Hi in the backend which is written in PHP we have the following function for decryption
openssl_decrypt($myMessage, 'AES-256-CBC',
'myKeyPlainText', 0, 'myVIplainText');
both key and vi are in plainText.
I want to encrypt my message in front end using Javascript. I use CryptoJS and the code is the following
var encrypted = CryptoJS.AES.encrypt(message, 'myKeyPlainText, {
iv: 'myVIplainText,
mode: CryptoJS.mode.CBC
});
I always get false from openssl_decrypt. What am I doing wrong?
Related
I am trying to create JWS Tokens using Elixir.
What I've got:
RSA Private key
Base 64 encoded sha256 cert thumbprint
Token header
Token body
What I need:
Token signature
JWS header looks like this
{
"x5t#S256": {{ cert thumbprint }},
"alg":"RS256"
}
To get the header token I just convert it to base64 and it's finished. Same with token body, I just convert the payload to base64.
The problem is getting token signature. As I understand it should be done like this:
token signature = base64(rsa-sha256(token header + "." + token body))
Q1: Is my logic here correct?
Q2: How to do the rsa-sha256 encryption on Elixir? Or is it the same thing as :crypto.hash(sha256, ...)?
I've not worked with JWS in Elixir, but I decided to try it as an exercise. You can generate the JWS signature using RSA like this:
rsa_private_key = JOSE.JWK.from_pem_file("rsa-2048.pem")
header = %{"alg" => "RS256"}
payload = %{"example" => "foo"}
JOSE.JWT.sign(rsa_private_key, header, payload)
Output:
{%{alg: :jose_jws_alg_rsa_pkcs1_v1_5},
%{
"payload" => "eyJleGFtcGxlIjoiZm9vIn0",
"protected" => "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9",
"signature" => "T2llXS2pGN-jev10Xd5EZQmaEih_dn9DIn5FJJg8ocEwIpNLupEWiNLz-5mP21z9JGpyYPFaRuq77AtKL67nP7KMDTpKKYJonOxQdL31sHU4vTKBRf-2XcVbDLGkST5dUMUWHOS106Sw_0x7DSiuFBUzkkYQ_lZKES8idVUp88Kx4uWU65Yoti0_Pu7aVLRGWDu0EiMjzuTPTBkMoib21VEVBqrJ4jiKXFudEFiNNSaV_GOH9yNZqyxwl4RhCYYT9U-Mda8Dc7xPjQk0LaJhwlaV91OhxJQHP2fGR8XkznHFlRRHTEsesYgl9OKZuSzVXoffydLc1VotphKUnG1WZQ"
}}
And if you want it in short form:
JOSE.JWT.sign(rsa_private_key, header, payload) |> JOSE.JWS.compact
Produces:
{%{alg: :jose_jws_alg_rsa_pkcs1_v1_5},
"eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJleGFtcGxlIjoiZm9vIn0.T2llXS2pGN-jev10Xd5EZQmaEih_dn9DIn5FJJg8ocEwIpNLupEWiNLz-5mP21z9JGpyYPFaRuq77AtKL67nP7KMDTpKKYJonOxQdL31sHU4vTKBRf-2XcVbDLGkST5dUMUWHOS106Sw_0x7DSiuFBUzkkYQ_lZKES8idVUp88Kx4uWU65Yoti0_Pu7aVLRGWDu0EiMjzuTPTBkMoib21VEVBqrJ4jiKXFudEFiNNSaV_GOH9yNZqyxwl4RhCYYT9U-Mda8Dc7xPjQk0LaJhwlaV91OhxJQHP2fGR8XkznHFlRRHTEsesYgl9OKZuSzVXoffydLc1VotphKUnG1WZQ"}
Here is the public key if you want to verify it:
-----BEGIN RSA PUBLIC KEY-----
MIIBCgKCAQEAtRPXSP1W+5sgVLeRFYrrF6L7+gaEkPOWV2FDtPL/vRQH77bicJYb
oVytE/8JyHj8kH24hxwCy2LFl5fZLaIrqYBy1B1t8LtxTRVhi3JIc76IGZ3dfxrz
Dnv94Vu9BRxE7y37f7w8ulDVlGpmJhfCIMj8SYJrFWgHlQB2u7c/B43RE6uphRfD
nr4FkJ3ChUFKhuVZHm27r5/CllHNhMejA/WawtlWKdU33In1Xp2O+GxjLKoYuGGQ
U9MdrismDtn6bVcq5K97bByxelJel2rUG4sbtQk01gVtfun63rSzOP9EkNJOoRll
YDm3HQlDUY7+D9AMG3XlQuR7tlDXQtGIJQIDAQAB
-----END RSA PUBLIC KEY-----
see this example on JWT Auth with an Elixir on Phoenix
using :bcrypt_elixir, and :guardian
I want to update Google AMP cache, so I need to sign an URL as described here.
