I would like to do a REST resource that could be represented as:
PDF (binary for download);
JSON (with structured data);
PDF (base64 encode)
My expectation is to create a URL like this:
http://api.mybank.com/accounts/{accountId}/statement?fromDate=2019-11
The Accept header as 'application/json' will return the statement information.
The Accept header as 'application/pdf' will return the statement in a PDF binary file.
And PDF encoded as base64? How I define this?
Content-Transfer-Encoding is not an HTTP, but email header.
Transfer-Encoding is used only for compression.
The Scenario:
I'm reading about JSON web tokens at this link (https://medium.com/vandium-software/5-easy-steps-to-understanding-json-web-tokens-jwt-1164c0adfcec). It outline how to create a JSON web token, you create a header and a payload, and then create a signature using the following pseudocode:
data = base64urlEncode( header ) + “.” + base64urlEncode( payload )
hashedData = hash( data, secret )
signature = base64urlEncode( hashedData )
My Question:
Why does the pseudocode use base64urlEncode when creating data and signature?
Scope Of What I Understand So Far:
Base64 allows you to express binary data using text characters from the Base64 set of 64 text characters. This is usually used when you have a set of data that you want to pass through some channel that might misinterpret some of the characters, but would not misinterpret Base64 characters, so you encode it using Base64 so that the data won't get misinterpreted. Base64 URL encoding, on the other hand, is analogous to Base64 encoding except that you use only a subset of the Base64 character set that does not include characters that have special meaning in URLs, so that if you use the Base64 URL encoded string in a URL, its meaning won't get misinterpreted.
Assuming my understanding there is correct, I'm trying to understand why base64urlEncode() is used in computing data and signature in the pseudocode above. Is the signature of a JSON web token going to be used somewhere in a URL? If so, why is data base64urlEncoded as well before hashing. Why not just encode the signature? Is there something about the hash function that would require its data parameter to be Base64 URL encoded?
When using the OAuth Implicit Grant, JWTs may be transferred as part of URL fragments.
That is just an example, but I guess in general it was presumed that JWTs might be passed through URLs, so base64urlEncodeing them makes sense.
The first line of the IETF JWT standard abstract even says:
JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties.
(Note that the OAuth Implicit Grant is no longer recommended to be used.)
From what I can understand, it's a straight forward process to validate a JWT signature. But when I use some online tools to do this for me, it doesn't match. How can I manually validate a JWT signature without using a JWT library? I'm needing a quick method (using available online tools) to demo how this is done.
I created my JWT on https://jwt.io/#debugger-io with the below info:
Algorithm: HS256
Secret: hONPMX3tHWIp9jwLDtoCUwFAtH0RwSK6
Header:
{
"alg": "HS256",
"typ": "JWT"
}
Payload:
{
"sub": "1234567890",
"name": "John Doe",
"iat": 1516239022
}
Verify Signature (section):
Secret value changed to above
"Checked" secret base64 encoded (whether this is checked or not, still get a different value)
JWT:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.wDQ2mU5n89f2HsHm1dluHGNebbXeNr748yJ9kUNDNCA
Manual JWT signature verification attempt:
Using a base64UrlEncode calculator (http://www.simplycalc.com/base64url-encode.php or https://www.base64encode.org/)
If I: (Not actual value on sites, modified to show what the tools would ultimately build for me)
base64UrlEncode("eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9") + "." + base64UrlEncode("eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ")
I get:
ZXlKaGJHY2lPaUpJVXpJMU5pSXNJblI1Y0NJNklrcFhWQ0o5.ZXlKemRXSWlPaUl4TWpNME5UWTNPRGt3SWl3aWJtRnRaU0k2SWtwdmFHNGdSRzlsSWl3aWFXRjBJam94TlRFMk1qTTVNREl5ZlE=
NOTE: there's some confusion on my part if I should be encoding the already encoded values, or use the already encoded values as-is.
(i.e. using base64UrlEncode("eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9") + "." + base64UrlEncode("eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ") vs "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ").
Regardless on which I should do, the end result still doesn't match the signature. I'm leaning towards that I should NOT re-encode the encoded value, whether that's true or not.
