r - Soap API request with httr

Question

I'm trying to send a SOAP request to receive some data with R and httr, but receive something i cannot interpret and fix.

I have a web certificate in a .p12 file, and a password for it (in text).

I tried 2 approaches:

library(httr)

url <- 'https://www.b2b.preops.nm.eurocontrol.int/B2B_PREOPS/gateway/spec/26.0.0'

payload <- '<item:itemName>
         <userId>myUserID</endUserId>
         <sendTime>2023-03-28 11:42:28</sendTime>
        <data>
            <type>NEW</type>
        </data>
      </item:itemName>'

keystore <- "my_p12_file.p12"
keystore_password <- "the_password"

headers <- list(`Content-type`="application/soap+xml;charset=UTF-8", SOAPAction = "Get")

response <- POST(url, 
                 body = payload,
                 add_headers(headers),
                 config = list(
                   sslcert = keystore,
                   sslkey = keystore_password
                 ),
                 verbose(
                   data_out = F, 
                   data_in = F, 
                   info = T, 
                   ssl = F)
)

Here i received this note:

*  Uses proxy env variable https_proxy == 'http://my_proxy_details:port'
*  Hostname in DNS cache was stale, zapped
*    Trying HIDDEN...
*  Connected to HIDDEN (#5)
*  allocate connect buffer
*  Establish HTTP proxy tunnel to HIDDEN_LINK
-> CONNECT HIDDEN_LINK HTTP/1.1
-> Host: HIDDEN
-> User-Agent: libcurl/7.84.0 r-curl/5.0.0 httr/1.4.5
-> Proxy-Connection: Keep-Alive
-> 
<- HTTP/1.1 200 Connection established
<- 
*  Proxy replied 200 to CONNECT request
*  CONNECT phase completed
-> POST /LINK_HTTP
-> Host: HIDDEN_HOST
-> User-Agent: libcurl/7.84.0 r-curl/5.0.0 httr/1.4.5
-> Accept-Encoding: deflate, gzip
-> Accept: application/json, text/xml, application/xml, */*
-> Content-Length: 897
-> 
*  Mark bundle as not supporting multiuse
<- HTTP/1.1 200 OK
<- connection: close
<- content-length: 36
<- content-type: application/json
<- date: Wed, 29 Mar 2023 19:17:37 GMT
<- p3p: CP="NON CUR OTPi OUR NOR UNI"
<- expect-ct: max-age=86400,enforce
<- permissions-policy: accelerometer=(), camera=(), geolocation=(), gyroscope=(), magnetometer=(), microphone=(), midi=(), payment=()
<- x-frame-options: SAMEORIGIN
<- x-content-type-options: nosniff
<- cache-control: no-store
<- x-xss-protection: 1
<- content-security-policy: default-src 'none'; base-uri 'self'; upgrade-insecure-requests; block-all-mixed-content; frame-ancestors 'self'; form-action 'self'
<- referrer-policy: strict-origin-when-cross-origin
<- strict-transport-security: max-age=63072000; includeSubDomains; preload
<- feature-policy: accelerometer 'none'; camera 'none'; geolocation 'none'; gyroscope 'none'; magnetometer 'none'; microphone 'none'; midi 'none'; payment 'none'
<- pragma: no-cache
<- 
*  Closing connection 5
*  schannel: shutting down SSL/TLS connection with HIDDEN PORT HIDDEN

Then I typed in:

response

and I received

Response https_link_hidden
  Date: 2023-03-29 19:17
  Status: 200
  Content-Type: application/json
  Size: 36 B
{
    "operation" : "failed_cert"
}

as proposed I tried to read the p12 file using this solution

library(openssl)
ps_key <- openssl::read_p12(keystore, keystore_password)

and then run the modified code:

response <- POST(url, 
                 body = payload,
                 #add_headers(headers),
                 config = list(
                   sslcert = ps_key$cert,
                   sslkey = ps_key$key
                 ),
                 verbose(
                   data_out = F, 
                   data_in = F, 
                   info = T, 
                   ssl = F)
)

I get this strange binary error H��Jq7�0

any help/opinion is appreciated