My main issue: I'm struggling massively with how I should get my certificates/keys and how to include them in my code below.
I just can't find any all covering instructions for Windows and IIS.
I have been reading these posts:
Using /update-cache requests to update AMP pages
How can I sign a file using RSA and SHA256 with .NET?
I don't want to use my computer's certificate store as described in the second post. I'd rather use files on disk for both public and private keys.
From my production server IIS, I exported my certificate to a .pfx file, from which I then extracted the private key and certificate using the instructions on the bottom of this site.
The server.key contains -----BEGIN RSA PRIVATE KEY-----, which If I use that to load into the privateCert variable in the code below throws error Cannot find the requested object.
What I have gotten from my SSL provider:
www_example_com.crt, www_example_com.p7b, the certificate code (see below).
Steps I've taken:
I created test-public-key.cer by opening www_example.com.crt and using the Copy to file wizard to copy it to a base64 encoded .cer file.
I saved certificate code I received from my SSL provider as file test-private-key.cer.
When I run the following code I get error
Object reference not set to an instance of an object.
on line key.FromXmlString(privateCert.PrivateKey.ToXmlString(True))
Dim publicCert As X509Certificate2 = New X509Certificate2("C:\temp\_certificates\test-public-key.cer")
Dim privateCert As X509Certificate2 = New X509Certificate2("C:\temp\_certificates\test-private-key.cer")
'Round-trip the key to XML and back, there might be a better way but this works
Dim key As RSACryptoServiceProvider = New RSACryptoServiceProvider
key.FromXmlString(privateCert.PrivateKey.ToXmlString(True))
'Create some data to sign
Dim data() As Byte = System.Text.Encoding.Unicode.GetBytes(signatureUrl)
'Sign the data
Dim sig() As Byte = key.SignData(data, CryptoConfig.MapNameToOID("SHA256"))
Dim AMPURLSignature As String = EncodeTo64(sig.ToString)
'Lastly, the verification can be done directly with the certificate's public key without need for the reconstruction as we did with the private key:
key = CType(publicCert.PublicKey.Key, RSACryptoServiceProvider)
If Not key.VerifyData(data, CryptoConfig.MapNameToOID("SHA256"), sig) Then
Throw New CryptographicException
End If
EncodeTo64 function
Public Shared Function EncodeTo64(ByVal toEncode As String) As String
Dim toEncodeAsBytes As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(toEncode)
Dim returnValue As String = System.Convert.ToBase64String(toEncodeAsBytes)
Return returnValue
End Function
certificate code
-----BEGIN CERTIFICATE-----
MIIF (...) DXuJ
-----END CERTIFICATE-----
UPDATE 1
I was able to generate a mysite.pfx file by following the export steps on this page.
In the wizard I made sure to select "Yes, export the private key" and I added a password. The rest of the steps I followed verbatim.
I then also ran these commands:
openssl pkcs12 -in mysite.pfx -nocerts -out private-key-VPS.pem
penssl pkcs12 -in mysite.pfx -clcerts -nokeys -out certificate-VPS.pem
I ended up with private-key-VPS.pem and a certificate-VPS.pem files
I'm aware the steps to get the mysite.pfx are slightly different than what #CodeFuller described, but so far so good?
I then added code:
Dim certificate As X509Certificate2 = New X509Certificate2("C:\temp\_certificates\prodserverV2\mysite.pfx", "mypwd")
Dim rsa As RSA = certificate.GetRSAPrivateKey()
Dim data() As Byte = System.Text.Encoding.Unicode.GetBytes(signatureUrl)
Dim sig() As Byte = rsa.SignData(data, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1)
Dim AMPURLSignature As String = EncodeTo64(sig.ToString)
But there I get 4 errors:
GetRSAPrivateKey' is not a member of 'X509Certificate2'.
'SignData' is not a member of 'RSA'.