Then using a HMAC Generator calculator (https://codebeautify.org/hmac-generator or https://www.freeformatter.com/hmac-generator.html#ad-output)
(Not actual value on sites, modified to show what the tools would ultimately build for me)
HMACSHA256(
"ZXlKaGJHY2lPaUpJVXpJMU5pSXNJblI1Y0NJNklrcFhWQ0o5.ZXlKemRXSWlPaUl4TWpNME5UWTNPRGt3SWl3aWJtRnRaU0k2SWtwdmFHNGdSRzlsSWl3aWFXRjBJam94TlRFMk1qTTVNREl5ZlE=",
"hONPMX3tHWIp9jwLDtoCUwFAtH0RwSK6"
)
Which gets me:
a2de322575675ba19ec272e83634755d4c3c2cd74e9e23c8e4c45e1683536e01
And that doesn't match the signature portion of the JWT:
wDQ2mU5n89f2HsHm1dluHGNebbXeNr748yJ9kUNDNCAM != a2de322575675ba19ec272e83634755d4c3c2cd74e9e23c8e4c45e1683536e01
Purpose:
The reason I'm needing to confirm this is to prove the ability to validate that the JWT hasn't been tampered with, without decoding the JWT.
My clients web interface doesn't need to decode the JWT, so there's no need for them to install a jwt package for doing that. They just need to do a simple validation to confirm the JWT hasn't been tampered with (however unlikely that may be) before they store the JWT for future API calls.
It's all a matter of formats and encoding.
On https://jwt.io you get this token based on your input values and secret:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.3pIaKksiX9Zv8Jg-hWbrD24VhL36hBIFaNpA4fVx29M
We want to prove that the signature:
3pIaKksiX9Zv8Jg-hWbrD24VhL36hBIFaNpA4fVx29M
is correct.
The signature is a HMAC-SHA256 hash that is Base64url encoded.
(as described in RFC7515)
When you use the online HMAC generator to calculate a hash for
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ
with the secret
hONPMX3tHWIp9jwLDtoCUwFAtH0RwSK6
you get
de921a2a4b225fd66ff0983e8566eb0f6e1584bdfa84120568da40e1f571dbd3
as result, which is a HMAC-SHA256 value, but not Base64url encoded. This hash is a hexadecimal string representation of a large number.
To compare it with the value from https://jwt.io you need to convert the value from it's hexadecimal string representation back to a number and Base64url encode it.
The following script is doing that and also uses crypto-js to calculate it's own hash. This can also be a way for you to verify without JWT libraries.
var CryptoJS = require("crypto-js");
// the input values
var base64Header = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9";
var base64Payload = "eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ";
var secret = "hONPMX3tHWIp9jwLDtoCUwFAtH0RwSK6";
// two hashes from different online tools
var signatureJWTIO = "3pIaKksiX9Zv8Jg-hWbrD24VhL36hBIFaNpA4fVx29M";
var onlineCaluclatedHS256 = "de921a2a4b225fd66ff0983e8566eb0f6e1584bdfa84120568da40e1f571dbd3";
// hash calculation with Crypto-JS.
// The two replace expressions convert Base64 to Base64url format by replacing
// '+' with '-', '/' with '_' and stripping the '=' padding
var base64Signature = CryptoJS.HmacSHA256(base64Header + "." + base64Payload , secret).toString(CryptoJS.enc.Base64).replace(/\+/g,'-').replace(/\//g,'_').replace(/\=+$/m,'');
// converting the online calculated value to Base64 representation
var base64hash = new Buffer.from(onlineCaluclatedHS256, 'hex').toString('base64').replace(/\//g,'_').replace(/\+/g,'-').replace(/\=+$/m,'')
// the results:
console.log("Signature from JWT.IO : " + signatureJWTIO);
console.log("NodeJS calculated hash : " + base64Signature);
console.log("online calulated hash (converted) : " + base64hash);
The results are:
Signature from JWT.IO : 3pIaKksiX9Zv8Jg-hWbrD24VhL36hBIFaNpA4fVx29M
NodeJS calculated hash : 3pIaKksiX9Zv8Jg-hWbrD24VhL36hBIFaNpA4fVx29M
online calulated hash (converted) : 3pIaKksiX9Zv8Jg-hWbrD24VhL36hBIFaNpA4fVx29M
identical!
Conclusion:
The values calculated by the different online tools are all correct but not directly comparable due to different formats and encodings.
A little script as shown above might be a better solution.
I had the same problem until I figured out that I was using plain base64 encoding instead of base64url.
There are also some minor details in between.
Here is the step-by-step manual that will, hopefully, make the whole process much more clear.
Notes
Note 1: You must remove all spaces and newlines from your JSON strings (header and payload).
