-cipher blocks, you passed 513
2018/01/31 20:28:19 EME operates on 1 to 128 block-cipher blocks, you passed 257
2018/01/31 20:28:19 EME operates on 1 to 128 block-cipher blocks, you passed 129
// secret
charNeedsEscaping = []byte{
	0x00, 0x2F
}
maxFileLength = 143
canWriteUnnormalized = true
canReadUnnormalized   = true
canReadRenormalized   = false
canStream = true

$ rclone config show secret
--------------------
[secret]
type = crypt
remote = /tmp/secret
filename_encryption = standard
password = *** ENCRYPTED ***
--------------------