'HashAlgorithmName' is not declared. It may be inaccessible due to its protection level.
'RSASignaturePadding' is not declared. It may be inaccessible due to its protection level.
UPDATE 2
Thanks #CodeFuller! I targeted framework 4.6.1 and now seem to be 1 step further. I end up with an URL like this: https://www-mysite-com.cdn.ampproject.org/update-cache/c/s/www.mysite.com/articles/270/newarticle1/amp?amp_action=flush&_ts=1522939248&_url_signature=U30zdGVtLkJ5uGVbRQ==. How can I now check if it's a valid URL?
I'm checking section "Generate the RSA key" on this page, but I'm confused, since I actually already just coded these steps or not? How can I check whether the URL I now end up with is valid?
UPDATE 3
Ok, I tried your new code. Still get the URL signature verification error. I tried with both the /amp URL of my article and without the /amp part in my URL. Both result in the same URL signature verification error.
I noticed when I print the final URL to my website (see code below), the URL reads:
https://www-toptrouwen-nl.cdn.ampproject.org/update-cache/c/s/www.toptrouwen.nl/artikelen/132/het-uitwisselen-van-de-trouwringen-hoe-voorkom-je-bloopers/amp?amp_action=flush&_ts=1523094395&_url_signature=U3lzdGVrLkn5dGVbXQ==
Notice that where the parameters should be amp_ts and amp_url_signature, they now are _ts and _url_signature respectively.
I tried editing the URL before I do the call to Google by manually renaming parameters _ts and _url_signature to amp_ts and amp_url_signature. But I guess that would result in a difference between the signature and the actual URL. Could it be that somehow my code botches the & character and therefore when I rename these manually later it always result in a signature verification? Do you see what I could fix in my code?
BTW: I tried replacing & with %26 in code-behind before signing the URL but then I get a Google 404 error:
The requested URL /update-cache/c/s/www.toptrouwen.nl/artikelen/132/het-uitwisselen-van-de-trouwringen-hoe-voorkom-je-bloopers/amp?amp_action=flush%26amp_ts=1523094395%26amp_url_signature=U3lzdGVrLkJ1dGVbXQ== was not found on this server. That’s all we know.
My code:
Dim ampBaseUrl As String = "https://www-toptrouwen-nl.cdn.ampproject.org"
Dim signatureUrl As String = "/update-cache/c/s/www.toptrouwen.nl/artikelen/132/het-uitwisselen-van-de-trouwringen-hoe-voorkom-je-bloopers/amp?amp_action=flush&_ts=" + tStamp
Dim rsa As RSA = certificate.GetRSAPrivateKey()
Dim data() As Byte = System.Text.Encoding.ASCII.GetBytes(signatureUrl)
Dim sig() As Byte = rsa.SignData(data, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1)
Dim AMPURLSignature As String = EncodeTo64(sig.ToString)
Dim url As String = ampBaseUrl + signatureUrl + "&_url_signature=" + AMPURLSignature
ltStatus.Text = "AMP URL:<a target='_blank' href='" + url + "'>" + url + "</a>"
Also, I'm sure this page exists in Google AMP cache, since I can see and request it in Google's search results on my mobile device.
UPDATE 4
I'm getting close I think and also getting some extra help, see here: https://github.com/ampproject/amphtml/issues/14483#issuecomment-380549060
What I'm trying now to make it easier for others to test as well: Instead of depending on my SSL I now ran the following commands to get a public and private key
openssl genrsa 2048 > private-key.pem
openssl rsa -in private-key.pem -pubout >public-key.pem
I now have files private-key.pem and public-key.pem
I'll rename public-key.pem to apikey.pub and place that on https://example.com/.well-known/amphtml/apikey.pub
I want to take the easiest approach recommended by #CodeFuller and create a .pfx file that I can then load into a variable of type X509Certificate2.
When I run this command:
openssl pkcs12 -export -out keys.pfx -inkey private-key.pem -in public-key.pem
I get the error: unable to load certificates
But this time I don't have a .crt file, only a public-key.pem. How can I get a .pfx file? I already checked here.