It is implicitly done on jwt.io when you generate a JWT token.
Note 2: To convert JSON string to base64url string on cryptii.com create the following configuration:
First view: Text
Second view: Encode
Encoding: Base64
Variant: Standard 'base64url' (RFC 4648 §5)
Third view: Text
Note 3: To convert HMAC HEX code (signature) to base64url string on cryptii.com create the following configuration:
First view: Bytes
Format: Hexadecimal
Group by: None
Second view: Encode
Encoding: Base64
Variant: Standard 'base64url' (RFC 4648 §5)
Third view: Text
Manual
You are going to need only two online tools:
[Tool 1]: cryptii.com - for base64url encoding,
[Tool 2]: codebeautify.org - for HMAC calculation.
On cryptii.com you can do both base64url encoding/decoding and also HMAC calculation, but for HMAC you need to provide a HEX key which is different from the input on jwt.io, so I used a separate service for HMAC calculation.
Input data
In this manual I used the following data:
Header:
{"alg":"HS256","typ":"JWT"}
Payload:
{"sub":"1234567890","name":"John Doe","iat":1516239022}
Secret (key):
The Earth is flat!
The secret is not base64 encoded.
Step 1: Convert header [Tool 1]
Header (plain text):
{"alg":"HS256","typ":"JWT"}
Header (base64url encoded):
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
Step 2: Convert payload [Tool 1]
Payload (plain text):
{"sub":"1234567890","name":"John Doe","iat":1516239022}
Payload (base64url encoded):
eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ
Step 3: Calculate HMAC code (signature) [Tool 2]
Calculate HMAC using SHA256 algorithm.
Input string (base64url encoded header and payload, concatenated with a dot):
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ
Calculated code (HEX number):
c8a9ae59f3d64564364a864d22490cc666c74c66a3822be04a9a9287a707b352
The calculated HMAC code is a HEX representation of the signature.
Note: it should not be encoded to base64url as a plain text string but as a sequence of bytes.
Step 4: Encode calculated HMAC code to base64url [Tool 1]:
Signature (Bytes):
c8a9ae59f3d64564364a864d22490cc666c74c66a3822be04a9a9287a707b352
Signature (base64url encoded):
yKmuWfPWRWQ2SoZNIkkMxmbHTGajgivgSpqSh6cHs1I
Summary
Here are our results (all base64url encoded):
Header:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
Payload:
eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ
Signature:
yKmuWfPWRWQ2SoZNIkkMxmbHTGajgivgSpqSh6cHs1I
The results from jwt.io:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.yKmuWfPWRWQ2SoZNIkkMxmbHTGajgivgSpqSh6cHs1I
As you can see, all three parts are identical.
I'm trying to make a 'DEL' REST request using Soapui Pro. One of the parameters includes a value containing '+' (which gets treated as SPACE if not UTF-8 encoded). Soapui doesn't seem to URL encode the request even though tried to re-enforce encoding in the REST request step.
Secondly, i tried to pass UTF-8 encoded value (encoded by a groovy step). But Soapui seems to, some how, automatically. decode the value before sending. Am i missing something here? Please help.
Sample request (RAW)
Sensitive data masked by XXXXX, YYYYY
DELETE https://XXXXXservices.com/XXXXX_services/ogw/emf/securityShare/888247189312/members?shareId=8882015810875&memberIds=XXXXX&auth-username=YYYYY&auth-nonce=XIX9UL9UBIE2L8K&auth-sharedkeyid=System&auth-expiresby=1414607713258&auth-algorithm=HMACSHA256&auth-signature=9JmAxG6rkqZe0Fu+zPQIh9Eh3tazDoE1YBZFxgIRLMc= HTTP/1.1
Accept-Encoding: gzip,deflate
Host: XXXXXservices.com
Connection: Keep-Alive
User-Agent: Apache-HttpClient/4.1.1 (java 1.5)
While analyzing the HTTP Requests OF a website. I found that in one of the POST request it sends three postdata to the server the first one was SAML data first base64 encoded then urlencoded.
But I am not able to figure out the value of other two postvars. One thing I am sure about is that it is not using any encryption methods like md5 or sha1 etc. COZ the response text contains my user name value which according to my research is neither stored in session variable or cookies means this encoding of post data can be reversed. So I am guessing that may be my user name "RAHUL" is inside one of these post variables. But am unable to read it.
