# HMAC\_SHA256 not matching in Julia and python
**URL:** https://discourse.julialang.org/t/hmac-sha256-not-matching-in-julia-and-python/73873
**Category:** General Usage
**Tags:** question
**Created:** [December 31, 2021, 7:30pm UTC](https://discourse.julialang.org/t/hmac-sha256-not-matching-in-julia-and-python/73873 "2021-12-31T19:30:42Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@AMJ](https://discourse.julialang.org/u/AMJ)
#### Post date: [December 31, 2021, 7:30pm UTC](https://discourse.julialang.org/t/hmac-sha256-not-matching-in-julia-and-python/73873/1 "2021-12-31T19:30:43Z")
I have to encode a pass phrase with a “api secret” in SHA256 then base encode64 and send it to the rest api server but I can not manage to match what I get out of python with Julia.
This is the python code
```julia
import hmac
import hashlib
import base64
from urllib.parse import urlencode
secret = "string"
pass = "string"
passphrase = base64.b64encode(hmac.new(secret.encode('utf-8'), pass.encode('utf-8'), hashlib.sha256).digest())
```
I used Nettle.jl for HMAC SHA256 Julia but I get a totally different output
```julia
secret = "string"
pass = "string"
passphrase = base64encode(hexdigest("sha256", secret, pass))
```
There is SHA.jl and it has apparently the same function which is hmac\_sha2\_256 but when I set my inputs as “secret” and “pass” it gives “no method matching” for the first input. I tried to convert the first input to UInt8 with transcode() function still gives the same error. What am I doing wrong ?
---
### Author:  [@AMJ](https://discourse.julialang.org/u/AMJ)
#### Post date: [January 1, 2022, 10:26am UTC](https://discourse.julialang.org/t/hmac-sha256-not-matching-in-julia-and-python/73873/2 "2022-01-01T10:26:43Z")
I got the same value as python gives with the SHA.jl. There is no documentation for HMAC functionality in the SHA.jl albeit having all the SHA1 to 3. If you search `hmac_sha256` in the terminal you get the bellow explanation:
```julia
No documentation found.
SHA.hmac_sha256 is a Function.
# 5 methods for generic function "hmac_sha256":
[1] hmac_sha256(key::Vector{UInt8}, data::Union{Tuple{Vararg{UInt8, N}} where N, AbstractVector{UInt8}}) in SHA at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/SHA/src/SHA.jl:99
[2] hmac_sha256(key::Vector{UInt8}, io::IO) in SHA at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/SHA/src/SHA.jl:125
[3] hmac_sha256(key::Vector{UInt8}, io::IO, chunk_size) in SHA at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/SHA/src/SHA.jl:125
[4] hmac_sha256(key::Vector{UInt8}, str::String) in SHA at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/SHA/src/SHA.jl:109
[5] hmac_sha256(key::Vector{UInt8}, str::AbstractString) in SHA at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/SHA/src/SHA.jl:108
```
Which I was mistakenly putting a `string` as my key and solved with a `Vector{UInt8}(secret)` input as key.
I still could not get the Nettle.jl to match, I don’t know what Im doing wrong there.
---
### Author:  [@StefanKarpinski](https://discourse.julialang.org/u/StefanKarpinski)
#### Post date: [January 1, 2022, 1:09pm UTC](https://discourse.julialang.org/t/hmac-sha256-not-matching-in-julia-and-python/73873/3 "2022-01-01T13:09:15Z")
If there’s some API or documentation improvement to be made, please do open an issue on GitHub.
---
### Author:  [@AMJ](https://discourse.julialang.org/u/AMJ)
#### Post date: [January 2, 2022, 8:12am UTC](https://discourse.julialang.org/t/hmac-sha256-not-matching-in-julia-and-python/73873/4 "2022-01-02T08:12:56Z")
Alright will do.
---
### Author:  [@jakewilliami](https://discourse.julialang.org/u/jakewilliami)
#### Post date: [May 8, 2022, 11:28am UTC](https://discourse.julialang.org/t/hmac-sha256-not-matching-in-julia-and-python/73873/5 "2022-05-08T11:28:08Z")
For an example of how this works:
```julia
using SHA
key = "mykey"
msg = "mymsg"
enc = bytes2hex(hmac_sha256(Vector{UInt8}(key), msg))
```
This should be equivalent to Python’s
```python
import hmac
import hashlib
key = "mykey"
msg = "mymsg"
encoding = 'utf-8' # or 'ascii'
enc = hmac.new(key.encode(encoding), msg.encode(encoding), hashlib.sha256).hexdigest()
```