I saved certificate code I received from my SSL provider as file
test-private-key.cer
...
certificate code
-----BEGIN CERTIFICATE-----
MIIF (...) DXuJ
-----END CERTIFICATE-----
The file stored in a format
-----BEGIN CERTIFICATE-----
MIIF (...) DXuJ
-----END CERTIFICATE-----
is a certificate which basically contains a public key. It does not contain private key. That's why when you create instance of X509Certificate2 from such file, it's HasPrivateKey property is set to False and PrivateKey returns Nothing, and following statement expectedly throws NullReferenceException:
privateCert.PrivateKey.ToXmlString(True)
In order to sign the data, you need a private key. Private keys have the following format
-----BEGIN RSA PRIVATE KEY-----
MIICXQ...B7Bou+
-----END RSA PRIVATE KEY-----
Such private keys are usually stored in *.key or *.pem (Privacy Enhanced Mail) files. There is no built-in way to load instance of X509Certificate2 from pem file. There are a lot of code samples available how to do it, you will find them in the question linked above. However the easiest solution will be to create pfx file (containing both private and public keys). Then you could easily load pfx with corresponding constructor of X509Certificate2.
Creation of pfx file is very easy with SSL tool. If private.key contains private key (-----BEGIN RSA PRIVATE KEY-----) and public.crt contains public key (-----BEGIN CERTIFICATE-----), they you could create pfx file with the following command:
openssl pkcs12 -export -out keys.pfx -inkey private.key -in
public.crt
You will be asked to enter the password. This password will also be used when you load the key to X509Certificate2:
Dim certificate As X509Certificate2 = New X509Certificate2("d:\CodeFuller\_days\2018.04.05\keys.pfx", "Password here")
Now HasPrivateKey property is set to True and PrivateKey returns the instance of RSACryptoServiceProvider.
UPDATE
Regarding this code:
'Round-trip the key to XML and back, there might be a better way but this works
Dim key As RSACryptoServiceProvider = New
RSACryptoServiceProvider
key.FromXmlString(privateCert.PrivateKey.ToXmlString(True))
The instance of RSACryptoServiceProvider is actually stored in certificate.PrivateKey so you could avoid above code and replace it with:
Dim provider As RSACryptoServiceProvider = certificate.PrivateKey
However your current SignData() call will not work:
Dim sig() As Byte = key.SignData(data, CryptoConfig.MapNameToOID("SHA256"))
This will throw following exception:
System.Security.Cryptography.CryptographicException: 'Invalid
algorithm specified.'
The root cause is that RSACryptoServiceProvider does not support SHA256. That's why I suggest replacing it with RSACng in the following way:
Dim rsa As RSA = certificate.GetRSAPrivateKey()
Dim data() As Byte = System.Text.Encoding.Unicode.GetBytes(signatureUrl)
Dim sig() As Byte = rsa.SignData(data, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1)
Method GetRSAPrivateKey was added to X509Certificate2 class only since .NET Framework 4.6, so consider upgrading if you get following error:
error BC30456: 'GetRSAPrivateKey' is not a member of
'X509Certificate2'
UPDATE 2 (regarding URL validation)
The page you referenced contains openssl command for verifying the signature:
openssl dgst -sha256 -signature signature.bin -verify public-key.pem url.txt
However in your case it will be just a sanity check, because you have just generated the signature with a valid procedure. So answering your question:
How can I check whether the URL I now end up with is valid?
The best check is just to send request to AMP Cache with signed URL and check the response. I haven't used AMP Cache before but I believe it will respond with some HTTP error if the signature is invalid.
UPDATE 3 (regarding failed signature verification)
Update AMP Content page contains following command line for signing the URL:
echo -n >url.txt
'/update-cache/c/s/example.com/article?amp_action=flush&_ts=1484941817'
cat url.txt | openssl dgst -sha256 -sign private-key.pem >signature.bin
I have compared result signature built by this command with the signature calculated by the code from my answer. It turned out that they differ. I have researched the possible root cause and found that the problem is caused by the way we get URL bytes. Currently it's:
Dim data() As Byte = System.Text.Encoding.Unicode.GetBytes(signatureUrl)
However we should sign the URL represented in ASCII. So replace above line with:
Dim data() As Byte = System.Text.Encoding.ASCII.GetBytes(signatureUrl)
Now both signatures, from openssl utility and the code above, matches. If after the fix you still get URL signature verification error from Google AMP, then the problem will be with the input URL passed for signing.