First String:
sRrWj1zUsisp/UylJiEf/pekY//ok1nYAAcvJfkxL9kMEggMAX0jTTs1hPPKTU9d1u/qgdq6eIvS
nk3NT6KkR9bKiGyQKY5iJ39JXGNlBvxs3F9N7TMHUBeNZ2BSDg05dTyYtdiVffRDnQ5KgDCy7ZjG
Lzj5J3x3LJumTau7aFc5CZ2b4xqzEPc4kGVcg/6l5D7Hxonp6U/0DnIzemcrXfb95X40CidNmz1J
PlGaeZzgAsA619vhs3AlGPNZ/Nbbm7IsJlVcKY6TvigrP0jMCp/0BvYb45gztvaJicN43JrNUsgc
+CLKaTvxflkLhul/sAe5Gbm83AtR/kNKQZf2hg==
Second String:
Og5+F9RTHNs7NqUEYpgGSshInxZQzCP3gU2fkI8VnS60Ce2hmurlTLn6IcdP63zUkrDbdA2/+J00
DNgD15yW2lNo5Zi3PdfEEOxFjw8L5/RFwoIrMzTzS8csZaWqSAfqW1GiE4hbpAgeKZ4pXrmTLy2A
/AfT90uCptaoEa19qzD6/5o2+G4lCeJf5ZUMeZRMLvX3U909TlzCggf9KsHeJpfXGnGEefu9o0V9
kbQ5FzLEuao9ByCnXaFBEcDBDAFljrK0fsqJyLyv2gnhj4IOcCAEowa9N6tBsu/ngac9uR+NHY4+
r4l67i+nt5CRZ9PRLq/hT2qCoy6PguhDOEHbgg==
When I decoded the above strings using base64 decoder it returns unreadable value. I want to know what to do next so as to get useful data inside it.
I am pasting the complete post request including Headers and form data.
HEADERS
Host: xxxx.xxxx.xxxx.xxxxxxx
User-Agent: Mozilla/5.0 (Windows NT 6.2; rv:20.0) Gecko/20100101 Firefox/20.0
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer:xxx.xxx.com/xxxxxx/adsf
Cookie: _abc_abc_session=1032510200e6bf9a8ae265553120e1ca;
AWSELB=F7610D8306188BFF856DC4E8C0134950D9FBEC546F2ACFBA970F103CC9E2B9074253115B0BB906564BB68191596A2637A0D1F52106813C785600B014A199891F5B8C6C8420
Connection: keep-alive
Content-Type: application/x-www-form-urlencoded
Content-Length: 8725
FORM
TARGET: www.XXVVVVVVVVVF.com/sessions/consume
SAMLResponse: XXXXXXXXXX
APID: ap_00001
pca_red74:
KiiYkBzqSHEKWu2Q//CgZg47iEBSOkU1Ew3yaUIAQNqHAf8AwZVLQXdNw5ZF0B67WJH46JDKQ/sP
Cypp2sofHA/Eq0gXMoH7yZt3RG0LXTuNANYNr/chOx4kks0/fINjpowPXTiSkWc0bsXimWH62BZy
mq7TATEsXM6w4ywu1cVTP+/DlfNy3Mf0V3VVwEjMWwtR/3X8zKgtRJKMTtwe/YGhus6YefSEknPO
pO9oy3zdDy0Yp7qRp93tPAdxRSXyIsJs5bJlefH8o5QSzsk7hlBhQFhd/OlKpMCsYMDSOHa+FJ1K
AqEWgH0eMzczO6LFhVdhAAm3DFaAvxL4u+DkuQ==
pca_red75:
tU48SalKFzVys9fZR1Se+5xP1dlOh9SlbYBT/Ct6BGiyIFEVEdyq2XR7BDuz/0BAsMfGwhgwI3Ws
uNk6KnEyOBIX+9u0eFer/VoHkGydw8310fGxJiiq13BYHnkzk9OLZCdD43VF27a6SvEtaA/LXnm4
ZrURgpoFWtfBmaC4zIkHkYgXW5wTYeJ1Ze0rgmBYPFlms2BefeRricA68NR3OsbSoCmwIKfuWe+2
esM4RN8t9jG/nccM2EeluDXRKJHA09O02Lq7KBhZw5o2OBCQ7nDc9p47Poli0as1yo+ylHfjJOag
qCeVuPBCLEwpJL74CreuzJGAYqSOVA9BOx5SQA==