Signing API requests

General requirements for requests:

  • Must use HTTPS.
  • Must contain the apikey parameter. To learn more, see API Key.
  • Must be signed, with the signature added to the X-YaCourier-Signature header.
  • The user_agent used to form the signature must be passed in the headers.

Signature calculation algorithm

The signature is calculated using a 16-character secret (obtained from the client manager or support) and the SHA-256 algorithm. Once calculated, the signature is converted to HEX format.

Warning

The secret is not a signature but it's used for its calculation.

Forming a signature involves:

  • User agent
  • POST and GET request methods
  • Request-URI (starts with /, no host specified)
  • Message body

General description of the algorithm:

items_to_sign = { user_agent, method, " ", uri, body }
signature = HMAC(<secret>)

for item in items_to_sign:
    signature = HMAC(signature, item)

headers['X-YaCourier-Signature'] = hex_encode(signature)

Sample (based on the randomly generated cb6628c7407fd3c570bebbd7c36731f1 secret):

import hashlib
import hmac

KEY = "cb6628c7407fd3c570bebbd7c36731f1"
USER_AGENT = "TestUserAgent"
URI = "/test/uri"
BODY = "TestBody"

def gen_signature(key, parts):
    HMAC = hmac.new(key.decode('hex'), None, digestmod=hashlib.sha256)
    for part in parts:
        HMAC.update(part)
    return HMAC.hexdigest()

print gen_signature(KEY, [USER_AGENT, "POST", " ", URI, BODY])
import hashlib
import hmac

KEY = "cb6628c7407fd3c570bebbd7c36731f1"
USER_AGENT = "TestUserAgent"
URI = "/test/uri"
BODY = "TestBody"

def gen_signature(key, parts):
    HMAC = hmac.new(bytes.fromhex(key), None, digestmod=hashlib.sha256)
    for part in parts:
        HMAC.update(part.encode('utf-8'))
    return HMAC.hexdigest()

print(gen_signature(KEY, [USER_AGENT, "POST", " ", URI, BODY]))
$KEY = 'cb6628c7407fd3c570bebbd7c36731f1';
$USER_AGENT = 'TestUserAgent';
$URI = '/test/uri';
$BODY = 'TestBody';

function genSignature($secret, array $parts): string {
    $ctx = hash_init('sha256', HASH_HMAC, hex2bin($secret));
    foreach ($parts as $part) {
	   hash_update($ctx, $part);
    }
    return hash_final($ctx);
}

echo genSignature($KEY, array($USER_AGENT, 'POST', ' ', $URI, $BODY));

Result:

47abf7284eab22da90f591ff981bc0c4630a8e3a38c9e1cf8d881eb952c22333

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