UPDATE 4 (Getting PFX from private and public keys)
Generate private key:
openssl genrsa 2048 > private-key.pem
Generate public key:
openssl rsa -in private-key.pem -pubout > public-key.pem
Create certificate signing request:
openssl req -new -key private-key.pem -out certificate.csr
Create certificate:
openssl x509 -req -days 365 -in certificate.csr -signkey private-key.pem -out public.crt
You will be asked here for some certificate fields, e.g. Country Name, Organization Name, etc. It does not really matter which values you use, since you need this certificate for test purposes.
Create pfx file:
openssl pkcs12 -export -out keys.pfx -inkey private-key.pem -in public.crt
This is the code I use for signing a string with a certificate from disk. I modified it for use in an url. Maybe it will be of help to you.
public string signString(string originalString)
{
//load the certificate from disk
X509Certificate2 cert = loadCertificateFromFile("myCert.pfx", "myPassword");
//get the associated CSP and private key
using (RSACryptoServiceProvider csp = (RSACryptoServiceProvider)cert.PrivateKey)
using (SHA1Managed sha1 = new SHA1Managed())
{
//hash the data
UnicodeEncoding encoding = new UnicodeEncoding();
byte[] data = encoding.GetBytes(originalString);
byte[] hash = sha1.ComputeHash(data);
//sign the hash
byte[] signed = csp.SignHash(hash, CryptoConfig.MapNameToOID("SHA1"));
//convert to base64 and encode for use in an URL
return Server.UrlEncode(Convert.ToBase64String(signed));
//or return a regular string
//return Encoding.Default.GetString(signed);
}
}
public bool verifyString(string originalString, string signedString)
{
//convert back from base64 and url encoded string
byte[] signature = Convert.FromBase64String(Server.UrlDecode(signedString));
//or a regular string
//byte[] signature = Encoding.Default.GetBytes(signedString);
//load the certificate from disk
X509Certificate2 cert = loadCertificateFromFile("myCert.pfx", "myPassword");
//get the associated CSP and private key
using (RSACryptoServiceProvider csp = (RSACryptoServiceProvider)cert.PrivateKey)
using (SHA1Managed sha1 = new SHA1Managed())
{
//hash the data
UnicodeEncoding encoding = new UnicodeEncoding();
byte[] data = encoding.GetBytes(originalString);
byte[] hash = sha1.ComputeHash(data);
//sign the hash
byte[] signed = csp.SignHash(hash, CryptoConfig.MapNameToOID("SHA1"));
//verify the signature
return csp.VerifyHash(hash, CryptoConfig.MapNameToOID("SHA1"), signature);
}
}
public X509Certificate2 loadCertificateFromFile(string path, string password)
{
//get the absolute path
string absolutePath = Server.MapPath(path);
//for non-website users, use this
//string absolutePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, path);
if (!string.IsNullOrEmpty(password))
{
return new X509Certificate2(absolutePath, password, X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.Exportable);
}
else
{
return new X509Certificate2(absolutePath);
}
}
Usage:
string originalString = "This is a test string";
string signedString = signString(originalString);
bool stringIsCorrect = verifyString(originalString, signedString);
I now see you use VB. You can use this to convert the code http://www.carlosag.net/tools/codetranslator. However it may need some modification afterwards as I don't know the accuracy of the converter.
I am able to generate an AES key,and along with my OpenSSL generated public key I have imported,wrap it with code like:
window.crypto.subtle.wrapKey(
'raw',
sharedKey,
publicKey,
{
name: 'RSA-OAEP',
hash: {name: "SHA-1"}//I can change this to SHA-256 or any valid hash function
}
).then(function(encryptedSharedKey) {
resolve(encryptedSharedKey);
}).catch(function(err) {
reject(err);
});
My question is, regarding OpenSSL RSA OAEP keys, it seems like it always uses SHA-1 for padding. It seems like no matter what hash I specify in the webCrypto wrapKey function, I am still able to decrypt the encryptedSharedKey with my OpenSSL private key with a command like
openssl pkeyutl -decrypt -pkeyopt rsa_padding_mode:oaep -inkey myprivatekey -in sessionKey.enc
Is there a bug where webcrypto is not actually changing the hash type when I wrap the keys, or do I misunderstand how the hash plays a factor?
In the simple case outlined below, the user will successfully import but I receive an INVALID_PASSWORD when I try to authenticate.
