Usage is very straightforward:

julia> using SHA

julia> bytes2hex(sha256("test"))
"9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08"

Each exported function (at the time of this writing, SHA-1, SHA-2 224, 256, 384 and 512, and SHA-3 224, 256, 384 and 512 functions are implemented) takes in either an Array{UInt8}, a ByteString or an IO object. This makes it trivial to checksum a file:

shell> cat /tmp/test.txt
test
julia> using SHA

julia> open("/tmp/test.txt") do f
           sha2_256(f)
       end
32-element Array{UInt8,1}:
 0x9f
 0x86
 0xd0
 0x81
 0x88
 0x4c
 0x7d
 0x65
    ⋮
 0x5d
 0x6c
 0x15
 0xb0
 0xf0
 0x0a
 0x08

Note the lack of a newline at the end of /tmp/text.txt. Julia automatically inserts a newline before the julia> prompt.

Due to the colloquial usage of sha256 to refer to sha2_256, convenience functions are provided, mapping shaxxx() function calls to sha2_xxx(). For SHA-3, no such colloquialisms exist and the user must use the full sha3_xxx() names.

shaxxx() takes AbstractString and array-like objects (NTuple and Array) with elements of type UInt8.

Note that, at the time of this writing, the SHA3 code is not optimized, and as such is roughly an order of magnitude slower than SHA2. Pull requests are welcome.