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API Authentication

Learn how to implement API Authentication so you can start making calls

All API calls will require authentication. HMAC is a more secure solution, but it can be faster to get started on basic authentication, however, for production use, we "require" HMAC authentication be used. This is the same as Decryptx.

HMAC Authentication

The hash-based message authentication code (HMAC) method provides replay protection, time-to-live, and request integrity. Our implementation requires that you use the sha-256 and hmac-sha-256 hashing algorithms. Before you can implement this auth method, you must ensure that you have a shared key. If you were not given a shared key when you registered, please request one from Bluefin Support.

An HMAC authentication header must contain the following properties:

PropertyDescription
usernameThis property must be set to your partnerId.
nonceThis property must be set to a nonce. A nonce is a unique random string. If a nonce is encountered more than once during a 15 minute period the API call is rejected. It is your responsibility to ensure that the nonce is unique.
timestampA unix timestamp. Our service will reject API calls with a timestamp older than 15 minutes.
responseThe response property is a HMAC-SHA256 hash (in hexadecimal format) of a number of the API call's properties. See the guide Building the String-to-Hash for a detailed description of string that must be included in the hash. Once you have the StringToSign, generate the response like this: Hex( HMAC-SHA256( sharedKey, StringToHash ) );

Building an HMAC Authentication Header

  1. Generate a nonce
1l5daa1ju1b7lmljc5p4nev0ve
  1. Generate a unix timestamp
Math.round(new Date().getTime()/1000)
//output 1489574949
(int) (System.currentTimeMillis() / 1000L)
//output 1489574949
  1. Generate the content hash by SHA-256 hashing the request body.
\n represents a newline character and \t represents a tab character.

sha-256({ \n\t\"partnerId\":                     \"WATERFORD\",\n  \t\"partnerKey\": \"ef1ad938150fb15a1384b883a104ce70\",\n  \t\"devicePayload\": \"02C400C037001C0A8692;6011********3331=2212:***?*15=090210=2CB56EC5E025C2F3C2C67FCF2D0C4C39BB19E60EF31192675E5F1DB6A90070E3000000000000000000000000000000000000000035343154313132373038629949960E001D20004A029603\",\n  \t\"clientId\": \"my_client\",\n  \t\"reference\": \"723f57e1-e9c8-48cb-81d9-547ad2b76435s\"\n})

//output 9db4a2e377abca97c72c5d8b449948d3fb22fa18f305c3730f227e4f6514d4ce
  1. Build the String-to-Hash.

When creating the String-to-Hash, it is important that you follow the format described exactly as outlined below, otherwise the request will be rejected. The String-to-Hash is composed of the following elements.

ElementDescription
HttpVerbShould be set to 'POST' for all API calls.
CanonicalizedResourceShould be the HTTP Request URI, without protocol, port and domain parts; the following list outlines the appropriate value for each endpoint:

validate partner = /api/partner/validate

process payload = /api/decrypt/parser
nonceSame value as set in the auth header nonce property.
timestampSame value as set in the auth header timestamp property.
ContentHashA SHA-256 hash in hexadecimal format of the HTTP POST's body. Our service expects you to hash the whole body, including any leading and trailing whitespaces that you may have included. See step 3.
\nThe Unicode code point U+000A, commonly called newline).

The String-to-Hash is composed of these elements gathered together in this exact format. Once you have the String-to-Hash, you pass it into the HMAC-SHA256 hashing algorithm to generate the HMAC authentication header's response property.

HttpVerb + " " + CanonicalizedResource + "\n" + nonce + "\n" + timestamp
  + "\n" + "\n" + ContentHash;

For our example the String-to-Hash is:

"POST /api/authdebug\n1l5daa1ju1b7lmljc5p4nev0ve\n1489574949\n\n9db4a2e377abca97c72c5d8b449948d3fb22fa18f305c3730f227e4f6514d4ce"
  1. HMAC-SHA256 hash the String-to-Hash with the secret key:
Hex( HMAC-SHA256( 'ef1ad938150fb15a1384b883a104ce70',
                 "POST /api/authdebug\n1l5daa1ju1b7lmljc5p4nev0ve\n1489574949\n\n9db4a2e377abca97c72c5d8b449948d3fb22fa18f305c3730f227e4f6514d4ce" ) )

//output 7fd904ec88c5dc9217e178bc8e115b950c243197b5116e3e1fc43061eeb846ac
  1. Build the Digest authentication header:
Authorization: Hmac username="WATERFORD", nonce="1l5daa1ju1b7lmljc5p4nev0ve",  timestamp=1489574949, response="7fd904ec88c5dc9217e178bc8e115b950c243197b5116e3e1fc43061eeb846ac"

Example:
The following example is for demonstration purposes only. The WATERFORD user is not configured for HMAC authentication and the header's timestamp is out of date; if you try the cURL command, you will receive an authentication required error message.

curl 'https://secure-cert.decryptx.com/api/partner/validate' \
    -X POST \
    --header 'Content-Type: application/json' \
    --header 'Accept: application/json' \
    --header 'authorization: Hmac username="WATERFORD", nonce="1l5daa1ju1b7lmljc5p4nev0ve",  timestamp=1489574949, response="7fd904ec88c5dc9217e178bc8e115b950c243197b5116e3e1fc43061eeb846ac"' \
    -d '{
            "reference"  : "723f57e1-e9c8-48cb-81d9-547ad2b76435"
        }'

RSA Authentication

Generate RSA Key Pair

The following section outlines the steps involved in generating an RSA key pair with OpenSSL. We recommend that you generate a 2048 bit key pair as 1024 bit keys are no longer considered secure and 4096 bit keys consume considerable CPU resources when signing API calls.

  1. Generate a 2048-bit RSA private key and write it to a file private.pem.
#Output an RSA private key with 2048 bit protection.
openssl genrsa -out private.pem 2048
  1. Generate a PKCS8 formatted file from the private key and write it to file private8.pem. The private8.pem file must be used in the RSA-DIGEST function to sign the requests.
#Generate a pk8 file from the private key.
openssl pkcs8 -topk8 -inform PEM -outform PEM -nocrypt -in private.pem -out private8.pem
  1. Generate the public key file from the private key and write it to a file public.pem.
#Generate a public key from the private key.
openssl rsa -in private.pem -outform PEM -pubout -out public.pem

Authentication Header Guide

The RSA authentication method is almost identical to HMAC. The only difference is that it uses an RSA private key to sign the String-to-Hash and a RSA public key to validate that the signature is valid. RSA keys provide a more secure way of signing your auth headers than using a password. While a password can eventually be cracked with a brute force attack, RSA keys are nearly impossible to decipher by brute force alone. The downside of using RSA to sign API calls, is that RSA signatures require a lot more CPU resources (up to ~250 times) than HMAC hashing.

Our Generating an RSA key pair guide outlines how you can create a public and a private key. You must send the public key to Bluefin, and keep the private key on your server.

PropertyDesecription
username This property must be set to your partnerID.
nonce This property must be set to a nonce. A nonce can be any arbitrary string, however each nonce can once over a 15 minute period. Our service keeps a record of these nonces; if a nonce is encountered more than once during a 15 minute period the API call is rejected and an auth error response is produced. It is up to you to keep the nonce unique.
timestamp A unix timestamp. Our service will reject API calls with a timestamp older than 15 minutes.
response The response property is an RSA private key signature of a number of the API call's properties.

Next Steps

Once you're set up to add authentication to your headers, iFrame users will probably want to move along to Detokenization. For those of you that plan to tokenize with the API move along to Tokenization

Updated about a month ago


API Authentication


Learn how to implement API Authentication so you can start making calls

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