The salt and passwordHash where pulled from an LDAP user directory (apacheds) using the {SSHA} auth schema. When I run the following JS I receive the passwordHash I'm expecting:
var sha1Hex = require('sha1-hex');
var saltHex = Buffer.from("ktuF+dzYMQU=", 'base64').toString('hex');
var passwordHex = Buffer.from("demo", 'utf-8').toString('hex');
var hash = sha1Hex(Buffer.from(passwordHex + saltHex, 'hex'));
var hashBase64 = Buffer.from(hash, 'hex').toString('base64');
console.log(hashBase64);
firebase CLM import command:
firebase auth:import users.json --hash-algo=SHA1 --rounds=80
users.json file:
{
"users": [
{
"localId": "3c872eee-e86c-4b44-9840-bcebaac18f2c",
"email": "test#example.com",
"salt": "ktuF+dzYMQU=",
"passwordHash": "BuapoGGKIdfGprfMFjj3N9I7Ljg=",
"displayName": "Demo User",
}
]
}
Credentials that should work with imported user:
Username: test#example.com
Password: demo
Firebase web api login command (returns INVALID_PASSWORD):
firebase.auth().signInWithEmailAndPassword('test#example.com', demo);
I'm not confident about the --rounds=80 parameter, seems weird that needs to be specified at all when using sha1. I've also tried with --rounds=0.
After trying this out with Java MessageDigest SHA-1 to verify the password hash, one of our uber auth experts said that it looks like you're doing passwordHash = SHA1(plainPassword + salt)
However, the Firebase Auth system uses passwordHash = SHA1(salt + plainPassword).
So I think if you switch that around, it should produce better results.
You can configure the order of the password and hash.
The hash-input-order accept two values: SALT_FIRST or PASSWORD_FIRST.
In your case you want to do:
firebase auth:import users.json --hash-algo=SHA1 --rounds=80 --hash-input-order=PASSWORD_FIRST
For anyone like me that went hours finding a solution for this issue, please refer to this.
Basically, passwordHash should be in Base64 encoding from un-hex-ed SHA1 hash. And --rounds=1 works fine.
I am trying to encrypt some text in JavaScript and then send it to PHP (etc: with Ajax) to decrypt it there and save it (etc: In MySQL).
Here is my code so far:
In JavaScript:
I am using this library for the encryption:
http://travistidwell.com/blog/2013/02/15/a-better-library-for-javascript-asymmetrical-rsa-encryption/
function ConvertToURL(data) {
// Converts data to URL friendly form
// etc: Replaces '+', '/', '=' with 'plus', 'slash', 'equal'
};
function AjaxOrder(data) {
// Sends data in PHP with Ajax
}
var publicKey = '-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDlOJu6TyygqxfWT7eLtGDwajtN
FOb9I5XRb6khyfD1Yt3YiCgQWMNW649887VGJiGr/L5i2osbl8C9+WJTeucF+S76
xFxdU6jE0NQ+Z+zEdhUTooNRaY5nZiu5PgDB0ED/ZKBUSLKL7eibMxZtMlUDHjm4
gwQco1KRMDSmXSMkDwIDAQAB
-----END PUBLIC KEY-----';
var encrypt = new JSEncrypt();
encrypt.setPublicKey(publicKey);
var encrypted = encrypt.encrypt('Text to send.');
*// And now I am sending the encrypted text with some Ajax function*
AjaxOrder(ConvertToURL(encrypted));
In PHP:
$dataPost = $_POST('dt');
function ConvertFromURL($data) {
// Converts $data to original form
// etc: Replaces 'plus', 'slash', 'equal' with '+', '/', '='
}
function ReturnData($data) {
// Sends $data back in JavaScript as an answer to Ajax
}
$privateKey = '-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----';
openssl_private_decrypt(ConvertFromURL($dataPost), $decryptedWord, $privateKey);
ReturnData(base64_encode($decryptedWord));
Now the answer from PHP is empty every time. Any ideas to make this work?
Thank you for your time!
Use HTTPS.
What you are doing will never be able to protect you against active attacks (MitM) since you don't have any trust anchors, and it is very likely that you will make some stupid mistake that will make it insecure.
Either way, you cannot encrypt more than a few hundred bytes directly with RSA. Thus, you will have to securely generate a random symmetric key (doing that properly in JavaScript is not easy), encrypt the data with it using a secure symmetric cipher (e.g. AES) in a secure block cipher mode, then encrypt the symmetric key with RSA. Learning how to do it "properly" will take you much more time than really doing it properly, and that is, configuring SSL.